Benzene is a colourless, flammable, toxic liquid with a "pleasant" odour. In the atmosphere it can come from vehicles or evaporation in petrol. Levels are therefore highest close to busy roads or in the vicinity of petrol filling stations. Benzene can also be released to the air from tobacco smoke, glues, paints, furniture wax, and detergents.
Butadiene is similar to Benzene. It is in the family of "volatile Organic" Compounds. It is colourless, odourless and easily changes to a gas at room temperature. They are called organic because they contain the element carbon in their molecular structures. Sources of butane include the manufacturing of rubbers, petrol driven vehicles and cigarette smoke. Butadiene and other Volatile Organic Compounds are a concern because long term exposure to high levels of benzene is known to cause cancer, as well as other health problems. Other effects can include skin and eye irritation and breathing problems.
Carbon Monoxide is a gas that comes from burning of fossil fuels. It cannot be smelt and is colourless. Carbon Monoxide is released when engines burn fossil fuels. Emissions are higher when engines are not tuned properly, and when fuel is not completely burned. Cars emit a lot of the carbon monoxide found outdoors.
Lead is a grey metal that is very toxic and is found in a number of forms and locations. Outside lead comes from cars in areas where unleaded petrol is not used. Lead can also come from power plants and other industrial sources. In the UK we have stopped using unleaded petrol. Inside, lead paint is an important source of lead, especially in houses where paint is peeling. Lead in old pipes can also be a source of lead in drinking water. High amounts of lead can be dangerous for small children and can lead to lower IQs and kidney problems. For adults, exposure to lead can increase the chance of having heart attacks or strokes.
Nitrogen Dioxide is a reddish-brown gas that comes from the burning of fossil fuels. It has a strong smell at high levels. Nitrogen dioxide mostly comes from power plants and cars. It is formed when nitrogen in the fuel is burned and also when nitrogen in the air reacts with oxygen at very high temperatures. Nitrogen Dioxide can react in the atmosphere to form ozone, acid rain, and particles. High levels of exposure to Nitrogen Dioxide can give people coughs and can make them feel short of breath. People who are exposed to nitrogen dioxide for a longer time have a higher chance of getting respiratory infections. Acid rain can hurt plants and animals and can make lakes dangerous to swim or fish in.
Ozone is a gas that can be found in two places. Near to the ground (the troposphere), it is a major part of smog. higher in the air (the stratosphere), it helps block radiation from the sun. Ozone is not created directly, but is formed when nitrogen oxides and volatile compounds mix in the sunlight. That is why ozone is mostly found in the summer. nitrogen Dioxides come from cars and burning coal, or other fossil fuels. there are many types of volatile organic compounds, and they come from sources ranging from factories to trees. Ozone near the ground can cause a number of health problems. It can lead to more frequent asthma attacks in people who have asthma, and can cause sore throats, coughs, and breathing difficulty. It may even lead to premature death. Ozone can also hurt plants and crops.
Particulate is solid matter that is suspended in the air. To remain in the air, particles are usually less than 0.1mm wide and can be as small as 0.00005mm (very small). Particle matter can be divided into two types - course particles and fine particles. course particles are bigger than 0.002mm and are formed from sources like road dust, sea spray, and construction. Fine particles are smaller than 0.002mm and are formed when fuel is burned in automobiles and power plants. particle matter that is small enough can enter the lungs and cause health problems. Some of these problems include more frequent asthma attacks, respiratory problems, and premature death. Particle matter can also make clothes and other materials dirty.
Smoke is produced when fuels are burnt to generate heat and electricity.
Sulphur Dioxide comes mostly from the burning of coal or oil in power plants. It also comes from factories that make chemicals, paper, or fuel. Exposure to sulphur dioxide can affect people who have asthma or emphysema by making it more difficult for them to breathe. It can irritate people' eyes, noses and throats. It can harm trees, crops, and damage buildings