Categories of Indoor Air Pollutants

Smarter Homes: Ventilation

With good ventilation, your home will be drier, healthier and more comfortable.

Ventilation is about helping air to circulate in your home. It allows moisture and airborne pollutants to escape, and fresh, clean air to be drawn into your home. Well-designed ventilation will provide cooling in summer. In winter, it will let stale air out but keep warmth in.

Effective ventilation depends to a significant extent on the size, placement and type of windows, doors and other openings in your home. With good design, you can control the circulation of air, rather than having draughts.

With good design, you can use windows, vents and other openings for most ventilation – this will save on your energy costs.  However, you may need some mechanical (active) ventilation, for example, extractor fans to expel moist air from the kitchen, bathroom and laundry outside.

Does ventilation matter?

Yes. A 2005 BRANZ survey of the condition of New Zealand homes found that many were damp and poorly ventilated.

Most bathrooms relied only on windows for ventilation. Only half of kitchens vented moist air to the outside. And 40% of timber-framed homes had poor or seriously inadequate subfloor ventilation.

Poor ventilation allows moisture and airborne pollutants to build up inside your home. This can cause health problems such as asthma for you and other members of your household. Moisture can also make your home uncomfortable to live in and damage its structure.

When should you think about ventilation?

Planning a home or renovation

If you're building or renovating, ventilation should be considered early in the design process.

Good design should strike a balance between the need to introduce fresh, healthy air into your home and the need to maintain comfortable temperatures, so ventilation should be considered alongside passive heating and passive cooling options. If you consider heating without ventilation, you may end up with a home that's warm but not as healthy or comfortable to live in as it could be.

During and after construction

During the construction process and for a few weeks afterwards, you'll need to provide good ventilation to minimise your exposure to airborne pollutants such as formaldehyde from new building materials. See Unhealthy air for more.

In your existing home

Ventilation can be improved in an existing home without making significant alterations. Moving a door or window, or removing an internal wall might make a significant difference.

For ventilation to work as effectively as it should, your home should be well insulated. Then you can control your ventilation, rather than being draughty and cold.

Older homes tend to be less airtight than more modern homes. This can allow for some natural ventilation - but can also mean they're draughty and harder to heat. As a general rule of thumb, houses built before the 1960s will be very draughty, and houses built between the 1960s and 1980s will be quite draughty.  Modern construction, however, is much more airtight, meaning that problems with inadequate ventilation become more frequent.

Passive ventilation

How does it work?

Passive ventilation uses doors, windows, vents, louvres and other openings to bring fresh air into your home and let stale air out. The size and placement of these openings can be used to guide air into and through your home.

Where cooling is required, windows or other openings on upper levels can be opened to let warm air escape. In winter, well-designed passive ventilation refreshes the air in your home without creating draughts or letting out too much heat.

Passive ventilation can only work if air has clear, uninterrupted pathways through your home. You can maximise air flow by designing open plan areas or having high vents or other openings between rooms. In general, windows should be larger on one side of the home than the other in order to encourage air flow.

If your home is designed for passive ventilation, all you'll need to do is open and close windows, doors or other vents as needed to reduce the temperature and improve the quality of the air you're breathing.

To encourage cool air flow, you'll need larger windows opening to the breeze and smaller, higher windows on the walls on the opposite side of the house

Options

The appropriate ventilation options for your home will depend on the climate and microclimate of the area you live in, and what prevailing breezes there are. As a rule of thumb, the area of windows, doors and other vents that can be opened up to the outside should be at least 5% of the floor area for each living space - and more for high-use areas.

Some points to consider:

• Windows or other openings on opposite sides of your home will help draw air through.
• Opening windows on the south and east side are best for allowing cool breeze into your home from early in the day. Openings on the north and west sides, higher up, will keep the air moving.
• Vents or other openings in the roof or on upper floors will allow air to escape as heat rises.
• Built-in vents, louvres, slots and gaps in door or window framing can provide low-level ventilation over long periods without creating draughts or security risks.
• Different types of window can be used to guide air into your home - for example, side opening windows are better at catching breezes and pulling them into the house, than awning opening windows
• If your home is on more than one level, make sure there are opening windows and doors on each level. As hot air rises, high windows which can be left open on upper floors can be a good way of ventilating your house during summer.
• Fly screens and security stays installed on windows mean they can be left open at night, or when you’re out during the day, to help the house keep cool in summer
• Don’t forget to ensure cross-ventilation under your floor to get rid of dampness (see Moisture for more information)

See Glazing for more about window design.

Background air leakage

Some features will provide low-level background movement of air between your home's interior and exterior. This is often called air infiltration, and can cause draughts and heat loss in winter. For example:

• timber joinery around windows and doors
• flues and chimneys
• recessed ceiling and light fittings
• extractor fan grills.

It is better to plan good ventilation together with a well-insulated house, than rely on leaks and draughts which you cannot control when you need to and won’t necessarily ventilate the right places.

Active ventilation

Active ventilation is ventilation provided mechanically - for example, by extractor fans, range hoods and whole house ventilation systems. These systems run on electricity - the bigger the system and the more components, the more power it will use.

A well-insulated, well-designed home may only need to use active ventilation for rooms where moisture is generated (bathroom, laundry and kitchen), while passive ventilation will be sufficient for maintaining air quality through the rest of your home.

Active ventilation may also be needed to get warm air into cooler, damper areas such as south-facing rooms - for example by heat transfer systems (see Tips for efficient home heating for more information).

Extractor fans/range hoods

Extractor fans quickly remove moist air from bathrooms, toilets and laundries. Range hoods do the same job for kitchens.

It's important to choose the right-sized fan for the job. A fan that's too small won't remove enough moist air to keep your home dry. A fan that's too large can create draughts. For a typical bathroom or toilet a ventilation rate of 25 litres per second should suffice. For more information see Table B1 in AS 166 part 2.

Extractor fans should be placed as close to the moisture source as possible. They must be vented to the outside or the moist air will end up in your roof space, damaging your insulation and roof supports (see Moisture for more).

Because extractor fans remove moist air but don't bring in fresh air to replace it, you'll need some other way of getting fresh air into the room. By placing air vents on the opposite side of the room from the extractor fan, or slightly opening doors or windows, you can encourage air flow.

Solar or electric-powered roof ventilation

These simple fan, duct and vent systems take hot air from the top of your home or roof space out through the roof.  Solar-powered systems are available that cost nothing to run.

