Daily variation in air quality.

We related year-round air pollutant concentration in three small U.S. towns, with considerable differences in population density and industrial activity, to air temperature, wind direction, wind speed, rainfall, sky conditions, and days of the week (workdays vs. pended particulates) concentrations can be explained by changes in weather conditions. During weekends, pollution did not decrease consistently and, in some instances, may have increased as a result of dense recreational traffic. We suggest that recognition of the multifactorial causation of high levels of air pollution may lead to more realistic, more effective, and less costly air pollution ocntrol programs.