People can live for 5 weeks without eating, and can live for 5 days without drinking water, but if there is no air, they can’t live for 5 minutes. So, we can see how important the air is. People spend most of their time indoors. According to a survey by the China National Standards Institute, 68% of diseases are caused by indoor pollution! American experts have found that there are more than 500 kinds of volatile organic compounds in indoor air, including more than 20 kinds of carcinogens and more than 200 kinds of pathogenic viruses. The main hazards are: bismuth, formaldehyde, benzene, ammonia and esters.