Many people use wood stoves and fireplaces to heat their homes．Scientists have become worried about the smoke that they give off．Harmful chemicals are in the smoke．The smoke is causing air pollution．The pieces of pollution,called soot,are floating in the air．They are too tiny to see．Scientists must use a microscope to see them.
Small amounts of soot are safe,but large amounts can be dangerous．The govenment wants to limit this kind of pollution．It may stop people from using their fireplaces.
The air is tested every day．When soot levels are high,more than 65 micrograms of soot per cubic meter,factories must stop making smoke．The government thinks that limit should be much lower.
Factories produce the most smoke and soot．But the government thinks that all types of burning should be limited．The soot levels from factories and homes could be limited．Home owners may have to install new wood stoves that they comply with the new law．Or,they may not be able to bum on days when the air quality is bad.
Residents of some towns are fined if they violate the burning ban．Scientists hope these new regulations will make the air cleaner and less harmful to breathe.
What could home owners do to comply with the new regulation?
第二、三、四段。政府认为应当限制煤烟的排放量，以减少空气中的污染颗粒。工厂是排放煤烟最多的地方，应当加以限制。但政府认为，住宅也应受此限制，减少煤烟的排放。新的法律规定住宅必须安装新型的低烟壁炉，否则，在污染比较严重的时期，这些住户是不能使用他们的壁炉的。
