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.