Atmospheric contaminants: sources, chemical characterization and hazards.

Abstract

Abstract As per the World Health Organization (WHO) estimates, around 7 million people died in the year 2012 due to exposure to air pollution. This estimate suggests that one in eight of total global deaths are caused by exposure to air pollution. Thus, air pollution, along with its direct and indirect impacts, can be regarded as the biggest environmental health hazard. While the natural emissions of atmospheric contaminants/pollutants have remained relatively stable over the past century, the emission fluxes of air pollutants from various anthropogenic activities have now surpassed their natural discharge. Over the last century, increased combustion of fossil fuels for meeting growing energy demands and several other anthropogenic activities (such as farming, deforestation, mining, biomass burning and waste incineration) have led to a substantial rise in emissions of various atmospheric pollutants, resulting in a rapid change in the basic chemistry of the atmosphere. Evidence from numerous epidemiological studies suggests that the quality of air inhaled is directly linked to health. Escape of hazardous air contaminants, their dispersal in the atmosphere, and exposure are linked to various cardiovascular and respiratory diseases and cancer. Both long-term as well as short-term exposure to air pollution is hazardous to the nourishment and sustenance of life on Earth. Exposure to air pollution is largely prevalent and unavoidable in the contemporary world. Thus, reduction and eventual elimination of fossil fuel usage and a drive towards cleaner energy resources are some of the steps that are required to reduce atmospheric pollution, and to mitigate the associated health and environmental hazards. In addition, educating the population regarding deleterious direct and indirect impacts of air pollution, efficient application of adequate policies to limit air pollution, and sustainable efforts in constraining various sources of air pollution are some of the steps that are needed to be taken. Further, accidental release of harmful short-lived radionuclides (from e.g. the Chernobyl and Fukushima Daiichi nuclear power plants) and their transport in the atmosphere pose serious health and environmental hazards. The increase in the atmospheric concentration of pollutants (for example ozone and black carbon) has also been linked to adverse effects on crop production and yield, eventually putting more stress on food resources. Here, in the present chapter, we discuss various sources of air contaminants and their chemistry in the atmosphere. Further, various health and environmental hazards of air pollution have also been highlighted and discussed.