Which of the following is not an air pollutant?

Correct option is D

The correct answer is Oxygen.
Oxygen:
· Oxygen (O₂) is not an air pollutant as the atmospheric composition contains 78 percent nitrogen and 21 percent oxygen by proportion.
Carbon monoxide:
· Carbon monoxide (CO) is one of the most serious air pollutants.
· It is a colorless and odorless gas, highly poisonous to living beings because of its ability to block the delivery of oxygen to the organs and tissues.
Methane:
· Methane (CH₄) is a harmful air pollutant and greenhouse gas that causes one million premature deaths each year.
· Methane is another potent greenhouse gas. It is 80 times more potent than carbon dioxide at warming over a 20-year period.
Nitrogen oxide:
· Nitrogen oxides (NO) have long been recognized as toxic environmental pollutants.
Thus, Oxygen is not an air pollutant.
Information Booster
· Air pollutants cause air pollution.
· Any undesirable change in the physical, chemical, and biological characteristics of air that exerts adverse effects on human beings is defined as air pollution.
· Air pollutants are the harmful substances found in the atmosphere that harm the ecological system.
· There are two types of air pollutants:
· Gaseous air pollutants: These are oxides of sulphur, nitrogen and carbon, hydrogen sulphide, hydrocarbons, ozone, and other oxidants.
· Particulate pollutants: These are dust, mist, fumes, smoke, smog, etc.
· Major air pollutants are carbon monoxide, sulphur dioxide, nitrogen oxide, fly ash, methane, suspended particulate matter, etc.