Indoor environment for thousands of varieties of hazardous substances, the most important are : radon, radioelement, formaldehyde, benzene, ammonia, PVC, nitrogen oxides and carbon oxides.

• 室内环境的有害物质达数千种之多，其中最主要的有：氡、放射性元素、甲醛、苯、氨、聚氯乙烯、氮氧化物和碳氧化物等。