Sources of air pollution
Sources of air pollution can be split into 2 main categories; those produced through human-activity (anthropogenic) and those produced naturally.
Pollutants can be Primary pollutants that are emitted directly to the atmosphere from a source and Secondary pollutants that are not directly emitted into the atmosphere but are formed as a result of chemical reactions from primary pollutants.
The weather plays an important role in moving pollutants from the source to other locations.
- Energy generation - Fossil fuels are fuels produced in the earth from the decomposition of living things under pressure. They all contain carbon and other elements such as nitrogen, sulphur, oxygen and hydrogen. The burning of fuels is one of the main sources of air pollution in the UK. Fossil fuels are burnt in power station to produce electricity. The Kingsnorth Power Station in Kent was closed in 2013 as it did not meet improved emission requirements! Fossil fueled power stations cause emissions of NO2 and PM10, PM2.5 and SO2 from non-gaseous fuels. Power generation is also is a dominant source of CO2 emission in the UK thought to be the major cause of climate change.
- Transport - Vehicles emit particles (PM10 and PM2.5) and gases (e.g. NO2) through the exhaust from burning petrol, diesel etc... The effect of vehicle emissions are most noticeable in cities and towns where congestion is likely and volumes of traffic are high. Pollutants caused by transport can be primary or secondary and currently there is a lot of interest in NO2 emissions from transport (cars, lorries, buses, planes, trains and shipping etc…). The level of pollution cause by different vehicles depend on the vehicle type, journey type and fuel. The Emission Calculator provides information on vehicle emissions. Pollution from transport is thought to have caused concentrations of air pollutants to exceed limits set by the European Union (EU) limits in some urban locations in the Kent and Medway area. Walking, cycling or using public transport can help reduce congestion and hence emissions from transport.
- Industry - Industrial processes, such as iron and steel refineries, release large amounts of various pollutants in the form of gases (e.g. NO2, SO2 and CO) and particles (PM10 and PM2.5) into the atmosphere. Legislation can and has been introduced to try to cut down on avoidable pollution by various industries to attempt to prevent unnecessary emissions.
- Agriculture - There is plenty of farming in Kent, so this may well be a potential source of pollution. Agriculture can produce pollutants such as NO2, particulate (PM10 and PM2.5) and SO2 from combustion activities. It is also common for fertilisers to be used in farming. Man-made fertiliser usually contain ammonia. there can be potential for fertilisers to run off into river, streams and lakes which can lead to a reduction in oxygen in the water, this may cause death to aquatic animals!
Livestock like cows and sheep release a huge amount of methane through belching and breaking wind! Methane is a colourless gas which is produced in their stomachs when bacteria break down the food they eat. Methane is the second most important greenhouse gas after carbon dioxide, which means that it also contributes towards climate change.
- Other man-made sources of air pollution include waste incineration, dust from building sites, controlled burning, gas from aerosols, fireworks, and more!
- Waste - In the UK, waste disposal is the largest emitter of methane gas (CH4), with agriculture and livestock coming second. Methane is released into the atmosphere when waste decomposes.
- Emissions from Continental Europe - Pollutants that are emitted from Europe can be blown to the UK and effect the quality of the air we breath- Europe exporting pollution to the UK is an unwanted import!!!
- Sand and dust - In particular from the Sahara desert, which can be carried long distances and deposited throughout Europe, even reaching the UK.
- Sea salt - Can be carried in the air as sea-spray; perhaps you've noticed this near the coast in Kent?
- Volcanoes - Volcanoes can emit high concentrations of particulate and SO2 into the atmosphere.
- Forest fires - Release gases and particles into the atmosphere. Geology suggests that 55 million years ago Scalers Hill near Cobham in Kent underwent a series of regular and severe wild fires! 'Wild' or out of control fires still occur in Kent, although they are usually started accidentally or deliberately by humans such as the fire that occurred at Medway City Estate where fire broke out at a Plastics recycling facility and at a pallet recycling facility in Faversham, which both occurred in June 2015.