Causes of air pollution

The activities of man has led to the decline in the quality of air around us. Man's activities release several substances or pollutants to the air, with dire consequences to health and safety of humans, animals and plants. Air pollution is responsible for adverse environmental effects such as acid rain, smog and greenhouse gases.

Some of the causes (or the sources) of air pollution are briefly discussed below:

Exhaust gases from vehicles and airplane engines

One of the major causes of air pollution is exhaust from engines of vehicles and planes. Vehicles and planes are operated by burning fossil fuels such as gasoline (or petrol), diesel, natural gas, fuel oil, jet fuels. These fossil fuels generate exhaust gasses that are discharged to the environment through the "exhaust pipes" of the vehicles/planes. The exhausts contain several substances such as

• Water vapour (H2 O);
• Nitrogen (N2);
• Carbon dioxide (CO2);
• Some hydrocarbons from un-burnt fossil fuels (CxHy);
• Carbon monoxide (CO) from incomplete fuel combustion;
• Nitrous oxide (NOx);
• Ozone (O3); and
• Some tiny solid particles (particulates) or soot.

These substances create smog as seen in major cities of the world. Smog causes respiratory problems in humans and animals and contribute to holes in the ozone layer, increasing the exposure to the sun's harmful rays. Smog also causes to visibility degradation and acid rain. CO2 is believed to be the major of the several greenhouse gases responsible for climate change and the global warming of the earth.

Exhausts from factory and home equipment engines

Similar to vehicles and airplanes, the engines of manufacturing factories and some home equipment are run by burning fossil fuels (wood, coal, shale gas, fuel oil, gasoline/petrol, etc). Manufacturing factory engines, power generation stations, refineries, mining operation equipment, as they are operated, release tremendous amount noxious, toxic and climate changing substances to the atmosphere.

Dust and related substances from industrial operations

Certain mills (e.g. iron mills, steel mills and paper mills) and plants (e.g. chemical plants, cement plants and asphalt plants), release dusts and other operation related emissions into the air.

Insecticides, herbicides and pesticides

These substances provide us relief from insects, weeds/herbs and pests. However, they have the side effects of releasing some dangerous substances to the atmosphere. When these substances are sprayed on the intended targets (pests, insects and weeds), some of the substances escape into the air and pollute the air. Large scale fumigation with helicoper is a good example of the release of the substances to the air.

Radioactive (nuclear) fallout

Radioactive fallout refers to the residual radioactive material (dusts and ashes) "dispersed" into the atmosphere following a nuclear blast or reaction conducted in an unshielded facility. It can result when a nuclear weapon explodes or from a damaged nuclear plant. Nuclear fallout materials are very dangerous to human health and compromise the integrity of the environment to which they are released.

Fertilizer dust

Dusts from fertilizers applied to farm crops and other plants to assist their growth cause the pollution of the atmosphere.

Indoor air pollution

In the developing countries and poor communities of the developed world, cooking and heating with wood and other solid biofuels, using open fire/3-stone stove or some other conventional stoves, generate tremendous smoke that pollute the surrounding air. Smoke consists of small particles and carbon dioxide from incomplete combustion.

In homes in developed world and developing worlds alike, where there are no effective cross-ventilation smokes, fumes from newly installed carpets, newly painted surfaces, and fumes from cleaning substances cause air pollution.

Natural causes

There are also the natural causes of air pollution. These include forest fires, volcanic eruptions, wind erosion, pollen dispersal, evaporation of organic compounds, and natural radioactivity among others. Natural air pollution occur only in few locations in the world, but their effect could be felt in several parts of the world. For instance, volcanic eruption can eject tons of volcanic ash which could lead to ash clouds that could affect worldwide travels. An example in recent past are the 2010 eruptions of Eyjafjallajökul in Iceland. The eruptions caused caused eserious disruptions to air travel across western and northern Europe over an initial period of six days in April 2010. Localised eruptions continued to occur until October 2010 when the eruption was declared over as snow no longer melt as it falls. 

The theme of World Environment Day - June 5 2019 is Air Pollution. You can see the same information at China to host 2019 World Environment Day.