The air pollution study (AHSMOG Study) began in 1977 as a substudy of 6,338 individuals who also participated in the larger parent Adventist Health Study (AHS-1). AHS-1 had already enrolled over 34,000 non-smoking, non-Hispanic white adults in California; it was believed that this population provided a unique opportunity for investigating the health effects of long-term exposure to ambient air pollutants with very little distortion by active tobacco exposure.

However, Seventh-day Adventists' contact with ambient air pollution varies greatly by virtue of their choice of residence and occupation. This variability in pollution exposure makes possible the evaluation of the relationship between exposure and health effects with minimal distortion by tobacco smoke.

Participants were from these geographic areas:

  • South Coast air basin (Los Angeles and eastward)
  • San Diego metropolitan district
  • San Francisco metropolitan district
  • Random sample from the rest of California (13%)

These participants were invited to complete National Heart, Lung and Blood Institute respiratory symptoms questionnaires in 1977, 1987, 1992 and 2000. Throughout that time, they have been followed and monitored for the following outcomes:

  • Newly diagnosed malignant neoplasms
  • Coronary heart disease
  • All-cause mortality

In addition, computer algorithms were applied to the respiratory symptoms questions. This was done in order to classify individuals as having “none,” “possible” or “definite” symptoms for chronic bronchitis, asthma and emphysema.

Funding for acquisition of data for the AHSMOG study has come from: the National Cancer Institute; the National Heart, Lung and Blood Institute; the National Institute for Environmental Health Sciences; the U.S. Environmental Protection Agency; and the American Cancer Society.