Whole house ventilation systems

Whole house ventilation systems can be useful to bring in fresh air and combat condensation in modern airtight houses. There are two main types of whole house ventilation systems:

• Positive pressure / Roof cavity ventilation systems
• Balanced pressure / Heat recovery ventilation systems.

Positive pressure / Roof cavity ventilation systems

Positive pressure or roof cavity ventilation systems are the most common type available in New Zealand. They bring filtered air from the roof space into the house through a single, or multiple, ceiling vents. This forces the stale air to leak out through gaps, windows and doors. The performance of these systems depends on the sizing of the fans, the distribution of the ceiling vents throughout the house and how airtight your home is.

In an airtight house, pushing the filtered air into the house creates a positive pressure inside the house which causes inside air to move out.  However, in draughty houses, there are too many gaps and leakage points - the ventilation system will not be able to force the air into each room of the house.

The ventilation system will also not work properly if the roof space is not properly sealed from the inside of the house (for example, if you have downlights).  The stale indoor air will leak back into the roof and be pumped back into the house again.
Ventilation systems should bring fresh air into the house, but your roof space may be polluted by dust, mould and vermin. Most systems are fitted with filters - the quality of the air entering the house depends on the filter type and whether you regularly change or clean filters.

The Energy Efficiency and Conservation Authority (EECA) recommends that the home ventilation systems source their ‘fresh’ air from the outside, not from the roof space.

Balanced pressure / Heat recovery systems

Balanced pressure / Heat recovery ventilation systems are particularly suitable for homes in colder areas of the country, if they are already well heated and if they are reasonably airtight.

These systems have two fans: an intake fan which supplies fresh outdoor air into the house through several ceiling vents; and an exhaust fan which takes stale air from inside the house and discharges it to the outside. An air-to-air heat exchanger (usually in the roof space) transfers heat from the inside air to the incoming fresh air from outside. In this way, most of the heat is recovered.

Some products include additional features to utilise heat in the roof space when it is available on sunny winter days, or to avoid warming incoming fresh air in summer when it is hot.

To ventilate effectively, these systems need gaps or vents in internal doors so that air can flow through all areas of the house between the intake and exhaust.

In winter, the heat exchanger transfers a portion of the heat in the warm exhaust air to the colder outdoor air, thus reducing the heat loss associated with the ventilation. To be effective, the house should be airtight so that almost all ventilation air passes through the heat exchanger, rather than being leaked out through draughts.
Heat recovery systems provide good fresh air ventilation but they are not a heating system.  However, they can recover between 67–95% of the heat from the inside air which means that the fresh air coming in will be warmer. This means you will need less heating to warm your home.

http://www.smarterhomes.org.nz/design/ventilation/

Energy Source Builder: Home Ventilation Options For Home Builders

In the old days, buildings were ventilated by the wind and other uncontrolled forms of air leakage. However, most people no longer accept the cold, drafty houses of the old days. Now, houses are expected to be cozy, draft free and energy efficient. A tight home is fine, as long as it comes with a controlled ventilation system. Modern building materials tend to make newly constructed homes much tighter than old ones. Plywood, housewrap, better windows, caulk and expanding foam are a few examples of common products that tighten a house. Research has shown that some builders inadvertently build houses much tighter than intended.

In any home, uncontrolled air leakage is a fickle ventilator. The only way to ensure adequate ventilation is to install some type of automatically controlled ventilation system. As you'll see, you have quite a few choices.

Ventilation Standards

Exhaust fans in the kitchen and bathrooms are standard equipment in new homes. They provide spot ventilation to expel moisture and odors from limited areas. With spot ventilation, people sense an obvious problem and then manually flip a switch to solve the problem.

The controlled ventilation described in this article is intended to maintain overall indoor air quality. It differs from spot ventilation in three ways. It affects the entire living space. It provides makeup air from outside. And, it's controlled automatically. It's called controlled ventilation to distinguish it from the more limited spot ventilation.

According to standards published by the American Society of Heating, Refrigeration and Air-conditioning Engineers (ASHRAE), houses should have a controlled ventilation rate of 15 cubic feet per minute (cfm) per person. So, a household of four would require 60 cfm. Some building codes and utility programs also use 0.35 air changes per hour (ach) as a ventilation target. (To quickly estimate the air flow in cfm needed to meet the 0.35 ach requirement, divide the floor area in square feet by 20.) Remember these ventilation targets are for controlled ventilation, not spot ventilation.

Basic Functions

Ventilation systems are more than exhaust fans. They serve three important functions:

• Expel stale air containing water vapor, carbon dioxide, airborne chemicals and other pollutants.
• Draw in outside air, which presumably contains fewer pollutants and less water vapor.
• Distribute the outside air throughout the house.
• Control system operation automatically.

The basic ventilation system has two elements. First, there's a fan to pull stale air out. Pickup points for stale air are generally in high moisture areas, such as the kitchen, utility and bathrooms. Second is the makeup air supply. Outside air is delivered around the house, with one supply point in each bedroom and at least one in the living area. The suction, also called negative pressure, created by the exhaust fan pulls air through the house from supply points to the pickup points. By properly locating the pickup and supply points, you make outside air travel through the entire house.

Equipment Options

The equipment that performs these four basic functions comes in all shapes, size and costs. Here are six sample systems:

• Surface-mounted Fan
• Remote-mounted In-line Fan
• Remote-mounted Multiport Fan
• Balanced Ventilator
• Air-to-Air Heat Exchanger
• Exhaust Air Heat Pump

Exhaust Only vs. Balanced

In simpler systems, the main component is an exhaust fan that places the building under a slight negative pressure. This draws outside air into the house through passive fresh air inlets. Because they are simpler, negative pressure systems are generally less expensive. Plus they help prevent water vapor from migrating into building cavities, such as walls and attics, where the vapor could condense and cause problems.

Unfortunately, fireplaces, wood stoves and gas-burning appliances were not designed to operate in a negative pressure environment. Under some conditions, even a slight negative pressure could cause flue gases, including carbon monoxide, to spill into the living space. You can either leave them out or install only sealed combustion appliances that draw air from outside.

Other systems strive for a balanced flow by using two fans: one for exhaust and another for fresh air. In theory, backdrafting shouldn't be an issue. However, experience with forced-air heating systems shows that balanced air flow can be difficult to achieve. Detailed duct design and careful installation are needed. Once installed the system must be adjusted. Even then the carefully balanced air flow can be thrown off by someone closing a door between a supply and a pickup.

