—_____ 2001.

—I'm sure I've seen him _____, but I can't remember the right place.

When people talk about air pollution, they are usually thinking about outdoor air1. But do you know that there is also air pollution inside homes, offices, hotels and other buildings? The air in your home can be 2 to 100 times more polluted than the air outdoors! In fact, some American doctors say that 50% of the illnesses have2to do with the polluted indoor air.

A lot of pollution comes from indoor activities3smoking and cooking. As most people 4about 80%-90% of their time inside buildings, it is important to take indoor air pollution seriously, too.

Air pollution influences our health5. When the air is polluted, not only young children and old people6from it,7people with health problems suffer as well. Indoor air pollution can8people's eyes, noses and throats. Air pollution, both indoor and outdoor, can also9to lung cancer and heart disease! In the great London fog in 1952, 4, 000 people died in a few days10the pollution! It is said that half a million young children and women die each year in India because of indoor air pollution!