Air Pollution

Abstract

Air pollution is the presence of any substance in the atmosphere at a concentration high enough to produce an objectionable effect on humans, animals, vegetation, or materials, or to significantly alter the natural balance of any ecosystem. Substances can be solids, liquids, or gases, and can be produced by anthropogenic activities or natural sources. In this article only nonbiological material is considered and the discussion of airborne radioactive contaminants is limited to radon. The original six criteria pollutants, for which the Environmental Protection Agency is required to summarize published information on each, were sulfur dioxide, SO 2 ; carbon monoxide, CO; nitrogen dioxide, NO 2 ; ozone, O 3 ; suspended particulates; and nonmethane hydrocarbons, NMHC. The NMHC are now referred to as volatile organic compounds (VOC). The NMHC were dropped from the list shortly after the criteria pollutants were so designated. In the late 1970s, lead, Pb, was added to the list and in 1987, so was particulate matter having an aerodynamic diameter of less than or equal to 10 µm, PM 10 . There have been several developments since the establishment of the criteria pollutants. In the mid‐1970s it was shown that high concentrations of O 3 and sulfate haze could be transported hundreds of miles, and acid deposition studies in the 1980s clearly illustrated the international and global aspects of this transport. Then stratospheric O 3 depletion and global warming became issues and air pollution was finally viewed in a global context. Air pollution can be considered to have three components: sources, transport and transformations in the atmosphere, and receptors. The source emits airborne substances. The receptor is the person, animal, plant, material, or ecosystem affected by the emissions. In the United States, the framework for air quality management is the Clean Air Act (CAA), which defines two categories of pollutants; criteria and hazardous. For the criteria pollutants, the CAA requires that EPA establish National Ambient Air Quality Standards (NAAQS) and emissions standards for stationary sources and for motor vehicles. For the hazardous air pollutants, only emissions standards for some sources are required, but the number is growing rapidly. Current air pollution concerns include photochemical smog, volatile organic compounds (VOC), nitrogen oxides (NO x ), sulfur oxides (SO x ), carbon monoxide (CO), particulate matter, global warming (the greenhouse effect), and stratospheric O 3 depletion, among others.

A Reappraisal of Various Compacting Processes for Wasted Expandable Polystyrene (EPS) Foam

“…This pentane entrapped in EPS foam, industrially applied as physical blowing agents for the preparation of EPS, have major disadvantages that are harmful to the environment. VOCs such as pentane are precursors for a multitude of other photochemical smog that also have significant environmental consequences [4]. Heat cycle applied to the process of compaction also leads to the degradation of the polymeric properties of PS and the quality of the recycled products is lowered.…”

Water-Expandable Polystyrene Using Cross-Linked Starch Nanoparticle as Water-Stabilizing Agent

“…The route starts with the reaction of styrene monomer dispersed in a water medium containing suitable suspension agents and an organic blowing agent such as pentane. To avoid the use of a flammable blowing agents and its harmful environmental effects, , the concept of water-expandable polystyrene (WEPS) was proposed by Crevecoeur et al in which the organic blowing agent is replaced by water. However, because of the complete immiscibility of water and polystyrene (PS), encapsulating enough water in polystyrene beads is still a challenge.…”

Artificial neural network with backpropagation learning to predict mean monthly total ozone in Arosa, Switzerland

“…warm, sunny/clear day) ultraviolet radiation (UV) causes the precursors to interact photochemically in a set of reactions that result in the formation of ozone [3,4]. The process of ozone formation can be expressed as [19]:…”

“…It is responsible for crop damage, and is suspected of being a contributor to forest decline in Europe and parts of United States [19]. Studies revealed that since the end of 50s tropospheric ozone increased in the northern hemisphere [8].…”

“…Studies revealed that since the end of 50s tropospheric ozone increased in the northern hemisphere [8]. This increase is contributed by intrusion of ozone rich stratospheric air, ozone production from methane oxidation, the photooxidation of naturally emitted VOCs from vegetation, and the long-range transport of ozone formed from the photooxydation of anthropogenic VOCs and NO X emissions [19].…”