Air Pollutants and their Effects on Plants and Human Health

摘要

Anthropogenic emission of harmful substances into theatmosphere is called air pollution. These pollutants modify thechemical composition of the natural atmosphere. Increase inthe concentration of greenhouse gases is also responsible forair pollution. Besides anthropogenic emissions, geogenic andbiogenic emissions also increases the risk of air pollution.Geogenic emission comes from the non-living world such asvolcanic emissions, sea-salt emissions, and natural fires,whereas biogenic emissions release from the living world;such as volatile organic compound (VOC) emissions fromforests and emission of methane from swamps. Humanactivity also influences geogenic and biogenic emissions. Useof nitrogen fertilizers (urea) in agriculture results in increasedbiogenic emissions. Therefore, we can conclude that pollutionis any substance which is emitted into the air from ananthropogenic, biogenic, or geogenic source. These substancesare not part of the natural atmosphere and their concentrationis more than the normal. They cause short-term or long-termnegative effects. Primary or secondary air pollutants consist ofgas and particle contaminants. These pollutants areresponsible for damaging our environment, as they have directas well as indirect negative impact on the environment, humanhealth, vegetation and our cultural heritage. It has beenreported that more than 3,000 substances that are not part ofthe atmospheric composition, emitted in the atmosphere canbe considered air pollutants [1]. These pollutants are usuallyemitted by industrial activities and by the transport sector andare transported in the air over long distances. The most famouskind of atmospheric pollution is the photochemical cloud,whose components are formed due to the complicatedchemical reactions in atmosphere. The principal reactants arethe hydrocarbons, nitrogen oxides, sulphur oxides, ozone andultraviolet radiation. All air pollutants do not have the samecapability for producing same toxic effects due to thedifference in their physical and chemical properties [2].