WHO Updates Air Quality Guidelines, But Are They Safe?

After over 16 years of no updates, the World Health Organization (WHO) finally updated its air quality guidelines including its recommended limits for one of the world’s biggest killers, PM2.5 air pollution. The WHO lowered their recommended annual limit of PM2.5 pollution by half, from 10 micrograms to 5 micrograms. 

At Smart Air, we previously discussed why the WHO PM2.5 guidelines are unsafe because there is a lot of research showing PM2.5 is deadly at far lower levels.

Why the WHO Updated Its Air Pollution Guidelines

First, let’s look at what was wrong with the previous WHO recommended safe air pollution levels. The WHO air pollution guidelines were last updated in 2005. Since 2005, there have been many major new findings on the effects of air pollution on our health. These findings include strong links of higher mortality and cardiovascular rates at pollution levels below the recommended limits. We have also learned much more about how pollution affects infertility, new born’s health, and brain health

During the years of 1987 to 2005 (in which the WHO made two revisions to their guidelines), there were approximately 130,000 studies on the effects of air pollution on our health.

Air Pollution Effects on Health (1987-2005)

Since the WHO’s last update of their air quality guidelines in 2005, there have been 177,000 new studies.

Air Pollution Effects on Health (2005-2021)

At the time of the last update, the known effects of air pollution were vastly underestimated. The recommendations were long due for an update to reflect the new research.

What is New in the Updated WHO Air Quality Recommendations?

The WHO updated its air quality recommendations by lowering the annual PM2.5 limit from 10 to 5 micrograms, and the 24 hour PM2.5 limit from 25 to 15 micrograms.

WHO updated air quality guidelines

Based on new research since the last update in 2005, the WHO lowered six of their recommendations including PM2.5. The limit for one pollutant, sulfur dioxide, actually increased two-fold.

Since 99% of the world’s population lives in places where the WHO safe air guidelines are not met and many countries are far from reaching these goals, the WHO created interim targets. These interim targets are more achievable for countries that are far above the levels, yet reductions to these levels would still result in a significant reduction in disease. The new guidelines also offer additional recommendation levels, such as for peak season O₃ and 24-hour NO₂ and CO.

PollutantAveraging Time2005 AQGs2021 AQGs
PM2.5 μg/m3Annual105
24 Hour*2515
PM10 μg/m3Annual2015
24 Hour*5045
O3 μg/m3Peak Season#60
8 Hour*100100
NO2 μg/m3Annual4010
24 Hour*25
SO2 μg/m324 Hour*2040
CO, mg/m324 Hour*4
* 99th percentile (i.e. 3–4 exceedance days per year). # Average of daily maximum 8-hour mean O3 concentration in the six consecutive months with the highest six-month running- average O3 concentration. Note: Annual and peak season is long-term exposure, while 24 hour and 8 hour is a short-term exposure

Are the New Updated WHO Recommended Safe Air Quality Limit Actually Safe?

It is good to see the WHO updating their air quality guidelines. But in reality,  there is actually no “safe level” of air pollution. Even small amounts of particulate pollution increase your risk of various diseases and death. Giving “safe level” recommendations for air pollution can give people a false sense of safety.

In fact, research shows that pollution at low levels has the greatest impact on our bodies.

Read More: Why Low Levels of Air Pollution Actually Cause the Most Harm

Air Pollution's Effect on Mortality- WHO Air Quality Guidelines are Unsafe

As we now know, particulate pollution is similar to lead in that there is no safe level of intake. Even low levels can be consequential to your health. The WHO has emphasized this when discussing safe levels of lead intake and in their lead guidelines. 

Bottom Line: Updated WHO Air Quality Guidelines

The recently updated WHO air pollution guidelines are just that – guidelines. We should not be complacent breathing air that’s within the limits. Data shows that even these levels of pollution are still harmful to health.

Smart Air


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