The most obvious flaw in air freshener is the possible damage to the human body of the ingredients it contains. There are many kinds of air fresheners sold on the market, but basically is composed of ethyl ether, essence and so on, these substances in the air after the chemical decomposition of the gas produced by some components itself is air pollution, which is actually aggravating the vehicle air pollution degree, long-term use of the human body will produce undesirable stimulation. In addition, the air freshener contains an aromatic agent on the human nervous system will also be harmful to stimulate the child's respiratory mucosa and so on. Air Freshener also has a disadvantage is that it does not decompose harmful gases, to achieve the purpose of fresh air. Its role is to cover the odor through the dissemination of odor, rather than with the air caused by the smell of the gas reaction, that is, the effect of air freshener does not clean the air of harmful gases, it is only by confusing the smell of people to "dilute" odor.