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Contents
What is air?
Air pollution
Primary and secondary pollutants
Main primary pollutants:
Carbon monoxide (CO)
Sulphur oxides (SOx)
Nitrogen oxides (NOx)
Particulates (PM)
Secondary pollutants:
Ground level ozone
Acid rain
Nutrient enrichment
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Volcanoes Wildfires Primary pollutants Carbon monoxide CO Carbon dioxide CO2 Sulphur dioxide SO2 Nitric oxide NO Nitrogen dioxide NO2 Hydrogen peroxide H2O2 Secondary pollutants Sulphur trioxide SO3 Nitric acid HNO3 Sulphuric acid H2SO4 Ozone O3 Volatile organic compounds VOCs Particulates (PM) Ammonia NH3 Particulates (PM) Power generation Vehicle exhausts Aeroplanes Factories Agriculture Air pollutants can be classified as: Ammonium NH4+ A primary pollutant is one that is emitted directly from a source. Secondary pollutants are formed when primary pollutants interact with each other in the atmosphere. The main primary pollutants are CO Carbon monoxide Carbon monoxide (CO) is a colourless, odourless, and very poisonous gas. It is formed as a by-product of incomplete combustion processes involving carbon based energy sources, such as the burning of petrol, coal or wood. During the process, if there is not enough oxygen available to create carbon dioxide as a by-product, then carbon monoxide is created instead. Carbon monoxide is dangerous to humans, once inhaled it competes with oxygen by attaching on to haemoglobin in red blood cells and starving vital organs such as the brain, nervous system tissues and the heart of oxygen, reducing their ability to work properly. The biggest sources of carbon monoxide comes from vehicles, especially when they are moving slowly or when the engine is idle. PM Particulates Particulates or particulate matter (PM) are tiny pieces of solid matter or liquids in the air, and can consist of hundreds of different chemicals, including carbon, sulphur, nitrogen and metal compounds. They originate from many different sources, including construction sites, vehicle exhausts, industrial sites, unpaved roads, and come in many shapes and sizes. Some are large enough to be seen with the naked eye, whereas others can only be seen through powerful microscopes. Larger particles (larger than 10 micrometers) are generally filtered out of the body via the nose and throat. Particles that are 10 micrometers or smaller can be inhaled into the deepest parts of the lungs. Fine particles are smaller than 2.5 micrometers and are small enough to pass from the lungs into the blood supply. PM2.5 particles <2.5 µm each Human hair 50 µm Finest beach sand 90 µm PM10 particles <10 µm each NH3 Ammonia (NH3) is a very soluble colourless gas with a strong pungent smell. It is primarily released from animal waste and fertiliser use, vehicle exhaust and other processes. This forms secondary pollutants with the acid pollutant of SO2 and NOx to produce ammonium (NH4+). These can then be move by the air over large distances from the initial source. The biggest source of ammonia release is from agriculture including the intensive rearing of animals and crops. When ammonia and the ammonium pollutants fall to the ground, they add to the nitrogen enrichment effects, increasing the growth of some plants, including trees. Ammonia Secondary pollutants
