People living in highly-polluted cities such as Delhi may have an idea when the air they breathe turns foul from the air quality index (AQI) regularly put out by the Central Pollution Control Board (CPCB). But it is not easy is it to know how toxic the air is, unless they know the chemical composition of the tiny particles they breathe.

Among these tiny particles, called particulate matter (PM), particles that are smaller than 2.5 microns in size, or PM2.5, are said to be more dangerous. But currently, we have no indigenous technology to monitor them and ascertain their chemical footprints.

Besides, distinguishing these tiniest particles on the basis of their chemical composition can help experts know where these particles come from — from vehicles, crop residue burning or industries. This source apportionment is still an evolving area and there are only a few pilot projects currently going on in the country.

Now, Tarun Gupta, a professor of civil engineering in the Indian Institute of Technology Kanpur (IITK), who developed one such technology has successfully transferred it for commercial production.

While real-time air pollution monitors are increasingly used for air quality, it is not possible to conduct the chemical species analysis with them, said Gupta who has been working on it since 2013-14 as a part of project funded by the Department of Atomic Energy.

“They approached us because they wanted to monitor traces of uranium and thorium in the air in areas around where minerals containing these radioactive elements are mined. The imported ones were very expensive,” said Gupta, who developed and supplied a few such samplers to the department.

Last week, the institute transferred the technology to Airshed Professional Private Ltd, a firm incubated at IITK and owned by alumnus Dhirendra Singh.

Called Multiple slit nozzle high volume PM2.5 impactor, the technology provides for better particle collection efficiency even at low pressures. The impactor is designed in a manner that certain high volume respirable dust samplers already available in the market can be easily retrofitted with the impactor assembly without disturbing/changing their original set-up.

“Using the impactor, cities may be able to analyse air samples at 15 minutes to 2 hour intervals to know all the chemical species present in the air. This would help them know how toxic the air that citizens breathe and take policy decisions accordingly,” said Gupta.

Currently, under the National Air Monitoring Plan, both realtime monitors and manual monitors are installed across the country for monitoring air quality. While there 230 real-time monitors, the bulk — around 800 — are manual air pollution monitoring units, but they mostly measure only PM10.

“The new impactor which costs several times cheaper than those imported can be retrofitted with the existing units to measure PM2.5 as well,” said Singh. Besides, there are around 2,000 such air quality monitoring units installed by industries to comply with regulatory requirements.

Globally, environmental monitoring is emerging as a huge business. According to a report by the US Department of Commerce, India’s overall environmental technologies market, including goods and services is valued at $17.87 billion in 2017.

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