This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and Health, Subject name: Social & Preventive Medicine
Soiling index is measure for - 
Select and explain. 
A. Air pollution, B. Water pollution, C. Faecal contamination, D. Milk contamination
A: Air pollution
Answer: A: Air pollution 
Explanation: Arts, is 'a' i.e., Air pollution Monitoring of air pollutiono Monitoring of air pollution is done by : -Sulphur dioxide.Gritt and dust measurement.Co-efficient of haze.Air pollution index.Smoke or soiling index