阅读理解
As soon as you walk into the kitchen, the smell hits you. Phew! You should have taken out the garbage yesterday. You bring the trash outside, but when you return to the kitchen, it still smells awful. What should you do to get rid of the stink?
Many people in this situation will reach for an air freshener. Air fresheners are an easy and quick way to make the room smell better. There are many different types of air fresheners, including sprays, candles, and cleaners. No matter what form it takes, an air freshener fights bad smells in one of three basic ways.
The first way is by masking, or hiding, the unpleasant smell. Sprays and candles work in this way. These air fresheners cover up the bad smell by overpowering it with a stronger smell. This does not get rid of the bad smell. Instead, it covers it up with something else. Sometimes this makes the room smell better. Sometimes, it makes the room smell like a combination of perfume and garbage. Masking fresheners are a good choice if you do not mind strong scents.
Some air fresheners, like some cleaning products, work by changing your body instead of the air around it. When you use these types of products, special chemicals actually stop the scent receptors in your brain from noticing the bad smells. These types of air fresheners work well, but they may be dangerous for people with conditions such as asthma(哮喘) or allergies.
A third kind of air freshener fights against the bad smells in the air itself. These air fresheners use charcoal(碳) or chemicals called oxidizing agents to "clean" the air. Some bad smells are caused by organic matter, which are basically materials that are alive, used to be alive, or came from living things. These include rotten food, mold, and pet smells. The charcoal or chemicals remove these things from the air. Instead of simply covering up the bad smell, these air fresheners work to eliminate it altogether.
If you are worried about using chemicals or heavy fragrance in your house, you may not want to use an air freshener at all. In this case, your best choice may simply be to open up the windows or turn on a fan — and, of course, to remember to take out the garbage more often!
