What are the new World Health Organisation Air Quality Guidelines?

By Shazelle James, WKC Group

The World Health Organisation’s (WHO’s) Air Quality Guidelines (AQGs) serve as a global target for national, regional and district governments to aim for in order to manage air pollution.

The WHO AQGs, first released in 1987, have undergone numerous updates over the years with the most recent global version being published in 2021 subsequent to the prior update in 2005. These AQGs are a set of evidence-based recommendations of limit values for specific air pollutants developed to assist countries to achieve air quality that does not negatively affect public health. WHO updates the AQGs on a regular basis to ensure continued relevance.

The 2021 Updated WHO AQGs

In the 2021 updated WHO AQGs recommendations on AQG levels together with interim targets for particulate matter with an aerodynamic diameter smaller than 10 μm and 2.5 μm (PM10 and PM2.5, respectively), ozone (O3), sulphur dioxide (SO2), nitrogen dioxide (NO2) and carbon monoxide (CO) have been formulated. A comparison of the 2005 and 2021 WHO AQGs are presented in the table below.


While achieving the AQG level is considered the ultimate goal, this may be a be a difficult task for countries and regions struggling with high air pollution levels. Taking note of this, interim targets have been proposed; the achievement of which will be considered a critical indicator to improving air quality and health condition for populations.

It should be noted that AQGs for pollutants and averaging periods not mentioned above remain valid. A list of the unchanged, valid WHO AQGs is provided in the table below.


The present 2021 guidelines are applicable to both indoor and outdoor environments but, do not cover occupational settings. The AQGs are of specific significance to policy-makers, law makers and technical experts, national and local authorities as well as academics, health and environmental practitioners.

Source: World Health Organisation

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