The World Health Organization updated the Air Quality Guidelines (AQGs) for the first time after 16 years (the last big revision was back in 2005), and they are much stricter. Nearly 80% of the fatalities worldwide caused by air pollution can be reduced if countries meet the new annual PM2.5 guideline.
In short, set side by side to earlier WHO recommendations, the new Air Quality Guidelines (AQGs):
- introduce stricter guidelines
- increase confidence in the evidence of health effects happening at lower levels than previously recognized;
- utilize new methods for evidence synthesis and guideline formulation;
- strengthen the evidence on health impacts;
- give new interim objectives and additional AQG levels, such as for peak season O3 and 24-hour NO2 and CO;
- offer new good practice statements on the management of certain types of PM (i.e., black carbon/elemental carbon, ultrafine particles, and particles arising from sand and dust storms).
What are the NEW WHO Air Quality Guidelines (AQGs)?
The WHO Global Air Quality Guidelines (AQGs) have been revised to include recommendations for air quality guideline levels as well as interim objectives for six major air contaminants: particulate matter (PM2.5 and PM10), ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2), and carbon monoxide (CO) are all addressed in the recommendations (AQGs). 
They also provide qualitative statements on good practices for managing certain types of particulate matter (PM), such as black carbon/elemental carbon, ultrafine particles, and particles originating from sand and dust storms, for which quantitative evidence is insufficient to derive AQG levels.
The recommendations establish the levels of air quality required to preserve public health across the world, based on the most up-to-date scientific information. The AQGs also serve as a guide for determining if and by how much a population’s exposure exceeds limits that might be harmful to their health.
At the international, national, and municipal levels, guideline values for certain pollutants can be used as an evidence-based reference to assist decision-makers in defining legally enforceable standards and targets for air quality management. They are also a useful tool for designing effective strategies to reduce pollutant emissions and concentrations and, as a result, to safeguard human health.
What are the main differences between the 2021 and 2005 AQGs?
The new WHO Global Air Quality Guidelines (AQGs) from 2021 demonstrate the harmful effects of air pollution on human health at considerably lower concentrations than previously thought. The guidelines propose new air quality standards to safeguard people’s health by lowering levels of important air contaminants, some of which are also linked to climate change.
We see the most significant differences at levels of the Particulate Matter under 2.5 microns (PM2.5) and nitrogen dioxide (NO2). The new annual guideline for PM2.5 is 2 times stricter than the old one, changed from 10 to 5 µg/m3, and the daily guideline is changed from 25 to 15 µg/m3. The new annual guideline for NO2 levels is 4 times stricter, changed from 40 to 10 µg / m3. Also, a new daily average value for NO2 was added for the first time in this issue of AQGs (2021).
Around 80% of fatalities worldwide attributable to PM2.5 exposure might be prevented if countries met the NEW annual PM2.5 AQG threshold of 5 µg/m3. Reaching the interim goals will also have significant health advantages. In the case of PM2.5, achieving intermediate goal 4 (the same level as the AQG from 2005 = 10 µg/m3) would result in a roughly 48 % reduction in overall fatalities due to PM2.5 exposure.
Since the previous WHO global update in 2005, there has been a significant increase in evidence demonstrating how air pollution impacts several areas of health. As a result, and following a thorough assessment of the available data, WHO has lowered virtually all AQGs levels, warning that exceeding the new air quality guideline limits has considerable health risks. Adherence to them, on the other hand, might save millions of lives.
How are AQGs developed?
WHO recommendations are developed through a thorough process of examining and evaluating evidence that involves many groups of experts with clearly defined responsibilities. Based on the distilled evidence given by the systematic review team, a guideline creation committee determines the scope and main issues of the guidelines and creates the recommendations. Furthermore, an external review committee gives essential feedback, and the WHO steering group, which is made up of WHO personnel from all regions, monitors the project’s execution. More than 500 publications were identified for systematic review and syncretization to get the most up-to-date evidence for determining the new AQG values.
These guidelines provide no suggestions concerning combined exposures of any type. People are frequently exposed to a variety of air contaminants throughout their daily lives. The World Health Organization recognizes the importance of creating comprehensive models to assess the impact of various exposures on human health. However, the present guidelines offer recommendations for each air pollutant individually since the majority of data on air quality and health still focuses on the influence of single air pollutants on health outcomes.
Why are the WHO’s AQGs so important?
According to WHO estimates, about 7 million people die prematurely each year, mostly from noncommunicable illnesses, as a result of the combined impacts of ambient and home air pollution. This is partially due to increased exposures in low- and middle-income nations, but it’s also related to the fast-rising incidence of noncommunicable diseases (NCDs) throughout the world as a result of population aging and lifestyle changes. Air pollution raises morbidity and mortality from non-communicable cardiovascular and respiratory diseases, which are the leading causes of death worldwide; it also raises the disease burden from lower respiratory tract infections, as well as preterm birth and other causes of death in children and infants.
Although air quality in high-income nations has steadily improved, pollutant concentrations still exceed the WHO AQGs for numerous contaminants in many places. In 2019, more than 90% of the world’s population resided in locations where PM2.5 concentrations exceeded the WHO’s 2005 air quality guideline for long-term exposure. Because of large-scale urbanization and economic development that has primarily relied on inefficient burning of fossil fuels, such as coal, as well as inefficient domestic fuel usage and industry, air quality has typically deteriorated in most low- and middle-income nations. Disparities in air pollution exposure, on the other hand, are widening globally.
How do the recommendations differ from the European air quality directives?
Will be continued…
- World Health Organization. Air quality guidelines: global update 2005: particulate matter, ozone, nitrogen dioxide, and sulfur dioxide. World Health Organization, 2006.