Heat Recovery or Not

Controlled ventilation systems collect the outgoing air into a single duct so it's possible to capture heat from that air with a heat-recovery ventilator (HRV). The most common type of HRV is an air-to-air heat exchanger. It transfers heat from the outgoing air stream to the incoming one. In these systems, air flow is balanced. Another type of HRV is an exhaust air heat pump. Commonly used in Sweden, it transfers heat from the outgoing air into the domestic water tank. The compressor is about the size of a window air conditioner.

High Quality Fans

Controlled ventilation systems operate many hours every day. Some never turn off. You want a durable, high-quality fan intended for continuous operation. Most high-quality fans use permanent split capacitor motors. Because this fan will run thousands of hours per year, look for a fan motor with low electrical consumption.

Noise prevents many people from operating fans. Surface-mounted fans should have a noise rating of 2.0 sones or less. A few manufacturers make fans with noise ratings less than 1.0 sone. Low sone ratings are less important for remote-mounted fans. However, you should use sound absorbing fan mounting and duct connections to prevent sound transmission into living areas.

Control Options

Here are a few control options that would work with most types of ventilation systems:

• Twenty-four hour timers allow the occupants to set certain times for ventilation. Set the timer to run the fan at least eight hours per day.
• Twist timers, also called interval timers, allow occupants to engage the fan whenever it's needed. Twist timers can be set up to 60 minutes and are generally located in bathrooms, utility rooms or kitchens.
• Speed controllers allow the fan to operate at low speed for background ventilation with a manual high-speed boost.
• Indoor air quality sensors activate a fan when they detect carbon monoxide, formaldehyde or other pollutants. This is an option in a couple of the more sophisticated controls.
• Dehumidistats engage the fan on rising humidity. They work well when relative humidity accurately indicates the need for ventilation. By setting the dial at 40, you are telling the dehumidistat to operate the fan whenever the humidity is 40 percent or higher. Unfortunately, relative humidity isn't always a reliable indicator. Climates with low humidity might never reach 40 percent, so the fan would never turn on. In wet climates the fan might never turn off. Dehumidistats aren't used as much as they once were because of this problem.
• Continuous operation simplifies the controls, but you should at least install an on/off switch. It's a good idea to locate the switch out of the way to reduce the chance that someone will accidentally flip it off.

People generally aren't reliable ventilation controllers, so you shouldn't count on a manual switch as the primary ventilation control. An automatic control is essential. However, people should have the option to activate ventilation when it's needed. So, most systems require at least two controls wired together. For example, a single 24-hour timer can control background ventilation while twist timers allow manual control.

Furnace Integration

It's tempting to combine a controlled ventilation system with existing forced-air heating and cooling ductwork. However, running the furnace blower causes three problems.

First, virtually all duct systems in new and existing homes have significant air leakage. Second, homes with forced air systems frequently have air pressure differences around the house that increase building air leakage. Third, typical furnace blowers are turned by large, inefficient motors. Running the typical single-speed blower an additional eight hours per day could easily burn more than 2,000 kWh per year. Some new air handlers reduce energy use with multispeed controls or more efficient motors.

Before using heating and cooling ducts for fresh-air distribution, these issues need to be resolved.

Occupant Information

Controlled ventilation systems are new to most home buyers. It's your job to educate the occupants.

• Label all components, including the fan, controls and ducts.
• Write a brief description of the system that explains the principles of operation, control strategy and maintenance. Attach product literature for the components used.
• Show the occupants the location of each component and how to operate the system.

Good information is essential because even the best ventilation system needs to be operated and maintained properly.

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Surface-mounted Fan

The simplest controlled ventilation system uses a quiet, high-quality surface-mounted fan. Fresh air enters through passive vents located in window sashes or outside walls. Surface-mounted fans provide good ventilation for smaller areas. Large houses may need more than one.

• Noise Rating: 2.0 sones or less
• Locations: central hallway or bathroom
• Air Flow Capacity: 80-400 cfm
• Heat Recovery: none
• House Pressure: negative
• Makeup Air: passive inlets
• Multispeed Operation: no
• Equipment Cost: $100 - 150
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Remote-mounted In-line Fan

Remote-mounted fans can pick up stale air from a single point. Or, they can be attached to a branched duct system with picks ups in two or three locations. This makes them a good choice for large houses. If properly rated, the fan could be attached to a range hood.

• Noise Rating: not applicable
• Locations: basement, attic or crawlspace
• Air Flow Capacity: 80-400 cfm
• Heat Recovery: none
• House Pressure: negative
• Makeup Air: passive inlets
• Multispeed Operation: optional
• Equipment Cost: $150 - 250
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Remote-mounted Multiport Fan

Large houses and several multifamily units can be ventilated by a single multiport fan. Some units can accept a duct from the range hood. Most operate at two or more speeds. Several manufacturers sell complete kits with all the ducts and accessories. These may cost a bit more, but the kits simplify installation.

• Noise Rating: not applicable
• Locations: basement, attic or crawlspace
• Air Flow Capacity: 100-400 cfm
• Heat Recovery: none
• House Pressure: negative
• Makeup Air: passive inlets
• Multispeed Operation: optional
• Equipment Cost: $200 - 700
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Balanced Ventilator

If you want balanced operation, without the extra expense of heat recovery, these would be a good choice. Only one or two manufacturers make balanced ventilators without heat recovery.

• Noise Rating: not applicable
• Locations: basement, attic or crawlspace
• Air Flow Capacity: 100-400 cfm
• Heat Recovery: none
• House Pressure: balanced
• Makeup Air: ducted
• Multispeed Operation: optional
• Equipment Cost: $400 - 800
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Air-to-Air Heat Exchanger

This type of heat-recovery ventilator provides balanced air flow and recovers up to 85 percent of the heat from outgoing air. By warming the incoming air, AAHXs provide greater comfort in cold climates than other types of ventilation systems. Units can be sized for any home and small commercial buildings.

• Noise Rating: not applicable
• Locations: basement, inside utility or any tempered space
• Air Flow Capacity: 150-1200 cfm
• Heat Recovery: 60 - 85% recovery efficiency
• House Pressure: balanced
• Makeup Air: ducted
• Multispeed Operation: standard on many units
• Equipment Cost: $800 - 2,000
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Exhaust Air Heat Pump

By employing a heat pump unit about the size of a window air conditioner, an exhaust air heat pump (EAHP) offers exceptional heat recovery efficiency. It can also provide most of the hot water needed by an average family. While the exhaust fan is controlled by timers, heat recovery engages only when hot water is needed. That means ventilation sometimes occurs without heat recovery. The operating characteristics of an EAHP lead to greater air flow than required for a typical small house.

