WASHINGTON, DC--There's good news about air pollution: It has substantially decreased over the past few decades. The bad news is that levels of invisible air pollutants, especially ozone, are still unacceptably high in many urban areas and have become quite bad even in regions without a reputation for air pollution.

Those were the main messages contained in State of the Air: 2000, the first annual "report card" on America's air quality by the American Lung Association (ALA).[1] The report assigns cities and counties a grade of A through F based on the air quality index developed by the federal Environmental Protection Agency (EPA).

"About half the counties that had ozone air quality monitors received an F for air quality," reported Ron White, Assistant Vice President for National Policy at the ALA, in an interview with RESPIRATORY REVIEWS. He added that the total population of the counties that received an F is more than 132 million people.

Among this population are large groups of people at increased risk for respiratory sequelae from air pollution, including 16 million elderly (over age 65 years) and 7 million people with asthma, more than a quarter of whom are children. Another 7 million inhabitants have chronic bronchitis.

State of the Air: 2000 focuses on ozone air pollution because ozone is pervasive and harmful. At levels commonly found in American cities, ozone penetrates airway cells, causing redness and swelling, decreased elasticity and scarring of airway tissue, cellular fluid seepage into the lungs, and greater susceptibility to infection. Not surprisingly, elevated ozone levels are associated with impaired lung function, increased emergency department visits for respiratory diseases, and even death.[2-4]

Reducing ozone levels not only helps to eliminate the ozone as a source of lung damage, it also leads to reductions in other air pollutants, such as fine particulate matter and toxic organic compounds (see box).

GRADING AIR QUALITY

To create its grading system, the ALA obtained air quality data from the EPA's Aerometric Information Retrieval System, a database of nationwide ozone measurements. Using data for 1996 through 1998, the most recent years available, the highest eight-hour daily maximum ozone level for the counties and cities in the database was determined.

The grade for each county and city was based on a weighted average for the number of days its eight-hour daily maximum ozone level placed it in the "unhealthy" categories of the EPA's air quality index (Table 1). An A grade corresponded with a weighted average of zero, a B with 0.3 to 0.9, a C with 1.0 to 2.0, a D with 2.1 to 3.2, and an F with 3.3 or higher.

NEW AREAS OF HIGH POLLUTION

The ALA used the grades to generate air quality rankings. "It's surprising how many areas not previously thought of as having high air pollution were poorly ranked," Mr. White remarked. Examples include Atlanta; Nashville; Memphis; Birmingham, Alabama; and Charlotte, North Carolina. All of these locations received an F for air quality. These cities had the dubious distinction of being on the ALA's list of the 25 American cities with the worst ozone pollution (Table 2). The poor rankings of these and other cities in the Southeast suggest a worsening ozone pollution problem in that region, Mr. White pointed out.

Though its pollution problem has gotten better, Los Angeles still tops the list of America's most ozone-polluted cities. Following it are five other California cities: Bakersfield, Fresno, Visalia, Tulare, and Porterville. In fact, nine of the 25 cities with the worst ozone pollution were in California. However, pollution is a national problem and affects cities and counties of all sizes, Mr. White noted. In addition, Houston's one-hour ozone concentration exceeded the levels in Los Angeles.

Ozone pollution is generally lowest in the Pacific Northwest and Central states. For example, Spokane and Bellingham, Washington; Cedar Rapids and Des Moines, Iowa; Colorado Springs, Colorado; and Duluth, Minnesota, all received an A for air quality.

"We must keep moving forward aggressively on the national, state, and local levels with air pollution control," Mr. White concluded. "Though we've made substantial progress, this is not the time to scale back our efforts to address air pollution."

--Timothy Begany

References
1.State of the air: 2000. New York, NY: American Lung Association; 2000.
2. Fauroux B, Sampil M, Quenel P, Lemoullec Y. Ozone: a trigger for hospital pediatric asthma emergency room visits. Pediatr Pulmonol. 2000; 30:41-46.
3. Tenias JM, Ballester F, Rivera ML. Association between hospital emergency visits for asthma and air pollution in Valencia, Spain. Occup Environ Med. 1998;55:541-547.
4. Weisel CP, Cody RP, Lioy PJ. Relationship between summertime ambient ozone levels and emergency department visits for asthma in central New Jersey. Environ Health Perspect. 1995; 103(suppl):97-102.

 

PARTICULATE MATTER AND RESPIRATORY DISEASE

The ability of ambient airborne fine particulate matter to cause respiratory disorders, particularly among children, has been demonstrated in several European and American studies. However, a new German investigation is one of the first to document that respiratory symptoms improve as particulate matter concentrations decline.[1] The study data was based on analyses of two groups of schoolchildren living in the East German counties of Zerbst, Hettstedt, and Bitterfeld. There were 2,335 children in the first group and 2,536 children in the second group. The children, who were 5 to 14 years of age, were examined for bronchitis, colds, and other non-asthma-related respiratory diseases. The assessments occurred between 1992 and 1993 in the first group and between 1995 and 1996 in the second group. These were ideal times for the study because the air quality in East Germany was rapidly improving due to a widespread switch from coal to natural gas following the 1990 reunification of East and West Germany. The mean annual concentrations of total suspended particulates in the three counties fell from 65, 48, and 44 µg/m3 in 1993 to 43, 39, and 36 µg/m3 in 1995. During that time, bronchitis prevalence rates declined markedly in all three counties. Furthermore, during the second assessment period, the researchers found smaller, but still significant, reductions in the risk of otitis media (odds ratio [OR], 0.83; confidence interval [CI], 0.73 to 0.96), colds (OR, 0.74; CI, 0.64 to 0.86), and febrile infections (OR, 0.76; CI, 0.66 to 0.88). --Timothy Begany

Reference 1. Heinrich J, Hoelscher B, Wichmann HE. Decline of ambient air pollution and respiratory symptoms in children. Am J Respir Crit Care Med. 2000;161:1930-1936.