Which statement about primary and secondary standards is true?

Which statement about primary and secondary standards is true?

• A. Primary standards protect human health and secondary standards protect public welfare
• B. Primary standards protect public welfare and secondary standards protect human health
• C. They refer to treatment levels required by air pollution control equipment
• D. There is no difference between them

Answer: (A)

The main idea here is that there are two types of ambient air quality standards with different protection goals. Primary standards are health-based, set to protect human health with an adequate margin of safety for all people, including sensitive groups. Secondary standards, on the other hand, are designed to protect public welfare—things like crops, wildlife, water and air quality affecting ecosystems, property, and even visibility and climate effects. So the true statement is that primary standards protect human health and secondary standards protect public welfare. Some pollutants have both types of standards, and while they may end up at similar levels, their purpose is distinct: health protection versus welfare protection. The other options mix up these goals or mischaracterize what standards regulate, since standards describe ambient air quality limits, not treatment levels for pollution-control equipment.

The main idea here is that there are two types of ambient air quality standards with different protection goals. Primary standards are health-based, set to protect human health with an adequate margin of safety for all people, including sensitive groups. Secondary standards, on the other hand, are designed to protect public welfare—things like crops, wildlife, water and air quality affecting ecosystems, property, and even visibility and climate effects.

So the true statement is that primary standards protect human health and secondary standards protect public welfare. Some pollutants have both types of standards, and while they may end up at similar levels, their purpose is distinct: health protection versus welfare protection. The other options mix up these goals or mischaracterize what standards regulate, since standards describe ambient air quality limits, not treatment levels for pollution-control equipment.