• Noise Level: similar to refrigerator
• Locations: basement, inside utility or any tempered space
• Air Flow Capacity: 100-200 cfm
• Heat Recovery: 200 - 300% efficiency
• House Pressure: negative
• Makeup Air: passive inlets
• Multispeed Operation: no
• Equipment Cost: $1,000 - 3,000 

http://oikos.com/esb/39/VentOpt.html

Home ventilation systems

Home ventilation systems use fans to move air into your house and can provide continuous ventilation regardless of the weather and without the need to open doors and windows. Ventilation systems are not, however, an effective way to heat your home, or fix moisture or dampness problems.

Is a home ventilation system right for you?

A well designed and installed home ventilation system can offer you the convenience of good ventilation by delivering required air replacement continuously and independently of weather conditions.
Ventilation systems are not the only way to ventilate. Opening your doors and windows regularly is a simple and effective way to ventilate most homes.
Note that a home ventilation system is not a good solution for fixing cold and dampness problems in homes. If you are trying to make your existing home warmer, your money will be better spent on insulation and installing an effective heating system. If dampness is your main concern, then address the source of the moisture problem first, before looking at ventilation systems. (see related pages below)
Be aware that the performance of ventilation systems can vary widely depending on a range of factors - the type of system and how well it is installed, your type of house and the climate.
Ask your supplier for independent test performance reports for the system they are proposing. You should also get a ‘no questions asked' guarantee of performance that includes removal of the system if it doesn't work and repair of all damage to your home - e.g. holes in ceilings should be fixed to prevent undue air leakage.

Types of home ventilation systems

There are two types of home ventilation systems commonly available in New Zealand:

• Positive pressure roof cavity ventilation systems
• Balanced pressure heat recovery ventilation systems

Positive pressure/roof cavity heat transfer ventilation systems

Positive pressure/roof cavity ventilation systems are the most common type available in New Zealand. They force filtered air from the roof space into the house through a single, or multiple, ceiling vents. This pushes air inside the house out through gaps around doors and windows and other leakage areas.
How well these systems are able to ventilate the whole house depends on:

• the performance of the fans
• distribution of the ceiling vents throughout the house and;
• the building air tightness.

In draughty houses the ventilation system will struggle to force the air into each room of the house. If the roof cavity is not properly sealed from the inside of the house (for example if you have older recessed downlights) the system can short-circuit, i.e. indoor air will migrate into the roof cavity and be pumped back into the house again.
Roof spaces are often polluted with dust, mould and vermin. To keep the air supply clean, positive pressure/roof cavity ventilation systems are usually fitted with filters. The quality of the air entering the house is highly dependent on the filter type and how often it is cleaned. As suppliers have yet to prove that home ventilation system filters are effective at reducing these contaminants to safe levels, EECA recommends that the supply air of home ventilation systems be sourced from the outside, not from the roof cavity.
The New Zealand Building Code requires homes to have means of ventilation with outdoor air to maintain air purity. Ventilation systems that draw air from the roof space and not directly from outside do not comply with ventilation standard NZS4303:1990 "Ventilation for acceptable indoor air quality" and cannot be used to comply with the Building Code Acceptable Solution for ventilation.
Research recommends that you should not install this type of system for heating purposes
University of Otago research shows that the heat available from moving roof space air into your home (as the most common type of ventilation system does) does not provide significant benefits compared with what you need to properly heat a home in winter.
The research also found that pumping air from the roof space into the living area would often push internal temperatures away from the desired level, rather than toward it.
In summer, roof cavities quickly become excessively hot, and systems that pump roof space air into your house without a summer bypass will have to be turned off for extended periods in order to avoid overheating your house.

Balanced pressure heat recovery ventilation systems

Balanced pressure heat recovery ventilation systems are particularly suitable for homes in colder areas of the country, if they are already well heated and if they are reasonably airtight.
These systems have two fans for two separate air streams. One fan supplies fresh outdoor air into the house through several ceiling vents, while the exhaust fan extracts an equal volume of air from inside the house and discharges it to the outside. Some of the heat from the exhaust air is transferred to the incoming air in a heat exchange unit, usually located in the roof cavity.
Some products include additional features to utilise heat in the roof cavity when it is available on sunny winter days, or to avoid the incoming supply air being warmed up by the exhaust air during summer nights to assist with cooling.
To ventilate effectively, the air must be able to flow freely between the supply and exhaust vents inside the house, requiring gaps around or vents in internal doors. Care is also required to ensure that a ‘short circuit' route is not created between the supply and exhaust vents which would result in areas of the house being bypassed by the system.
In winter, the heat exchanger transfers a portion of the heat in the warm exhaust air to the cold supply air, thus reducing the heat loss associated with the ventilation. The overall effectiveness of the heat exchanger depends on two factors:

• having an airtight house, to ensure that uncontrolled ventilation losses are minimised so that almost all ventilation air passes through the heat exchanger
• having a temperature difference between the inside and outside air. The larger the difference the better the heat exchanger will work. In many areas of New Zealand the temperature difference will not be enough for the heat exchanger to make much difference.

Optional electrical heating unit add-ons

Some ventilation system suppliers offer the option of an electrical heating unit add-on, to provide some pre-heating of air coming from the roof cavity when it is cold. These are known as electric in-line duct heaters.
Most electric in-line duct heaters don't have sufficient capacity to meet a home's heating needs.
Like any other type of electrical heaters (except heat pumps), electrical in-line duct heaters are a relatively expensive and inefficient way to heat a home, particularly if you already have a more effective heater (like heat pump, wood or wood pellet burner, or flued gas heater).
Electric in-line duct heaters lose some heat through the ducts, so it's actually more efficient to use a heater directly in the room you want to heat.

