GS Paper - 3 (Environment)

Air pollution is one of the biggest environmental threats to human health alongside climate change, the World Health Organisation said on 22 September 2021 as it released its new air quality guidelines for the first time since its last global update in 2005. The World Health Organisation (WHO) said its new air quality guidelines (AQGs) aim to save millions of lives from air pollution.

What the guidelines said

  1. New World Health Organisation Global Air Quality Guidelines provide clear evidence of the damage air pollution inflicts on human health, at even lower concentrations than previously understood.
  2. The guidelines recommend new air quality levels to protect the health of populations, by reducing levels of key air pollutants, some of which also contribute to climate change.
  3. AQG is an annual mean concentration guideline for particulate matter and other pollutants.
  4. WHO's new guidelines recommend air quality levels for six pollutants -- particulate matter (PM) 2.5 and PM 10, ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2) and carbon monoxide (CO).
  5. The 2021 guidelines stipulate that PM 10 should not exceed 15 µg/m3 (micrograms per cubic metre of air) annual mean, or 45 µg/m3 24-hour mean. According to the 2005 guideline, the limit was 20 µg/m3 annual mean or 50 µg/m3 24-hour mean for PM 10.
  6. They recommend that PM 2.5 should not exceed 5 µg/m3 annual mean, or 15 µg/m3 24-hour mean. As per the 2005 guideline, the limit was 10 µg/m3 annual mean or 25 µg/m3 24-hour mean for PM 2.5.
  7. Under the 2005 guideline, the AQG level of another pollutant Nitrogen Dioxide was 40 µg/m3 annual mean which has now been changed by the WHO to 10 µg/m3.


  1. PM is primarily generated by fuel combustion in different sectors, including transport, energy, households, industry and agriculture.
  2. Every year, exposure to air pollution is estimated to cause 7 million premature deaths and result in the loss of millions more healthy years of life.
  3. In children, this could include reduced lung growth and function, respiratory infections and aggravated asthma.
  4. In 2013, outdoor air pollution and particulate matter were classified as carcinogenic by WHO's International Agency for Research on Cancer (IARC).
  5. The goal of the guideline is for all countries to achieve recommended air quality levels.