Keep in mind, the standards are periodically reviewed and sometimes may be revised, establishing new standards. The most recently established standards are as follows:
- Carbon monoxide is 9 parts per million (ppm) measured over 8 hours and 35 ppm measured over 1 hour.
- Lead is 0.15 micrograms per cubic meter of air (µg/m³) measured over a rolling 3-month average.
- Nitrogen dioxide is 100 parts per billion (ppb) measured over 1 hour and 53 ppb measured over 1 year.
- Ozone is 0.070 ppm measured over 8 hours.
- Particle pollution (PM2.5) is 9.0 µg/m³ for primary measured over 1 year and 15.0 µg/m³ for secondary measured over 1 year.
- Particle pollution (PM10) is 150 µg/m³ measured over 24 hours.
- Sulfur dioxide is 75 ppb for primary measured over 1 hour and 0.5 ppm for secondary measured over 3 hours .