http://www.energywise.govt.nz/your-home/ventilation/systems

Indoor Air Pollution: An Introduction for Health Professionals

Introduction

Indoor air pollution poses many challenges to the health professional. This booklet offers an overview of those challenges, focusing on acute conditions, with patterns that point to particular agents and suggestions for appropriate remedial action.
The individual presenting with environmentally associated symptoms is apt to have been exposed to airborne substances originating not outdoors, but indoors. Studies from the United States and Europe show that persons in industrialized nations spend more than 90 percent of their time indoors¹. For infants, the elderly, persons with chronic diseases, and most urban residents of any age, the proportion is probably higher. In addition, the concentrations of many pollutants indoors exceed those outdoors. The locations of highest concern are those involving prolonged, continuing exposure - that is, the home, school, and workplace.
The lung is the most common site of injury by airborne pollutants. Acute effects, however, may also include non-respiratory signs and symptoms, which may depend upon toxicological characteristics of the substances and host-related factors.
Heavy industry-related occupational hazards are generally regulated and likely to be dealt with by an on-site or company physician or other health personnel². This booklet addresses the indoor air pollution problems that may be caused by contaminants encountered in the daily lives of persons in their homes and offices. These are the problems more likely to be encountered by the primary health care provider.
Etiology can be difficult to establish because many signs and symptoms are nonspecific, making differential diagnosis a distinct challenge. Indeed, multiple pollutants may be involved. The challenge is further compounded by the similar manifestations of many of the pollutants and by the similarity of those effects, in turn, to those that may be associated with allergies, influenza, and the common cold. Many effects may also be associated, independently or in combination with, stress, work pressures, and seasonal discomforts.
Because a few prominent aspects of indoor air pollution, notably environmental tobacco smoke and "sick building syndrome," have been brought to public attention, individuals may volunteer suggestions of a connection between respiratory or other symptoms and conditions in the home or, especially, the workplace. Such suggestions should be seriously considered and pursued, with the caution that such attention could also lead to inaccurate attribution of effects. Questions listed in the diagnostic leads sections will help determine the cause of the health problem. The probability of an etiological association increases if the individual can convincingly relate the disappearance or lessening of symptoms to being away from the home or workplace.

Health Problems Caused By HEAVY METALS: AIRBORNE LEAD AND MERCURY VAPOR

Key Signs/Symptoms of
Lead Poisoning in Adults...

• gastrointestinal discomfort/constipation/anorexia/nausea
• fatigue, weakness
• personality changes
• headache
• hearing loss
• tremor, lack of coordination

... and in Infants and Small Children

• irritability
• abdominal pain
• ataxia
• seizures/ loss of consciousness
• (chronic) learning deficits
• hyperactivity, reduced attention span

Key Signs/Symptoms of Mercury Poisoning

• muscle cramps or tremors
• headache
• tachycardia
• intermittent fever
• acrodynia
• personality change
• neurological dysfunction

Diagnostic Leads

• Does the family reside in old or restored housing?
• Has renovation work been conducted in the home, workplace, school, or day care facility?
• Is the home located near a busy highway or industrial area?
• Does the individual work with lead materials such as solder or automobile radiators?
• Does the child have sibling, friend, or classmate recently diagnosed with lead poisoning?
• Has the individual engaged in art, craft, or workshop pursuits?
• Does the individual regularly handle firearms?
• Has the home interior recently been painted with latex paint that may contain mercury?
• Does the individual use mercury in religious or cultural activities?

Remedial Action

Wet-mop and wipe furniture frequently to control lead dust. Have professional remove or encapsulate lead containing paint; individuals involved in this and other high exposure activities should use appropriate protective gear and work in well-ventilated areas. Do not burn painted or treated wood.

Comment

Airborne Lead

Most health professionals are aware of the threat of lead (Pb) toxicity, particularly its long term impact on children in the form of cognitive and developmental deficits which are often cumulative and subtle. Such deficits may persist into adulthood⁴⁸. According to the American Academy of Pediatrics, an estimated three to four million children in the U.S. under age six have blood lead levels that could cause impaired development, and an additional 400,000 fetuses are at similar risk⁴⁹.

Lead toxicity may alternatively present as acute illness. Signs and symptoms in children may include irritability, abdominal pain, emesis, marked ataxia, and seizures or loss of consciousness. In adults, diffuse complaints -- including headache, nausea, anorexia (and weight loss), constipation, fatigue, personality changes, and hearing loss -- coupled with exposure opportunity may lead to suspicion of lead poisoning.
Lead inhibits heme synthesis. Since interruption of that process produces protoporphyrin accumulation at the cellular level, the standard screening method is investigation of blood lead (PbB) levels which reveal recent exposure to lead. Acute symptomology in adults is often associated with PbB at levels of 40 �g/dl or higher. There is good evidence for adverse effects of lead in very young children at much lower levels.^50,51 The Centers for Disease Control and Prevention has set 10 �g/dl as the level of concern⁵². Increased maternal Pb exposure has also been deemed significant in pregnancy, since an umbilical cord PbB of greater than 10 µg/dl has been correlated with early developmental deficits. If sufficiently high PbB levels are confirmed, chelation therapy may be indicated. Suspected low level lead contamination cannot be accurately identified by a erythrocyte protoporphyrin (EP) finger-stick test, but requires blood lead analysis.
Lead poisoning via ingestion has been most widely publicized, stressing the roles played by nibbling of flaking paint by infants and toddlers and by the use of lead-containing food ware (glass, and soldered metal-ceramic ware) by adults. Lead dust flaking or "chalking" off lead painted walls generated by friction surfaces is a major concern. Airborne lead, however, is also a worrisome source of toxicity. There is no skin absorption associated with inorganic lead.
Airborne lead outdoors, originating chiefly from gasoline additives, has been effectively controlled since the 1980s through regulation at the federal level. Much of this lead still remains in the soil near heavily trafficked highways and in urban areas, however, and can become airborne at times. It may enter dwellings via windows and doors, and contaminated soil can also be tracked inside.
Indoors, the chief source is paint. Lead levels in paints for interior use have been increasingly restricted since the 1950s, and many paints are now virtually lead free. But older housing and furniture may still be coated with leaded paint, sometimes surfacing only after layers of later, non-lead paint have flaked away or have been stripped away in the course of restoration or renovation. In these circumstances, lead dust and fumes can permeate the air breathed by both adults and children.
Additional sources of airborne lead include art and craft materials, from which lead is not banned, but the U.S. Consumer Product Safety Commission (CPSC) requires its presence to be declared on the product label if it is present in toxic amounts. Significant quantities are found in many paints and glazes, stained glass, as well as in some solder. Hazardous levels of atmospheric lead have been found at police and civilian firing ranges. Repair and cleaning of automobile radiators in inadequately ventilated premises can expose workers to perilous levels of airborne lead. The use of treated or painted wood in fireplaces or improperly vented wood stoves may release a variety of substances, including lead and other heavy metals, into the air.

