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‘Very Unhealthy’ Air-Quality Index Level

All About the “Very Unhealthy” Air-Quality Index Level

  • We classify conditions as moderate if

    • Short-term (one-hour) concentrations are 352–526 µg/m3
    • Eight-hour average concentrations are 201–300 µg/m3
    • 24-hour average concentrations are 151–250 µg/m3
  • The AQI for very unhealthy air quality is 201–300

  • The visibility during very unhealthy air quality is usually 1–1.25 miles

  • Health effects expected

    • Significant aggravation of heart or lung disease, premature mortality in persons with cardiopulmonary disease and the elderly
    • Significant increase in respiratory effects in general population
  • Caution statements?

    • Avoid prolonged or heavy exertion
    • Stay indoors and avoid exertion
  • Protective actions?

    • If symptomatic, evacuate to cleaner air shelter or leave area, if safe to do so
Last modified on April 21st, 2017
Posted on April 21st, 2017