Which pollutant is a criteria pollutant that is a fine particulate matter (PM2.5)?

Which pollutant is a criteria pollutant that is a fine particulate matter (PM2.5)?

• A. PM2.5
• B. O3
• C. NO2
• D. Pb

Answer: (A)

Fine particles with a diameter of 2.5 micrometers or smaller are labeled PM2.5. This size allows them to penetrate deep into the lungs and even enter the bloodstream, making PM2.5 a major air-quality concern that is specifically designated as a criteria pollutant with an established national standard. Among the options, the pollutant that fits both parts of the question is PM2.5 itself, since it is defined as a fine particulate matter and is one of the criteria pollutants tracked by the standards. The other choices are not fine particulate matter by definition: ozone is a gaseous pollutant formed by photochemical reactions; nitrogen dioxide is a gas; lead is a metal pollutant that is regulated, but not described by the PM2.5 size category.

Fine particles with a diameter of 2.5 micrometers or smaller are labeled PM2.5. This size allows them to penetrate deep into the lungs and even enter the bloodstream, making PM2.5 a major air-quality concern that is specifically designated as a criteria pollutant with an established national standard. Among the options, the pollutant that fits both parts of the question is PM2.5 itself, since it is defined as a fine particulate matter and is one of the criteria pollutants tracked by the standards. The other choices are not fine particulate matter by definition: ozone is a gaseous pollutant formed by photochemical reactions; nitrogen dioxide is a gas; lead is a metal pollutant that is regulated, but not described by the PM2.5 size category.