car exhaust.

Car exhaust is a big problem is densely populated areas. The more people there are, the more cars there are. The more cars there are, the more exhaust that builds up in our atmosphere. Cars have two opposite personalities. One is friendly and attractive the other is destructive and can be lethal. Driving a car is the most polluting act an average citizen commits. Emissions from passenger vehicles are increasing in Canada and the US despite attempts to make engines more fuel efficient and despite the addition of antipollution devices. The two main reasons are: 1. vehicle use has increased; 2. cars are getting bigger and pick-up trucks, vans and sports vehicles are often replacing smaller, lighter passenger cars. The average new vehicle in 2003 consumed more fuel that its counterpart in 1988. In the USA in 1987 cars averaged 25.9 miles to the gallon. Fuel efficiency dropped to 24.6 miles/gallon by 1998 and is dropping further as more larger vehicles replace smaller ones. Despite scientific evidence of climate change, governments in most affluent countries have avoided their responsibility to reduce emissions of greenhouse gases. The USA is the biggest emitter of greenhouse gases worldwide.

Sewage.

Sewage is a big contributer to pollution. Sewage is mainly a liquid waste containing some solids produced by humans which typically consists of washing water, faeces, urine, laundry waste and other material which goes down drains and toilets from households and industry. Sewage services exist to manage sewage by collection, treatment and recycling or safe disposal into the enviornment. Sewage pipes, or sewers, collect sewage and take it for collection or disposal. Sewage dumped into a river can flow into the ocean and it kills tons of sea creatures every year. Sewage treatment is the process of removing the contaminants from sewage to produce liquid and solid suitable for discharge to the environment or for reuse.

Pollution.

Pollution has gotten worse over the years. If you look up pollution in the dictionary, you will find the addition of any substance or form of energy (e.g., heat, sound, radioactivity) to the environment at a rate faster than the environment can accommodate it by dispersion, breakdown, recycling, or storage in some harmless form. Many things are considered pollution that you would not think to be. For example, carbon dioxide is found in all animal tissues, but in a concentrated form, it can also kill them. Pollution is the result of mankind congregating in one place and remaining there for a long time. Pollution was never a problem as long as there was enough space avaliable for every person or group of people. When ares start to get densely populated, various things began polluting the city or area they lived in. A big contributer to the pollution of heavily populated areas is car exhaust. A lot of people means a lot of cars, and every single one of those cars releases exhaust, which heavily pollutes the air. There are other types of pollution like sewage, cigarette smoke, and radioactivity.