This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Smoke index is used for- 
Select and explain. 
A. Air pollution, B. Soundpollution, C. Excreta, D. None
A: Air pollution
Answer: A: Air pollution 
Explanation: Monitoring of air pollution
Monitoring of air pollution is done by : -

Sulphur dioxide.
Gritt and dust measurement.
Co-efficient of haze.
Air pollution index.
Smoke or soiling index