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| Last Updated:: 01/04/2016

Toxicity hazards of Environmental Toxicants.

NEW DELHI: Delhi's air pollution levels are among the worst in the world but new research is pointing at something even more worrying. A government agency that recently started monitoring the most dangerous class of particulate pollutants — ultrafine particulate matter or PM1 — found its levels to be quite high even in the low-pollution pre-monsoon season in comparatively cleaner locations of the city such as central Delhi's Lodhi Road. PM1 is the tiniest class of pollution particles. Studies show it's the primary cause of pollution-linked incidence of cardiovascular disease. Much finer than PM2.5, PM1 particles can easily penetrate very deep into the lungs or enter the blood stream.

Currently, no safe standards have been set for PM1. Yet, there are several reasons why experts are ringing the alarm bells on the pollutant's levels in Delhi. According to monitoring agency SAFAR, PM1 levels on certain days had peaked to 70 micrograms per cubic metre, higher than even the national safe standard for PM2.5, which is 60mg/m3. PM1 is a fraction of PM2.5 emissions but SAFAR scientists say their levels should be extremely low or none because of their health implications. "On most days, the proportion of PM1 is about 35% of the PM2.5 emissions but on Thursday it was more than 50% of PM2.5 emissions. This shows that people are breathing in ultrafine particles that have serious health impacts," said Gufran    Beig, project         director,  SAFAR. PM1 levels remain high even in wet weather because rain doesn't wash away very fine particles, Beig said.

"If PM1 is 50% of PM2.5 concentrations, we should really be worried," said Anumita Roychowdhury of Centre for Science and Environment.

T K Joshi, director of Centre for Occupational and Environmental Health (COEH), explains why this is so. "There is no safe standard for PM1 simply because there is no level that can protect everyone from its health impacts. There are people who are extremely sensitive to even very low levels. The current thinking is that we reduce the fine particles as much as possible. It is a very expensive proposition though," Joshi said. He said PM1 particles can enter the blood and circulate, affecting the inner walls of arteries and causing cardiovascular problems. "Since they get diffused with the blood, new research also suggests they can travel to the brain and          are     linked           to       strokes,"      added          Joshi. A study by the School of Public Health at Fudan University in China, for instance, found that particles in the air measuring between 0.25 to 0.5 microns in diametre had a closer relationship to human health, especially an increased   risk    of           cardiovascular       diseases. Monitoring of PM 1 levels can help the government address the major source of pollution. Unlike PM10 (coarse pollution particles) which can go up due to dust, PM1 is entirely because of combustion. "The major contributor to PM1 is from the   transport           sector, particularly          diesel vehicles,"    said   Beig. "There have been studies in the UK that found 90% of diesel emissions to be PM1 particles. It's not surprising to find high PM1 levels even in cleaner areas because these cannot be seen and they don't collect together like the bigger particles. Such tiny particles cannot occur naturally in the environment. They are most likely from traffic sources," said Roychowdhury, who heads CSE's clean air campaign.

The PM 1 particles are so light that now for vehicles with Euro 5 fuel standard, the emission is being counted in number of pollution particles as   against        the     weight         of       particles. A study by Indian Institute of Technology (IIT) Kanpur published in 2010 also found similar concentrations of PM1 in Kanpur. They found PM1 levels to be between 30 to 13 micrograms per cubic metres in the monsoon season.

Another study conducted in Hong Kong by the School of Human Settlements and Civil Engineering, Xi'an Jiaotong University and other universities, found vehicle exhaust was the largest contributor to PM1 (38%), followed by secondary aerosols (22%), waste incinerator/biomass burning emissions (16%), residual oil combustion (12%), industrial exhaust (7%) and re-suspended road dust (5%). Annual average PM1 concentrations in 2005 when the study was conducted ranged from 44.5 to   19.5   micrograms per     cubic meters. PM1 is not being monitored widely like PM10 or PM 2.5 particles. SAFAR plans to set up another PM1 monitor at a more busy location in Delhi.

 

Refernce:  Times of India