All of the following are criteria pollutants except a. Lead b Mercury C. Ozone d. Carbon monoxide Nitrogen dioxide

The correct answer is b. Mercury.<br /><br />Criteria pollutants are a group of air pollutants that have been regulated by national environmental laws and regulations. The six criteria pollutants are:<br /><br />1. Lead (a)<br />2. Ozone (c)<br />3. Carbon monoxide (d)<br />4. Nitrogen dioxide (e)<br />5. Sulfur dioxide<br />6. Particulate matter<br /><br />Mercury is not considered a criteria pollutant, but it is a toxic air pollutant that is regulated under the Clean Air Act.