* Fine dust: Means fie dusts with diameter of 10㎛ or less which floats in the atmosphere for a long period as polluting material including many polluting materials together with sulfurous acid gas, nitrogen, oxide, lead, ozone, carbon oxide, etc.
* It is known to have high likelihood of harmful effect on the human body such as increasing disease occurrence rate and death rate of elderly, children, pregnant women, etc. and causing respiratory diseases, etc. As it is composed of properties harmful to the human body and particles are too small, it easily penetrates into alveolus and also stays for long period.
* Government of various countries started to establish measures for pollutions and standards for pollution to reduce harmful effect of fine dusts on human body and environment.