What is Air Pollution?
* Air pollution can be defined as the presence of any harmful material in the air and the atmosphere that can cause damage to human beings and other living organisms. * Air pollution could also be in the form of disturbances to the normal composition of the air such that there is an undesired effect on the environment or living things. * Under normal circumstances, the earth’s atmosphere consists of nitrogen (~78%), oxygen (~21%), small amounts of carbon dioxide (~0.03%) and other gases like water vapor and some tiny particles of liquid/solid matter like dust.
Natural Sources of Air Pollution
* Carbon dioxide and sulfur dioxide are the primary gases that are released during volcanic eruptions. * Other gases like hydrogen sulfide, hydrogen chloride, hydrogen fluoride, carbon monoxide, halocarbons and some metal chlorides are also released into the atmosphere. * Besides the volcanic gases, there is also volcanic ash. Volcanic ash can move hundreds to thousands of miles downwind from a volcano.
* All forest fires emit carbon monoxide, sulfur dioxide, nitrogen dioxide, ozone, and particulate matter.
* Acts by picking up loose particles of dirt and soil, mostly where plants are too sparse to hold the soil together.
* Nuclear elements like uranium are found inside the earth’s surface, and when these elements decompose they release a noble gas known as Radon into the atmosphere.
* Farm animals like cattle release methane into the atmosphere during the end stages of their digestive cycles. * Methane is also produced by the natural rotting of plants.
Factors Affecting Air Quality such as
Weather, Wind and Geography
* Turbulence mixes pollutants into the surrounding air.
* Wind speed also contributes to how quickly pollutants are carried away from their original source.
- Temperature inversions occur when a stable layer of warm air overlays cooler air, reversing the normal temperature decline with increasing height, and preventing convection currents from dispersing pollutants.
• Dust Domes and Heat Islands
- Sparse vegetation and large amounts of concrete and glass create warm,
stable air masses, heat islands, over large cities. Concentrates pollutants in a “dust dome”.
* An urban heat island (UHI) is a metropolitan area that is significantly warmer than its surrounding rural areas due to human activities.
* The dome-shaped formation of stagnant and polluted air above a city is known as a dust dome.
EFFECTS OF AIR POLLUTION
* A variety of pollutants have known or suspected harmful effects on human health and the environment.
* Exposure to air pollution is associated with numerous effects on human health. It can cause both acute (short-term) and chronic (long term) health effects.
* Acute effects- are usually immediate and often reversible when exposure to the pollutant ends. -->These include eye irritation, headaches, and nausea.
* Chronic effects- are usually not immediate and tend not to be reversible when exposure to the pollutant ends. These include decreased lung capacity and lung cancer resulting from long term exposure to toxic air pollutants.
Most common pollutants:
1. Carbon Monoxide
Description: colorless gas
Sources: motor vehicle exhaust, indoor sources include kerosene or wood
Health Effects: headaches, reduced mental alertness, heart attack,
cardiovascular diseases, death.
Welfare Effects: contribute to the formation of smog.
2. Sulfur Dioxide
Description: colorless gas that dissolves in water vapor to form acid, and
interact with other gases and particles in the air.
Sources: petroleum refineries, manufacture of sulfuric acid, coal-fired
Health Effects: eye...
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