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
[{'content': 'All are indicators for air pollution , except ? \nSelect and explain. \nA. CO2, B. SO2, C. Soiling Index, D. Smoke index', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. is \'a\' i.e., CO2 o Carbon dioxide is also an air pollutant, but it is not used as an air pollution indicator. o Park writes -- "It is not commonly regarded as an air pollutant although man generates enormous amount of it in combustion process using coal, oil and gas. Carbondioxide is a natural constituent of the air It does not take pa in any significant chemical reactions with other substances in the air". o The best indicators of air pollution are Sulphur dioxide Smoke (soiling index) Suspended paicles', 'role': 'assistant'}]