Children who breathe polluted air may suffer long-term lung damage, according to preliminary data from a 10-year study of 5,000 children living in a dozen communities throughout California that was published in the American Journal of Respiratory and Critical Care Medicine. The study, undertaken for the California Air Resources Board, also found that boys were more susceptible to smog, whereas girls were more likely to suffer adverse effects from soot.
Under the Clean Air Act of 1970, Congress mandated the U.S. Environmental Protection Agency (EPA) to set maximum levels for six airborne pollutants: carbon monoxide, lead, ozone, particulate matter (there is a separate standard for particles up to 10 micrometers and for those up to 2.5 micrometers), nitrogen dioxide, sulfur dioxide. For each type of pollutant, the EPA sets two standards. The primary standard is meant to protect public health, including the health of "sensitive" people, such as asthmatics, children and the elderly. Secondary standards are meant to protect public welfare, including decreased visibility, and damage to crops, animals and buildings.
Air pollution, especially ground-level ozone, can exacerbate asthma symptoms, and can trigger an attack by increasing sensitivity to airborne allergens. Children may be at higher risk from air pollution than adults because their lungs and immune systems are still developing; they also breathe more rapidly and deeply than adults do, so a greater dose of pollutants enters into their lungs. The elderly may also vulnerable to the ill effects of elevated levels of airborne pollutants because they tend to have chronic heart and lung conditions, and may be at increased risk of respiratory infections, such as influenza and pneumonia.
Scientific studies show that air pollution causes:
In 1997, approximately 52.6 million people lived in counties with air quality levels that exceeded the EPA’s National Ambient Air Quality Standard for at least one airborne pollutant (typically, ozone). These counties are primarily on the East Coast from Maine to Maryland, in central and Southern California, the Gulf coast of Texas on the Louisiana border and along the shores of Lake Michigan in Wisconsin, Illinois and Indiana. Here is a primer on the three types of air pollution that affect the largest numbers of people in the US, and precautions you should take when the air outside is not fit to breathe.
Carbon Monoxide Chokes Your Cells
Automobile emissions are the main source of carbon monoxide (CO) in the air. More than 9.7 million people live in areas that regularly exceeded Federal limits in 1997. CO displaces the oxygen in your red blood cells. Consequently, less oxygen is carried to the cells in your body; the heart and lungs are the most adversely affected. Some 3 million people who suffer congestive heart failure (a life-threatening chronic condition in which the heart can not pump out all the blood that enters the chambers) may be extremely vulnerable to the effects of CO. Studies show that even Federally permissible levels of CO could intensify symptoms enough to require hospitalization, and that high exposure to the pollutant for even a short period can lower the amount of exertion it takes for people with coronary artery disease to experience chest pain (angina).
The Problem With Particulates
Diesel bus, truck and auto emissions, factory and utility smokestacks, and wood burning are common sources of man-made particulate air pollution. Soil erosion, brush or forest fires and plant matter (pollen, for instance) are significant natural sources of air-borne soot. The EPA estimates that over 7.9 million people in the US were exposed to unhealthful levels of particulate pollution in 1997.
People living in areas with the highest concentration of particulates have a 15% to 17% increased risk of death compared with those who live in the least polluted areas, according to one study by the Harvard School of Public Health in Boston. The 7-year study, which followed 552,138 people in 151 cities across the nation found an increased risk of death from all causes, as well as from heart and lung diseases, associated with particulate pollution. Interestingly, their findings were consistent for smokers and non-smokers alike.
Smothered By Smog
Ground-level ozone (or smog) is created when nitrogen oxide and volatile organic compounds (VOCs), react in the presence of heat and sunlight. The ingredients that make up the thick, yellowish pea soup that blankets our cities come from motor vehicles, industrial smokestacks, paints and solvents—and even Mother Nature (plants produce many VOCs). Add sunlight and hot, stagnant air and you have the perfect recipe for smog. The worst exposures occur on summer afternoons in parts of the country with the right weather conditions and a large volume of motor vehicle traffic.
More than 47.9 million Americans lived in areas that failed to meet government standards for ozone in 1997. Smog can irritate the eyes and bronchial passages, cause shortness of breath, wheezing, coughing and chest tightness. The pollutant may also worsen symptoms of asthma, bronchitis and emphysema. Even healthy people may suffer breathing difficulties exercising outdoors when there’s an ozone alert. The severity of these effects increases with the concentration of ozone in the air, the length of exposure and the amount breathed into the lungs (when you exercise, you breathe faster, and more ozone gets into your airways and lungs).
Keep A Weather-Eye On The PSI
The best way to protect yourself from adverse health problems caused by poor air quality is to keep tabs on the Pollutant Standards Index (PSI) in your area. The PSI index is a composite of the five most common air pollutants (lead is the only exception), and is meant to provide a "snapshot" of daily levels of air pollution in metropolitan areas that have 200,000 or more inhabitants.
You can get the PSI from your state or local air quality agency (check the "blue pages" of the phone book), EPA regional office or the American Lung Association national help line (800-LUNG-USA). Remember that the PSI can change throughout the day and from region to region because some airborne pollutants can migrate from one area to another. Here’s how it works: Every day the EPA measures the concentrations of pollutants in a community’s air and converts each reading to a number on a scale of 0 to 500. On this scale, up to 100 means that the concentration of an airborne pollutant is in compliance with the Clean Air Act; above 100, and the concentration is "unhealthful". The highest of the five numbers typically becomes the official PSI for a given metropolitan area. In most US communities, PSI levels generally fall between 0 and 100. Readings exceeding 100 are likely to occur only a few times a year, and even metropolitan areas that have severe air pollution problems and regularly have PSI levels above 100, will rarely exceed 200.
The EPA recommends that senior citizens and those who have chronic lung or breathing problems take these precautions when levels of airborne pollutants are high. The following table provides guidelines.
| Index Value | Near Term Health Effects | Precautions | |
| Up to 50 (Good) |
None for the general population | None required. | |
| 50 – 100 (Moderate) |
Few or none for the general population | None Required | |
| 100 – 200 (Unhealthful) |
Mild aggravation of symptoms among susceptible people, with irritation symptoms in the healthy population | People with existing heart or respiratory ailments should reduce physical exertion and outdoor activity. Other should reduce vigorous outdoor activity. | |
| 200 – 300 (Very Unhealthful) |
Significant aggravation of symptoms and decreased exercise tolerance in people with heart or lung disease; widespread symptoms in the healthy population. | Elderly and people with heart or lung disease should stay indoors and reduce physical activity. Others should avoid vigorous outdoor activity. | |
| Above 300 (Hazardous) |
Early onset of certain diseases and significant aggravation of symptoms and decreased exercise tolerance in healthy people. At levels above 400, premature death of ill and elderly people may result. Healthy people experience adverse symptoms during normal activities. | Elderly and people with existing diseases should stay indoors and avoid physical exertion. At levels above 400, everyone should remain indoors, keeping windows and doors closed, and minimize physical exertion. | |