Comparing the levels of pollution in different urban locales
Areas that see a high levels of activity and traffic such asthe marketplace, the bus station and hospitals have a higher pollution level than areas that have low levels of traffic.
When air is polluted, it means that there are many unwanted particles and substances in the air. These are called pollutants. Some common sources of pollutants are: construction sites, heavy automobile traffic, agriculture, power generation plants and factories. Although some pollutants do not directly affect us, they can react with other substances in the air and become harmful.
Air pollutants exist in the form of gasses and particles. These are common gas pollutants: carbon monoxide, nitrogen dioxide, sulfur dioxide, methane gas, ammonia and volatile organic compounds. Most air pollutants are released by the process of fuel combustion that occurs in the engines of cars, trucks and other vehicles, including airplanes.
In the last decade, there has been an alarming rate of increase in air pollution, and this constitutes a serious threat to public health and to the environment. Air pollution can cause people to suffer from various ailments such as breathing difficulties and frequent asthma attacks. The environment has also been very adversely affected by problems such as ozone layer depletion, higher levels of acid rain and ocean acidification, and global warming.