Reducing Indoor Air Pollution
A Serious Public Health Problem
May 2, 2001

This page updated September 20, 2017


Indoor Air Pollution: A Serious Public Health Problem

We spend most of our time indoors surrounded by sources of air pollution: consumer products, gas appliances, building materials, cigarettes, and furniture can all contribute to the problem. Yet, the toxic emissions from many of these sources are not controlled or are only partially controlled by federal, state, or local laws.
This brochure will tell you about indoor air pollution and what the California Air Resources Board (ARB) is doing about it.
Evaluating the Risk
In a 1987 study, the U.S. Environmental Protection Agency (U.S. EPA) ranked indoor air pollution fourth in cancer risk among the 13 top environmental problems analyzed. Indoor radon ranked first. What factors contribute to the high risk from indoor air pollution?
First, people spend most of their time indoors. A recent ARB-sponsored study found that Californians spend an average of 87 percent of their 24-hour day indoors. If pollutants are present indoors, people will almost certainly inhale them.
Second, indoor air pollutant levels are often higher than those outdoors. Research by the ARB, the U.S. EPA and others has shown that indoor levels of some pollutants, such as formaldehyde, chloroform, and styrene, range from two to 50 times higher than outdoor levels. Exposure to pollutants such as environmental tobacco smoke and radon occurs almost entirely indoors. For most of us, the amount of air pollution that we breathe is primarily determined by what is in the indoor air.
What is Indoor Air Pollution?
Indoor air pollution consists of toxic gases or particles that can harm your health. These pollutants can build up rapidly indoors to levels much higher than those usually found outdoors. This is especially true if large amounts of a pollutant are released indoors. Moreover, "tighter" construction in newer homes can prevent pollutants from escaping to the outdoors.

Sources and Potential Health Effects of Indoor Air Pollutants


Major Indoor Sources

Potential Health Effects*

Tobacco Smoke

Cigarettes, Cigars and Pipes

Respiratory Irritation, Bronchitis and
Pneumonia in Children; Emphysema,
Lung Cancer and Heart Disease

Carbon Monoxide

Unvented or Malfunctioning
Gas Appliances, Wood Stoves
and Tobacco Smoke

Headache, Nausea, Angina, Impaired
Vision and Mental Functioning,
Fatal at High Concentrations

Nitrogen Oxides

Unvented or Malfunctioning
Gas Appliances

Eye, Nose and
Throat Irritation; Increased
Respiratory Infections in Children

Organic Chemicals

Aerosol Sprays, Solvents, Glues,
Cleaning Agents, Pesticides, Paints,
Moth Repellents, Air Fresheners,
Drycleaned Clothing and Treated Water

Eye, Nose and Throat Irritation;
Headaches; Loss of Coordination;
Damage to Liver, Kidney and
Brain; Various Types of Cancer


Pressed Wood Products Such as
Plywood and Particleboard; Furnishings;
Wallpaper; Durable Press Fabrics

Eye, Nose and
Throat Irritation; Headache;
Allergic Reactions; Cancer

Respirable Particles

Cigarettes, Wood Stoves, Fireplaces,
Aerosol Sprays and House Dust

Eye, Nose and Throat Irritation;
Increased Susceptibility to
Respiratory Infections and
Bronchitis; Lung Cancer

Biological Agents
(Bacteria, Viruses, Fungi,
Animal Dander, Mites)

House Dust; Pets; Bedding;
Poorly Maintained Air Conditioners,
Humidifiers and Dehumidifiers; Wet
or Moist Structures; Furnishings

Allergic Reactions; Asthma;
Eye, Nose and Throat Irritation;
Humidifier Fever, Influenza
and Other Infectious Diseases


Damaged or Deteriorating Insulation, Fireproofing and Acoustical Materials

Asbestosis, Lung Cancer,
Mesothelioma and Other Cancers


Sanding or Open-Flame Burning
of Lead Paint; House Dust

Nerve and Brain Damage,
Particularly in Children; Anemia;
Kidney Damage; Growth Retardation


Soil Under Buildings,
Some Earth-Derived Construction
Materials and Groundwater

Lung Cancer


Depends on factors such as the amount of pollutant inhaled, the duration of exposure and susceptibility of the individual exposed.

