Sar hs 396 part of the problem increasing transportation. Air pollutants: airbore particles or gasses that occur in concentrations that endanger the health and well-being of organisms or disrupt the orderly functioning of the environment. Primary pollutants: emitted directly from an identifiable source. Secondary pollutants: produced in the atmosphere when certain chemical reactions take place among primary pollutants. Natural: biogenic (volatile organic compounds from vegetation, pollens, volcanic gases, dust from deserts. Anthropogenic (leaded fuel, sulfur dioxide from power plants, carbon monoxide from motor vehicles, nitrogen oxide from electric utilities) Weather influences dilution and dispersal of air pollutants. Air pollutants effect the weather and climate. Air is never clean (always have natural air pollution: ash, salt particles, pollen and spores, smoke, and windblown dust. Major sources: emitting more then 10 tons/year (26%) Area sources: less than 10 tons/year (24%) Criteria pollutants (6 major ones: key outdoor air pollutants defined by the clean air act.