Mercury Vapor

While old paint has been the most publicized source of airborne heavy metal (i.e., lead), new paint has emerged as a concern as well. A 1990 report detailed elevated levels of mercury in persons exposed to interior latex (water-based) paint containing phenylmercuric acetate (PMA)⁵³. PMA was a preservative that was used to prolong the product's shelf life.
Initial action by the U.S. Environmental Protection Agency resulted in the elimination of mercury compounds from indoor latex paints at the point of manufacture as of August 1990, with the requirement that paints containing mercury, including existing stocks originally designed for indoor use, be labeled or relabeled "For Exterior Use Only". As of September 1991, phenylmercuric acetate is forbidden in the manufacture of exterior latex paints as well. Latex paints containing hazardous levels of mercury may still remain on store shelves or in homes where they were left over after initial use, however.
An additional matter of concern, recently noted by the CPSC, is the sprinkling of mercury about the home by some ethnic/religious groups⁵⁴. According to the CPSC, mercury for this purpose is purveyed by some herbal medicine or botanical shops to consumers unaware of the dangers of the substance.

Health Problems Caused By SICK BUILDING SYNDROME

Key Signs/Symptoms

• lethargy or fatigue
• headache, dizziness, nausea
• irritation of mucous membranes
• sensitivity to odors

Diagnostic Leads

• Are problems temporally related to time spent in a particular building or part of a building?
• Do symptoms resolve when the individual is not in the building?
• Do symptoms recur seasonally (heating, cooling)?
• Have co-workers, peers noted similar complaints?

Remedial Action

Appropriate persons -- employer, building owner or manager, building investigation specialist, if necessary state and local government agency medical epidemiologists and other public health officials -- should undertake investigation and analysis of the implicated building, particularly the design and operation of HVAC systems, and correct contributing conditions. Persistence on the part of individuals and health care consultants may be required to diagnose and remediate the building problems.

Comment

The term "sick building syndrome" (SBS), first employed in the 1970s, describes a situation in which reported symptoms among a population of building occupants can be temporally associated with their presence in that building. Typically, though not always, the structure is an office building.
Generally, a spectrum of specific and nonspecific complaints are involved. Typical complaints, in addition to the signs and symptoms already listed, may also include eye and/or nasopharyngeal irritation, rhinitis or nasal congestion, inability to concentrate, and general malaise-complaints suggestive of a host of common ailments, some ubiquitous and easily communicable. The key factors are commonality of symptoms and absence of symptoms among building occupants when the individuals are not in the building.
Sick building syndrome should be suspected when a substantial proportion of those spending extended time in a building (as in daily employment) report or experience acute on-site discomfort. If is important, however, to distinguish SBS from problems of building related illness. The latter term is reserved for situations in which signs and symptoms of diagnosable illness are identified and can be attributed directly to specific airborne building contaminants. Legionnaires' Disease and hypersensitivity pneumonitis, for example, are building related illnesses.
There has been extensive speculation about the cause or causes of SBS. Poor design, maintenance, and/or operation of the structure's ventilation system may be at fault⁵⁵. The ventilation system itself can be a source of irritants. Interior redesign, such as the rearrangement of offices or installation of partitions, may also interfere with efficient functioning of such systems.
Another theory suggests that very low levels of specific pollutants, including some discussed in the preceding pages, may be present and may act synergistically, or at least in combination, to cause health effects. Humidity may also be a factor: while high relative humility may contribute to biological pollutant problems, an unusually low level -- below 20 or 30 percent -- may heighten the effects of mucosal irritants and may even prove irritating itself. Other contributing elements may include poor lighting and adverse ergonomic conditions, temperature extremes, noise, and psychological stresses that may have both individual and interpersonal impact.
The prevalence of the problem is unknown. A 1984 World Health Organization report suggested that as many as 30 percent of new and remodeled buildings worldwide may generate excessive complaints related to indoor air quality⁵⁶. In a nationwide, random sampling of U.S. office workers, 24 percent perceived air quality problems in their work environments, and 20 percent believed their work performance was hampered thereby⁵⁷.
When SBS is suspected, the individual physician or other health care provider may need to join forces with others (e.g., clinicians consulted by an individual's co-workers, as well as industrial hygienists and public health officials) to adequately investigate the problem and develop appropriate solutions.

Health Problems Caused By Two Long-Term Risks: ASBESTOS and RADON

Asbestos and radon are among the most publicized indoor air pollutants. Both are known human carcinogens. Their carcinogenic effects are not immediate but are evident only years, even decades, after prolonged exposure.

Asbestos

Once widely used in structural fireproofing, asbestos may be found predominantly in heating systems and acoustic insulation, in floor and ceiling tiles, and in shingles in many older houses. It was formerly used in such consumer products as fireplace gloves, ironing board covers, and certain hair dryers.
When asbestos-containing material is damaged or disintegrates with age, microscopic fibers may be dispersed into the air. Over as long as twenty, thirty, or more years, the presence of these fibers within the lungs may result in asbestosis (asbestos-caused fibrosis of the lung, seen as a result of heavy occupational exposure)⁵⁸, lung cancer and pleural or peritoneal cancer, or mesothelioma⁵⁹. For lung cancer, the effect of tobacco smoking in combination with asbestos exposure appears to be synergistic by approximately fivefold⁶⁰. Occupational exposure may also be associated with increased risk of gastrointestinal malignancies. Attention should be focused on those populations with continual exposure and documented health effects, e.g. maintenance workers.
Products and materials containing asbestos are not necessarily so labeled. Construction professionals or state or local environmental agencies may inspect and analyze suspect materials. Manufacturers of particular products may also be able to supply information.
The risk of disease depends on exposure to airborne asbestos fibers. Average levels in buildings are low, and the risk to building occupants is therefore low.
Removal of asbestos is not always the best choice to reduce exposure. The EPA requires asbestos removal only in order to prevent significant public exposure and generally recommends an in-place management program when asbestos has been discovered and is in good condition⁶¹.