Health Effects
The effects of indoor air pollutants range from short-term effects - eye and throat irritation - to long-term effects - respiratory disease and cancer. Exposure to high levels of some pollutants, such as carbon monoxide, can even result in immediate death. Also, some indoor pollutants can magnify the effects of other indoor pollutants. Based on cancer risk alone, federal scientists have ranked indoor air pollution as one of the most important environmental problems in the United States.
"Sensitive" Groups
Many groups are especially susceptible to the health effects of indoor pollutants. These include infants and the elderly, those with heart and lung diseases, people with asthma, and individuals who have developed extreme sensitivity to chemicals. Unfortunately, these are the people who often spend the most time indoors.
Economic Impacts
The economic impacts of indoor pollution - including health care costs, lost productivity, legal costs, and human welfare impacts - have been estimated at billions of dollars each year.
What Can You Do About Indoor Air Pollution?
The most effective way to protect your family and yourself from indoor air pollution is to prevent or minimize the release of pollutants indoors in the first place.
Use Products Safely
Products such as cleaning agents, paints, and glues should be used outdoors whenever possible. Directions on the label should be followed carefully. If the product must be used indoors, lots of ventilation should be provided. Also, it may be possible to use safer consumer products, such as baking soda instead of harsher cleaners, or products in solid or liquid form rather than aerosol sprays.
Restrict Smoking
Restricting cigarette smoking to outdoor areas is especially important because cigarette smoke contains many toxic pollutants. It is harmful to both smokers and nonsmokers.
Use Appliances Properly
Use gas appliances, wood stoves, and fireplaces only as intended. Gas stoves should never be used to heat the house since high pollutant levels can result. Wood stoves and fireplaces should only be used to burn properly sized and aged wood, since other types of fuel may emit toxic compounds.
These combustion devices pollute less when properly maintained. Annual inspections and cleaning by your gas company's service personnel or by other qualified individuals will help reduce pollution and save energy.
Select Building Materials and Furniture Carefully
Many products, including some types of plywood and particleboard, emit significant amounts of formaldehyde or other gaseous pollutants. Try to avoid those products if possible.
You might request that new carpets or furniture be aired out by the manufacturer or distributor prior to delivery. Otherwise, you may want to air them in your garage or yard before bringing them inside.
Practice Good Housekeeping
Proper storage of solvents and frequent housecleaning to remove dust and molds are necessary steps in maintaining good indoor air quality.
Provide Adequate Ventilation
Adequate ventilation is another easy and effective way to maintain good indoor air quality, although it may not completely remove all pollutants. Increase ventilation by opening windows and doors when the weather permits. This is particularly important when using products or engaging in activities that may generate pollutants. Kitchen and bathroom exhaust fans that are properly vented to the outdoors are very effective at removing pollutants generated during cooking and showering. For effective ventilation while conserving energy during extreme weather, consider installing a heat recovery ventilator.
Opportunities for Further Action

The California Air Resources Board, working with representatives from other State and local agencies, is committed to reducing Californian's exposures to indoor air pollution by:

  • Developing Indoor Air Quality Guidelines

  • Promoting Preventive Measures

  • Working with Other Goverment Agencies and Interested Groups to Reduce Exposure
    to Indoor Air Pollution

  • Increasing Public Education, and

  • Increasing Research into the Health Risks, Economic Impacts and Best Mitigation Measures
    for Indoor Air Pollution.
How You Can Help
Follow the suggestions in this brochure. Educate yourself, your family, and your friends. Support the control of sources of indoor air pollution.
For further information and to obtain any of the reports mentioned in this brochure, please contact:

Indoor Exposure Assessment Program
Research Division
California Air Resources Board
P.O. Box 2815
Sacramento, CA 95812

(916) 445-0753

Indoor Air Quality Program
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