The symptoms are familiar to all those who live in cities where the air is polluted: aching lungs, wheezing, coughing, headache. Millions of residents of the South Coast Basin (which includes Los Angeles, Orange, and parts of San Bernardino and Riverside counties) breathe dirty air some one-third the days of the year. Ozone levels here, or what most refer to as smog, are often twice the federal health standard. In 1997, the standard was exceeded on 98 days at one or more Basin locations, most frequently in the east San Gabriel Valley. What does all of this polluted air do to the body? The answer depends on the situation. How long a person is exposed to pollution, the type and concentration, the place, time and day, temperature, weather and more. But one thing is certain: Smog is harmful to your health. Lungs are ozone’s primary target. Studies on animals show that ozone damages cells in the lung’s airways, causing inflammation and swelling. It also reduces the respiratory system’s ability to fight infection and remove foreign particles. Ozone may pose a particular health threat to those who already suffer from respiratory problems such as asthma, emphysema and chronic bronchitis. About 10% of the basin’s approximately 14 million residents fit into this category. Ozone may also pose a health threat to the young, elderly and cardiovascular patients. Ozone affects healthy people as well. In 1990, the State Air Resources Board established a new health advisory level in response to mounting evidence that smog affects healthy, exercising adults at lower levels than previously believed. Now, a health advisory is issued at .15 parts per million (on the pollutant standards index) before a first stage smog alert is called when ozone levels reach .20 ppm. During a health advisory, everyone, including healthy adults and children are advised to avoid prolonged, vigorous outdoor exercise. Susceptible individuals, including those with heart or lung disease, should avoid outdoor activities until the advisory is cancelled. Sources of Smog The sources of pollution include emissions from on-road vehicles, non-road vehicles like planes, ships and trains, industries, and even small businesses and households where polluting products are used. Ozone, an invisible gas, is not emitted directly into the air, but forms when nitrogen oxides from fuel combustion and volatile organic gases from evaporated petroleum products react in the presence of sunshine. Ozone levels are highest during the warm months when there is strong sunshine, high temperatures and an inversion layer. Nitrogen oxides are produced when fossil fuels are burned in motor vehicles, power plants, furnaces and turbines. Carbon monoxide is a by-product of combustion that comes almost entirely from motor vehicles. Fine particulates, which are emitted directly as smoke and diesel soot and form in the air out of nitrogen oxides and sulfur oxides, obscure visibility and can be inhaled deep into the lungs. Historical Perspective During the early years of World War II, Los Angeles residents began to realize the consequences of an increasingly industrialized area. Investigations began to determine the cause of resident’s eye irritation, crop damage, severe reductions in visibility and the rapid deterioration of rubber products. “Smog” became a familiar word and everyday presence and scientists and medical personnel began to look at its effects on public health. In the mid-1950s, the state of California’s Public Health division started to step up its efforts to define the problem of how and where smog forms, as well as address the health concerns associated with exposure to smog. Ozone levels were reaching peaks of .68 parts per million, more than six times the federal health standard. Early efforts to study the health effects of exposure to air pollution focused on acute exposure episodes. Only recently have the long-term exposure effects been addressed. In a 1956 survey sent out by the Los Angeles County Medical Association, physicians reported the following: F 94.7% recognized the existence of a “smog complex” involving eye irritation, irritation of the respiratory tract, chest pains, cough, shortness of breath, nausea and headache; F 56.1% have “authenticated cases of individuals leaving this area solely because of smog”; F 43.3% have recommended that patients move from the area on account of the effect of smog on their health; F 86.7% have observed that patients with respiratory diseases are more susceptible to smog than healthy adults; F 68% believe that patients with cardiac diseases are more susceptible to smog than healthy adults; F 89.6% have noticed patients with allergies are more susceptible to smog than healthy adults; and F 81.3% believe that smog is a contributing factor to cancer of the lungs and air passages. Children and smog A 1984 study conducted by Dr. Kay Kilburn, M.D., Professor of Medicine at USC showed that children raised in the South Coast Air Basin suffer a 10% to 15% decrease in lung function compared to children who grow up where the air is less polluted. The California Air Resources Board has concluded that “since the lungs of children are not fully developed, early damage to the respiratory tract could increase the risk of respiratory disease in adult life.” Jane Hall’s 1989 study on the health effects of air pollution on residents of the South Coast Air Basin estimated that school-age children, who represent only 20% of the basin’s population, experience more than 40% of the symptoms associated with ozone. Because of their physiology, children are much more likely than adults to develop smog-related lung damage. For their body size, children inhale several times more air than adults, and they breathe faster, particularly during strenuous physical activity. In addition, they spend more time outdoors than any other segment of the population according to the AQMD study. Dr. Robert F. Phalen, Ph.D., professor of community and environmental medicine and director of the Air Pollution Health Effects Laboratory at the University of California, Irvine, says that when children exercise, they tend to breathe through their mouths. According to Phalen, mouth-breathing bypasses the natural filtering of air pollutants by the nose and allows large volumes of polluted air to affect the more sensitive areas of children’s lungs which are still developing. Studies show that children exposed to summer ozone pollution year in, year out, have a greater susceptibility to respiratory infections because chronic exposure to smog impairs their immune system. Research findings also suggest that, even if children do not show symptoms while exercising in unhealthful air, they are likely to suffer a loss in lung function compared to youngsters who grow up where the air is less polluted. Air quality standards and health State and federal governments have set health standards for pollutants, specifying levels beyond which the air is unhealthful. California’s state standards for air pollutants are more stringent than the federal government’s. It is up to each individual state to determine if they want to set tougher standards. Standards are set to provide an adequate margin of safety in the protection of public health. Under the federal Clean Air Act, EPA must base standards solely on health considerations and not economics or technology. The standards for pollutants in California include: Ozone (one-hour average) Federal = Not to exceed .12 ppm (parts per million) more than one day per year. That means no more than .12 of a volume of ozone per million volumes of air. State = Not to equal or exceed .09 ppm Carbon Monoxide Federal = Not to exceed 35 ppm for one-hour average; 9.4 ppm for eight-hour average State = Not to exceed 20 ppm for one-hour average; 9 ppm for eight-hour average PM 10 (particles 10 micrometers millionths of a meter or less in diameter) Federal = 150 micrograms per cubic meter of air for 24-hour average (arithmetic mean); 50 micrograms per cubic meter of air for annual average (arithmetic mean) State = 50 micrograms per cubic meter of air for 24-hour average; 30 micrograms per cubic meter of air for annual average (geometric mean). Nitrogen Dioxide Federal = .52 ppm for one-hour average State = .25 for one-hour average Smog episodes and what they mean Various levels of smog episodes are reported for the pollutant ozone. The declaration of a first, second or third stage smog alert is based on the degree of health risk. The protective actions help to reduce exposure to unhealthful levels of ozone, but those who are especially sensitive should contact their physician for more specific advice. Generally, in the event of a smog alert, outdoor activities should be scheduled for morning or early evening hours to avoid the mid-day peak when ozone levels are at their highest. Hourly updates on air pollution levels are available to the public through the AQMD’s toll-free, taped telephone information service. The number for residents of Los Angeles is (800) 242-4022. AQMD also provides a live, toll-free line at (800) 242-4666, where callers can ask specific questions about air pollution conditions. Information for this article was provided by the AQMD.