| abstract |
(57) [Summary] [PROBLEMS] To effectively control air pollution caused by exhaust gas. SOLUTION: Light output from a light projecting unit 11 is reflected by a reflector 13 and received by a light receiving unit 12. The concentration detector 31 analyzes a change in the spectrum of the light received by the light receiver 12, and measures the concentration of the pollutant contained in the air. Then, when it is determined that the measured concentration is equal to or higher than the predetermined threshold, the purified water supply units 4-1 and 4-2 From which purified water is sprayed to remove contaminants. |