Radon

Radon is the second leading cause of lung cancer, following smoking. Radon is odorless, colorless, and tasteless. It is a naturally occurring radioactive gas resulting from the decay of radium, itself a decay product of uranium. Radon in turn breaks down into radon decay products, short-lived radionuclides. These decay products, either free or attached to airborne particles, are inhaled, and further decay can take place in the lungs before removal by clearance mechanisms.
It is the emission of high-energy alpha particles during the radon decay process that increases the risk of lung cancer. While the risk to underground miners has long been known, the potential danger of residential radon pollution has been widely recognized only since the late 1970s, with the documentation of high indoor levels.
When radon decay products are inhaled and deposited in the lungs, the alpha emissions penetrate the cells of the epithelium lining the lung. Energy deposited in these cells during irradiation is believed to initiate the process of carcinogenesis. The EPA, the National Cancer Institute, the Centers for Disease Control and Prevention, and others estimate that thousands of lung cancer deaths per year are attributable to radon, based on data from epidemiologic studies of thousands of underground miners and from animal studies. Lung cancer is presently the only commonly accepted disease risk associated with radon.
Tobacco smoke in combination with radon exposure has a synergistic effect. Smokers and former smokers are believed to be at especially high risk. Scientists estimate that the increased risk of lung cancer to smokers from radon exposure is ten to twenty times higher than to people who have never smoked.
The EPA estimates that as many as six million homes throughout the country have elevated levels of radon. Since 1988, EPA and the Office of the Surgeon General have recommended that homes below the third floor be tested for radon.
Short term testing is the quickest way to determine if a potential problem exists, taking from two to ninety days to complete. Low-cost radon test kits are available by mail order, in hardware stores, and through other retail outlets⁶².
EPA recommends that consumers use measurement devices that are state-certified or have met the requirements of a proficiency program. For further information on EPA's former National Radon Proficiency Program (RPP) (EPA closed its National Radon Proficiency Program in 1998) visit our Radon web site www.epa.gov/radon/radontest.html  EPA also recommends that consumers use trained contractors who provide testing services. The most commonly used devices are charcoal canisters, electret ion detectors, alpha track detectors, and continuous monitors placed by contractors. Short term testing should be conducted in the lowest lived in area of the home, with the doors and windows shut. Long term testing can take up to a full year but is more likely to reflect the home's year round average radon level than short term testing. Alpha track detectors and electret ion detectors are the most common long-term testing devices.
Corrective steps include sealing foundation cracks and holes, and venting radon-laden air from beneath the foundation. Professional expertise should be sought for effective execution of these measures.

What is "multiple chemical sensitivity" or "total allergy"?

The diagnostic label of multiple chemical sensitivity (MCS) -- also referred to as "chemical hypersensitivity" or "environmental illness" -- is being applied increasingly, although definition of the phenomenon is elusive and its pathogenesis as a distinct entity is not confirmed. Multiple chemical sensitivity has become more widely known and increasingly controversial as more patients receive the label⁶³.
Persons with the diagnostic label of multiple chemical sensitivity are said to suffer multi-system illness as a result of contact with, or proximity to, a spectrum of substances, including airborne agents. These may include both recognized pollutants discussed earlier (such as tobacco smoke, formaldehyde, et al.) and other pollutants ordinarily considered innocuous. Some who espouse the concept of MCS believe that it may explain such chronic conditions as some forms of arthritis and colitis, in addition to generally recognized types of hypersensitivity reactions.
Some practitioners believe that the condition has a purely psychological basis. One study⁶³ reported a 65 percent incidence of current or past clinical depression, anxiety disorders, or somatoform disorders in subjects with this diagnosis compared with 28 percent in controls. Others, however, counter that the disorder itself may cause such problems⁶⁴, since those affected are no longer able to lead a normal life, or that these conditions stem from effects on the nervous system⁶⁵.
The current consensus is that in cases of claimed or suspected MCS, complaints should not be dismissed as psychogenic, and a thorough workup is essential. Primary care givers should determine that the individual does not have an underlying physiological problem and should consider the value of consultation with allergists and other specialists.

Who are "clinical ecologists"?

"Clinical ecology", while not a recognized conventional medical specialty, has drawn the attention of health care professionals as well as laypersons. The organization of clinical ecologists-physicians who treat individuals believed to be suffering from "total allergy" or "multiple chemical sensitivity" -- was founded as the Society for Clinical Ecology and is now known as the American Academy of Environmental Medicine. Its ranks have attracted allergists and physicians from other traditional medical specialties⁶⁶.

What are ionizers and other ozone generating air cleaners?

Ion generators act by charging the particles in a room so that they are attracted to walls, floors, tabletops, draperies, occupants, etc. Abrasion can result in these particles being resuspended into the air. In some cases these devices contain a collector to attract the charged particles back to the unit. While ion generators may remove small particles (e.g., those in tobacco smoke) from the indoor air, they do not remove gases or odors, and may be relatively ineffective in removing large particles such as pollen and house dust allergens. Although some have suggested that these devices provide a benefit by rectifying a hypothesized ion imbalance, no controlled studies have confirmed this effect.
Ozone, a lung irritant, is produced indirectly by ion generators and some other electronic air cleaners and directly by ozone generators. While indirect ozone production is of concern, there is even greater concern with the direct, and purposeful introduction of a lung irritant into indoor air. There is no difference, despite some marketers' claims, between ozone in smog outdoors and ozone produced by these devices. Under certain use conditions ion generators and other ozone generating air cleaners (see www.epa.gov/iaq/pubs/ozonegen.html) can produce levels of this lung irritant significantly above levels thought harmful to human health. A small percentage of air cleaners that claim a health benefit may be regulated by FDA as a medical device. The Food and Drug Administration has set a limit of 0.05 parts per million of ozone for medical devices. Although ozone can be used in reducing odors and pollutants in unoccupied spaces (such as removing smoke odors from homes involved in fires) the levels needed to achieve this are above those generally thought to be safe for humans.

Can other air cleaners help?

Ion generators and ozone generators (see www.epa.gov/iaq/pubs/ozonegen.html) are types of air cleaners; others include mechanical filter air cleaners, electronic air cleaners (e.g., electrostatic precipitators), and hybrid air cleaners utilizing two or more techniques. Generally speaking, existing air cleaners are not appropriate single solutions to indoor air quality problems, but can be useful as an adjunct to effective source control and adequate ventilation. Air cleaning alone cannot adequately remove all pollutants typically found in indoor air.
The value of any air cleaner depends upon a number of factors, including its basic efficiency, proper selection for the type of pollutant to be removed, proper installation in relation to the space, and faithful maintenance. Drawbacks, varying with type, may include inadequate pollutant removal, re-dispersement of pollutants, deceptive masking rather than removal, generation of ozone, and unacceptable noise levels.
[At the time of this publication,] the EPA and CPSC had not taken a position either for or against the use of these devices in the home⁶⁷. For more information on ozone generators, read the fact sheet: Ozone Generators That Are Sold As Air Cleaners (see www.epa.gov/iaq/pubs/ozonegen.html). The purpose of this document (which is only available via this web site) is to provide accurate information regarding the use of ozone-generating devices in indoor occupied spaces. This information is based on the most credible scientific evidence currently available.

