ABSTRACT
Visual ranges in the national parks have been substantially reduced by air pollution. Haze is caused when sunlight encounters tiny particles in the air, some of the lights will be absorbed or scattered. The majority of these particles originated from anthropogenic sources. Odor is a property of a substance that simulates the olfactory organ. Odors from a single compound can be regulated in a manner similar to a criteria pollutant. Lead is one of the six criteria pollutants. Level of lead in the ambient air has decreased by 99% between 1980 and 2016 as a result of regulatory efforts including the removal of lead from gasoline for motor vehicles. However, sources of lead emissions exist. Although there are numerous indoor air pollutants that may be present in a building, they typically fall into three basic categories: biological, chemical, and non-biological particle.
