Air pollution one of the biggest environmental threats to human health: WHO

PTI, Sep 22, 2021, 7:38 PM IST

New Delhi: Air pollution is one of the biggest environmental threats to human health alongside climate change, the World Health Organisation said on Wednesday 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.

“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,” it said in a statement.

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.

AQG is an annual mean concentration guideline for particulate matter and other pollutants.

“Since WHO”s last 2005 global update, there has been a marked increase of evidence that shows how air pollution affects different aspects of health. For that reason, and after a systematic review of the accumulated evidence, WHO has adjusted almost all the AQGs levels downwards, warning that exceeding the new air quality guideline levels is associated with significant risks to health,” the WHO said.

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).

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.

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.

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.

“The health risks associated with particulate matter equal or smaller than 10 and 2.5 microns (µm) in diameter (PM 10 and PM 2.5, respectively) are of particular public health relevance. Both PM 2.5 and PM 10 are capable of penetrating deep into the lungs, but PM 2.5 can even enter the bloodstream, primarily resulting in cardiovascular and respiratory impacts, and also affecting other organs.

“PM is primarily generated by fuel combustion in different sectors, including transport, energy, households, industry and agriculture,” the WHO noted.

It stressed that adhering to these guidelines could save millions of lives.

“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. In children, this could include reduced lung growth and function, respiratory infections and aggravated asthma.

“In adults, ischaemic heart disease and stroke are the most common causes of premature death attributable to outdoor air pollution, and evidence is also emerging of other effects such as diabetes and neurodegenerative conditions,” it further said.

According to WHO, this puts the burden of disease attributable to air pollution on par with other major global health risks such as unhealthy diet and tobacco smoking.

“Air pollution is one of the biggest environmental threats to human health, alongside climate change. Improving air quality can enhance climate change mitigation efforts, while reducing emissions will in turn improve air quality,” it said.

The global health body added that by striving to achieve these guideline levels, countries will be both protecting health as well as mitigating global climate change.

In 2013, outdoor air pollution and particulate matter were classified as carcinogenic by WHO”s International Agency for Research on Cancer (IARC).

The guidelines also highlight good practices for the management of certain types of particulate matter (for example, black carbon/elemental carbon, ultrafine particles, particles originating from sand and dust storms) for which there is currently insufficient quantitative evidence to set air quality guideline levels, the health body said.

“Air pollution is a threat to health in all countries, but it hits people in low- and middle-income countries the hardest,” said WHO Director-General Tedros Adhanom Ghebreyesus.

“WHO”s new Air Quality Guidelines are an evidence-based and practical tool for improving the quality of air on which all life depends. I urge all countries and all those fighting to protect our environment to put them to use to reduce suffering and save lives,” he said.

The goal of the guideline is for all countries to achieve recommended air quality levels, the WHO said.

Conscious that this will be a difficult task for many countries and regions struggling with high air pollution levels, the health body has proposed interim targets to facilitate stepwise improvement in air quality and thus gradual, but meaningful, health benefits for the population.

“Almost 80 per cent of deaths related to PM 2.5 could be avoided in the world if the current air pollution levels were reduced to those proposed in the updated guidelines,” according to a rapid scenario analysis performed by WHO.