India should monitor PM1, the least visible particle in air

Although there has been an immense rise in all kinds of pollutants, the focus has mostly remained on PM2.5 and PM10, and less on ultrafine particles qualified under PM1
Combustion of fuels usually leads to generation of PM1. Photo: Flickr
Combustion of fuels usually leads to generation of PM1. Photo: Flickr

Increasingly, cities around the world are turning into gas chambers. Countries are grappling with regulatory challenges in curbing the growing particulate matter in the air.

The World Health Organization (WHO) has set regulatory standards to measure and monitor air pollution by identifying key pollutants.

Among various pollutants, particulate matter PM2.5 (particulate matter with aerodynamic diameter <2.5 μm) and PM10 (particulate matter with aerodynamic diameter <10 μm), often shows the strongest evidence for adverse health effects.

Particulate matter consists of discrete particles that range in size over several orders of magnitude. In many countries, inhalable particulate matter PM10 and PM2·5 have been regarded as criteria pollutants because several studies have documented the adverse health effects of PM10 and PM2.5.

Size is an important determinant of health effects of particulate matter. Previous epidemiological studies suggested that PM2.5 has stronger effects on cardiorespiratory disorders than PM10. However, there is very limited knowledge regarding which specific size fraction below 2.5 μm is mainly responsible for the observed health effects.

Particularly, PM2.5 has been labelled a slow killer, which has been of increasing public concern. It caused an estimated 2.9 million deaths and 69.7 million disability-adjusted life-years (DALYs) in 2013 globally.

Ambient PM2.5 contributes to a high burden of disease in East Asian countries including China. China is now experiencing exceptionally high levels of particulate matter air pollution, especially in densely populated cities.

Numerous studies have confirmed associations between exposure to PM2·5 and adverse health effects, including cardiovascular and respiratory diseases, neonatal conditions, and hospital admissions.

However, the scientific community has detected a rising concern of PM1.While PM2.5 is just around 30 times finer than the thickness of a human hair, PM1 is 70 times finer than the human hair and even WHO does not define acceptable standards for these ultra-fine particles.

This particulate is more likely to reach deeper into the respiratory system carrying with it, more toxins from anthropogenic emissions. The ultra-fine particles are small enough to infiltrate the body through the tiny pores in the skin which is meant for perspiration and bodily functions.

A study in China claimed that PM1 contributed to 80 per cent of PM2.5. Evidence for health effects of PM1 is very limited currently, because it is not routinely monitored internationally.

So far, the standards for PM1 have not been proposed by WHO or any other government agencies. While PM2.5 can reach your lungs, PM1 can enter your bloodstream.

The primary sources of PM1 are vehicular and industrial emissions. But till date there are not enough studies in the world on PM1.

Neither the WHO nor the United States Environment Protection Agency or India’s Central Pollution Control Board has been able to set its standards. Its effect on health and its toxicity are still bein

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