How can carbon dioxide be considered a pollutant when it is a natural component of air? a. carbon dioxide is considered a pollutant even though it is a natural component of air, because it is harmful to all living organisms. b. carbon dioxide is considered a pollutant when larger concentrations than normal are present in the air as a result of human activity. c. carbon dioxide is considered a pollutant, because it forms harmful chemicals when mixed with other pollutants in the air. d. carbon dioxide cannot be considered a pollutant under any circumstances.

b. Carbon dioxide is considered a pollutant when larger concentrations than normal  are present in the air as a result of human activity.

Explanation:

Carbon dioxide is a useful gas in our atmosphere because it is an important substrate in the process of photosynthesis. Its normal percentage in the air is 0.0391 % but when it exceeds this optimum level in the atmosphere it acts as a pollutant. It is a green house gas which has the tendency to trap heat radiations. More carbon dioxide means more green house effect which will lead to global warming, melting of glaciers and extreme weathers which is a life threatening condition.

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