Air pollution

What is air pollution? Air pollution is the presence of substances in the air that are harmful to health or the environment. It can be easy to spot air pollution in cities but its effects are not limited to urban areas because air circulates freely all over the world. Air pollution can cause the destruction of forests, death of fish in lakes and premature death in humans. How does air pollution cause so many problems?

What causes air pollution? The most common pollutants found in air are: How are these molecules produced and how do they affect the environment? carbon dioxide (CO 2 ) sulphur dioxide (SO 2 ) carbon particulates nitrogen monoxide (NO) carbon monoxide (CO) nitrogen dioxide (NO 2 )

Causes and effects of air pollutants

How is carbon dioxide produced? The element carbon is found in all living things and moves through the environment in a chain of reactions known as the carbon cycle. In this cycle, the chemical reactions that take place during respiration and burning fossil fuels produce carbon dioxide. Carbon dioxide is an important atmospheric gas as it prevents heat radiation produced by the Earth from escaping into space. This is the greenhouse effect which makes the Earth warm enough for life. However, increased levels of carbon dioxide in the atmosphere could cause dramatic changes to the Earth’s climate.

How do fossil fuels cause air pollution? When fossil fuels are burnt fully in oxygen, the chemical reaction that occurs is called complete combustion. carbon dioxide fossil fuels oxygenwater++  The problems with burning fossil fuels include: Increased carbon dioxide levels due to human activities are thought to be connected to global warming. Increased carbon dioxide levels due to human activities are thought to be connected to global warming. Combustion also produces carbon particulate matter. Combustion also produces carbon particulate matter. Fossil fuels often contain sulphur and so the pollutant sulphur dioxide can be produced during combustion. Fossil fuels often contain sulphur and so the pollutant sulphur dioxide can be produced during combustion.

What is incomplete combustion? If there is not enough oxygen present when fossil fuels are burned, incomplete combustion occurs. This reaction produces carbon and carbon monoxide gas. Carbon monoxide gas is extremely harmful to human health because it stops blood from carrying oxygen.  Faulty gas appliances such as heating boilers, can produce carbon monoxide. This gas is colourless and odourless so boilers need to be checked for safety at least once a year.  Burning wood can also produce carbon monoxide. In areas where forests have been cleared and burned, carbon monoxide levels can reach dangerously high levels.

What is acid rain? Acid rain is rain or precipitation with a pH 5.6 or lower. It is caused by the pollutants sulphur dioxide and nitric oxides. The term ‘acid rain’ was first used by the Scottish scientist, Robert Angus Smith in the 19 th Century. He conducted air quality research in Manchester, one of the first industrialised cities in the world. Acid rain causes millions of pounds worth of damage to buildings in the UK each year. It is also harmful to the environment and can destroy forest habitats.

Causes and effects of acid rain

How does air pollution affect health? Weather reports often include warnings about high air pollution levels. Why is this? low moderate high Normally, pollution levels in the UK are not high enough to cause problems to people’s health. However, high pollution levels have been shown to irritate existing heart and respiratory problems. Air pollution can even cause premature death in the vulnerable or elderly. People who know they are sensitive to pollutants are advised to take precautions when air pollution levels are high such as not to exercise outside.

What is smog? Smog is a mixture of air pollutants and particulates that is sometimes found in the lower levels of the atmosphere. It can reach dangerous levels in built-up areas. Smog is more common in summer because hot weather acts as a catalyst in the formation of smog components. A large part of smog is ground level ozone (O 3 ). This is a highly toxic gas that can damage the lungs. Ozone is formed when nitrogen oxides and volatile organic compounds combine with oxygen.

Does air pollution cause asthma? Asthma is a chronic respiratory condition that affects the airways and can cause shortness of breath and wheezing. The UK has one of the highest rates of asthma in the world: more than one million people aged under 16 have asthma and in 2004, 1389 people died of asthma. Air pollutants can make asthma worse in people who already have the condition by triggering asthma attacks. However, currently there is not enough evidence to support the theory that air pollution causes people to have asthma. Often, asthma is an hereditary condition.

Why should we control pollution? Human actions can cause or reduce air pollution which is not just a current problem. For example, severe smog in London caused the premature death of people in Most of the smog was formed by high levels of particulates in the air caused by burning wood and coal for heating. The Clean Air Act of 1956 created smoke-free zones in cities. Power plants were moved to rural areas, reducing city smog. How else have human actions improved the atmosphere?

How can air pollution be reduced? Today, the combustion of fossil fuels is a major source of air pollution and so controlling their use is important in reducing pollution. This can be done in three key ways: Reduce the amount of fossil fuels used by taking simple steps such as changing to energy efficient light bulbs or cycling instead of using a car. Reduce the amount of fossil fuels used by taking simple steps such as changing to energy efficient light bulbs or cycling instead of using a car. Increase the efficiency of motor vehicle engines and power plants so that less fossil fuels are required. Increase the efficiency of motor vehicle engines and power plants so that less fossil fuels are required. Use chemical reactions to remove the most harmful pollutants from motor vehicle and power plant emissions. Use chemical reactions to remove the most harmful pollutants from motor vehicle and power plant emissions.

How can coal be made cleaner? Sulphur dioxide emissions from coal can be reduced in two ways: by removing sulphur from the coal before combustion or by filtering the emissions produced by combustion. A process called flue gas desulphurisation is used to filter emissions. Sulphur dioxide in the flue gas is removed by reacting it with limestone and water. This forms calcium sulphate, also known as gypsum which can be used in construction. limestone and water processed flue gas flue gas gypsum

How can vehicle pollution be reduced? A catalytic converter is a device that is fitted to the exhaust pipe of a car to clean up exhaust fumes. The inside of the converter has a honeycomb structure, covered in a metal catalyst, such as platinum or palladium. This structure maximises contact between the exhaust fumes and the metal catalyst to change the pollutants from combustion into less harmful substances. +oxygen carbon dioxide carbonmonoxide nitric oxides nitrogenoxygen+   +