What Level of PM2.5 Is Safe? New Research Reveals

The WHO’s guideline limit for PM2.5 is 5 micrograms. But research shows reducing PM2.5 levels under 5 micrograms has significant health benefits and reduces mortality. What is the safe limit of PM2.5?

Is the WHO PM2.5 Guideline of 5 Micrograms Safe?

The WHO PM2.5 guideline is not intended to represent the safe limit of PM2.5. Rather, it is intended to provide targets for policymakers. In fact, the WHO itself stated that there are negative health effects below the limit.

The risk for various outcomes has been shown to increase with exposure and there is little evidence to suggest a threshold below which no adverse health effects would be anticipated.

WHO Global update 2005

In addition, since the release of the WHO’s first guidelines in 1987, the PM2.5 guideline has been lowered multiple times, from 15 to 10 micrograms, and again from 10 to 5 micrograms. This pattern is very similar to how the CDC’s lead standards have changed over the decades:

Lead guidelines has lowered over the decades

Read More: The WHO Updates PM2.5 Guidelines in 2021

Similar to Lead, There is No Safe Level of PM2.5

A new study tried to find the answer to “What is the safe limit of PM2.5?”. They studied 7.1 million adults in one of the world’s lowest PM2.5 environments. The lowest observed PM2.5 concentration of 2.5 micrograms was used as the base level.

Study shows there is no safe level of PM2.5 air pollution

As shown in the graph above, even slight increases in PM2.5 from the base level have significant increases in mortality. This shows that even in areas with the “best air quality in the world“, lowering PM2.5 further can have significant health benefits and save lives.

Lowering levels below 2.5 micrograms would likely show a similar significant reduction in mortality. There are simply not enough places with such low levels to gather data from.

Save Levels of PM2.5

Similar to lead, there is no safe level of PM2.5. Even at low levels, reducing PM2.5 further can signifcantly reduce mortality.

Smart Air




Smart Air low cost purifiers

Smart Air — 聪明空气(北京)科技有限公司 — 是一家小型社会企业,致力于为室内空气污染问题提供价格实惠,有实验数据支持的空气净化器。我们的教育沙龙横跨亚洲多个国家,旨在向大家传播空气污染的防护措施。

Certified B-Corp air purifier company