Should I have my ducts cleaned?

As awareness of the importance of indoor air quality grows, more people are looking at duct cleaning as a way to solve indoor air quality problems. Individuals considering having ducts cleaned should determine that contaminated ducts are the cause of their health problems. Even when contaminants are found in ducts, the source may lie elsewhere, and cleaning ducts may not permanently solve the problem. The duct cleaning industry is expanding to meet demand, using extensive advertising to encourage people to use their services.
Individuals who employ such services should verify that the service provider takes steps to protect individuals from exposure to dislodged pollutants and chemicals used during the cleaning process. Such steps may range from using HEPA filtration on cleaning equipment, providing respirators for workers, and occupants vacating the premises during cleaning.

• Since this publication was released, EPA has released the document "Should You Have the Air Ducts in Your Home Cleaned," EPA-402-K-97-002, ISBN 0-16-042730-4, October 1997.

Can carpet make people sick?

Like many other household products and furnishings, new carpet can be a source of chemical emissions. Carpet emits volatile organic compounds, as do products that accompany carpet installation such as adhesives and padding. Some people report symptoms such as eye, nose and throat irritation; headaches; skin irritations; shortness of breath or cough; and fatigue, which they may associate with new carpet installation. Carpet can also act as a "sink" for chemical and biological pollutants including pesticides, dust mites, and fungi.
Individuals purchasing new carpet should ask retailers for information to help them select lower emitting carpet, cushion, and adhesives. Before new carpet is installed, they should ask the retailer to unroll and air out the carpet in a clean, well-ventilated area. They should consider leaving the premises during and immediately after carpet installation or schedule the installation when the space is unoccupied. Opening doors and windows and increasing the amount of fresh air indoors will reduce exposure to most chemicals released from newly installed carpet. During and after installation in a home, use of window fans and room air conditioners to exhaust fumes to the outdoors is recommended. Ventilation systems should be in proper working order, and should be operated during installation, and for 48 to 72 hours after the new carpet is installed.
Individuals should request that the installer follow the Carpet and Rug Institute's installation guidelines⁶⁸. If new carpet has an objectionable odor, they should contact their carpet retailer. Finally, carpet owners should follow the manufacturer's instructions for proper carpet maintenance.

Can plants control indoor air pollution?

Recent reports in the media and promotions by the decorative houseplant industry characterize plants as "nature's clean air machine", claiming that National Aeronautics and Space Administration (NASA) research shows plants remove indoor air pollutants. While it is true that plants remove carbon dioxide from the air, and the ability of plants to remove certain other pollutants from water is the basis for some pollution control methods, the ability of plants to control indoor air pollution is less well established. Most research to date used small chambers without any air exchange which makes extrapolation to real world environments extremely uncertain. The only available study of the use of plants to control indoor air pollutants in an actual building could not determine any benefit from the use of plants⁶⁹. As a practical means of pollution control, the plant removal mechanisms appear to be inconsequential compared to common ventilation and air exchange rates. In other words, the ability of plants to actually improve indoor air quality is limited in comparison with provision of adequate ventilation.
While decorative foliage plants may be aesthetically pleasing, it should be noted that over damp planter soil conditions may actually promote growth of unhealthy microorganisms.





http://www.epa.gov/iaq/pubs/hpguide.html

Interior Pollution Sources

Interior pollution sources is a larger category encompassing items or materials
often found inside the home that lead to significant health issues when inhaled. Most of these hazards
can be classified as a building material, combustion product, or chemical.
The main pollutants produced by building materials are formaldehyde, asbestos, and lead.
Formaldehyde is a chemical found in found in many pressed wood products as well as some
insulations and glues. Asbestos is a fibrous mineral found in older buildings as fire-proofing or acoustic
insulation material. Lead is an elemental pollutant found in some paints as well as contaminated soil,
dust, and water. Inhalation of these pollutants can lead to ear, nose, and throat irritation; cancer, and
damage to the central nervous system, kidneys, and blood.
Combustion products in the home include: kerosene heaters, furnaces, stoves, and fireplaces. The
main pollutants produced as combustion byproducts are carbon monoxide, nitrogen oxides, respirable
particles, and formaldehyde (see above). Carbon monoxide and nitrogen oxides are colorless, odorless,
tasteless gas byproducts and respirable particles are small particulate byproducts produced during
the combustion process. Inhalation of these pollutants can lead to respiratory tract irritation and
infection, aggravation of asthma and respiratory diseases, cancer, and even death by asphyxiation.
Numerous types of chemicals each with different purposes can be found around the house. Volatile
Organic Compounds (VOC’s) are the main pollutant produced by chemicals and can be found in
cleaners, paints, paint strippers, disinfectants, wood preservatives, and automotive products. Pesticides
are a type of chemical used to kill household pests and can also be used on lawns and gardens and are
classified as semi-volatile organic compounds. Inhalation of VOCs or pesticides causes eye, nose, and
throat irritation, headaches, nausea, and damage to the liver, kidneys, and central nervous system. For
more specific information regarding any pollutants mentioned here, visit the virtual health house.

 Tips to reduce exposure to interior pollution:
• To reduce formaldehyde exposure, use
exterior grade pressed wood products
containing phenol resins.
• Leave undamaged asbestos products alone,
and contact a professional if any needs to
be removed.
• Keep children play areas dust free and
clean as possible to reduce lead exposure.
• Do not remove lead paint yourself, if it
needs to be removed hire a professional.
• Install a carbon monoxide detector/ alarm.
• To prevent exposure to combustion byproducts,
vent all furnaces outdoors or
open windows and doors when using an
un-vented heater.
• Change filters on central heating and
cooling systems according to manufactures
instructions to reduce particulate pollution.
• Hire a professional for an annual
maintenance routine for all combustion
products that should include: tune-ups,
check for heat exchanger leakage, evidence
of start-up spillage, and condensation in
chimneys.
• Keep all household chemical products out
of reach of children and pets.
• Use household chemical products
according to manufacturers instructions,
avoid mixing products unless specified on
labels, and have adequate ventilation when
using them.
• Use non-chemical pesticide methods when
possible


http://www.healthhouse.org/tipsheets/IndoorPollutantSources.pdf

Branz Guide

http://www.branz.co.nz/cms_show_download.php?id=c10d1fddca1b50791943a98ccc59a0eaff8f1124