لخّصلي

AIR POLLUTION

Air pollution is the introduction of chemicals, particulates, biological materials. Or other harmful materials into the earth's atmosphere.
There two sources of air pollution:
1.Natural sources of air pollution:
Volcanoes spew out ash, acid mist, hydrogen sulfide, sea spray and decaying vegetation are the major sources of reactive sulfur compounds in the air.
Storms in arid regions raised dust clouds that transport millions of tons of soil.
Bacterial metabolism of decaying vegetation in swamps at cellulose in the gut at termites and ruminate animals is responsible for about two-third of the methane in the air.
2.Human-caused (anthropogenic) air pollution).
According to their source palpitates categorized to:
Primary pollutants: are those released directly from the source into the air in a harmful form.
Secondary pollutants: are modified to a hazardous from other they enter the air or are formed by chemical reaction as components of the air mix and interact. Photochemical oxidants and atmospheric acids formed by these chemical.
Fugitive emissions: are those that do not go through a smokestack like dust from soil erosion, rock crashing and building construction and destruction.
According to their content pollutant categorized to:
(USA Clean Air Act of 1970 designated 7 major pollutants:
Co2, NO, particulate, photochemical oxidants, lead and hydrocarbons.
1.Sulfur Compounds:
Natural sources of sulfur: volcanoes, oceans, fossil fuel biomass burning. Total annually emissions of sulfur from all amount to some 114 million metric tons, anthropogenic sources represent about two third of the total sulfur flux.
2.Nitrogen Compounds:
Source: soil microbes, fossil biomass burning, nitrogen oxides combine with water to make nitric acid, yearly 230 million metric tons, anthropogenic about 60%.
3.Carbon component: CO and CO2
Source CO2: respiration, fossil fuels burning, land clarity, about 7-8 billion tones by fossil fuels combustion and 1-2 billion by forest and grass fires.
Source CO: incomplete combustion of fossil fuels, incineration of biomass or solid waste.
One billion metric tons yearly, half of that is human activities, 90% of CO in the air is consumed in photochemical reactions that produce ozone.

4.Particulates:
Sources: dust, ash, soot. Lint, smoke and many other suspended materials. Anthropogenic amount about 362 million tons of materials per year.
5.Metals and halogens: about 2 million
Effects of air pollution. WHO estimate that 2 million of children and 5 to 6 million people die every year from illness related to air pollution, heart attack, respiratory diseases and lung cancer.
How does pollution harm us? Some gases such as SO2, N act as irritant that damage tissues in the eyes and respiratory passage. CO binds to hemoglobin and decreases the ability of red blood cells to early oxygen.