Air pollution is the introduction of chemicals, particulate matter,or biological materials that cause harm or discomfort to humans or otherliving organisms, or cause damage to the natural environment or builtenvironment, into the atmosphere.The atmosphere is a complex dynamic natural gaseous system that isessential to support life on planet Earth. Stratospheric ozone depletiondue to air pollution has long been recognized as a threat to humanhealth as well as to the Earths ecosystems.
A substance in the air that cancause harm to humans and theenvironment is known as an airpollutant. Pollutants can be in theform of solid particles, liquiddroplets, or gases. In addition, theymay be natural or man-made.
Pollutants can be classified as primary orsecondary. Usually, primary pollutants aredirectly emitted from a process, such as ashfrom a volcanic eruption, the carbonmonoxide gas from a motor vehicle exhaust orsulfur dioxide released from factories. Secondarypollutants are not emitted directly. Rather, theyform in the air when primary pollutants react orinteract.
Sulphur oxides Nitrogen oxides Carbon monoxideIt is produced by They are emitted from It is a colorless, odorless,volcanoes and in high temperature non-irritating but veryvarious industrial combustion, and are poisonous gas. It is a productprocesses. also produced naturally by incomplete combustion of during thunderstorms fuel such as natural gas, coal by electrical discharge. or wood. Vehicular exhaust is a major source of carbon monoxide.
Air pollution is a significant risk factor for multiple healthconditions including respiratory infections, heart disease,and lung cancer. The health effects caused by air pollutionmay include difficulty in breathing, wheezing, coughing andaggravation of existing respiratory and cardiac conditions.These effects can result in increased medication use,increased doctor or emergency room visits, more hospitaladmissions and premature death.
The World Health Organization states that 2.4 million people die each yearfrom causes directly attributable to air pollution, with 1.5 million of thesedeaths attributable to indoor air pollution." A study by the University of Birmingham has shown a strong correlationbetween pneumonia related deaths and air pollution from motorvehicles. Publication in 2005 suggests that 310,000 Europeans die from airpollution annually.
Cities around the world with high exposure to airpollutants have the possibility of children livingwithin them to develop asthma, pneumonia andother lower respiratory infections as well as a lowinitial birth rate. Protective measures to ensurethe youths health are being taken in cities suchas New Delhi, India where buses nowuse compressed natural gas to help eliminate the“pea-soup” smog.
Efforts to reduce pollution from mobilesources includes primary regulation,expanding regulation to new sources,increased fuel efficiency (such asthrough the use of hybrid vehicles),conversion to cleaner fuels (suchas bioethanol, biodiesel, or conversionto electric vehicles).
The following items are commonly used as pollution controldevices by industry or transportation devices. They can eitherdestroy contaminants or remove them from an exhaust streambefore it is emitted into the atmosphere.
ScrubbersBaffle spray scrubberCyclonic spray scrubberEjector venturi scrubberNOx controlLow NOx burnersNOx scrubbersExhaust gas recirculationCatalytic converter (also for VOC control)Adsorption systems, such as activated carbonFlaresThermal oxidizersBiofiltersAbsorption (scrubbing)Vapor recovery systemsSorbent Injection TechnologyElectro-Catalytic Oxidation (ECO)K-Fuel