While the Delhi Pollution Control Committee (DPCC) and the Delhi government, in the past, has claimed that dubbing the city as one with the worst air is “unfair”, the CSE study has found that this could be correct. Exposure levels for those using public transport is over 2-4 times higher than the background pollution level reported by the DPCC.

“The ambient or the background pollution level reported by DPCC are in essence the pollution levels over a large spread. But in this study, we are looking at points where people are exposed to extremely high levels of pollution from very close proximity,” Anumita Roychowdhury, CSE’s executive director-research, said.

The study has found that those travelling by open modes of transport such as auto-rickshaws and cycling, apart from pedestrians, have the highest exposure. In the case of Metro, while the sealed environment in the underground stretches shows lower levels of pollution, the overhead tracks have higher exposure levels.

Not surprisingly, pollution levels peak near junctions and during traffic snarls. For instance, in a jam on a stretch close to Paharganj, PM 2.5 levels peaked at 1,170 microgram per per cubic metre. The standard level for PM 2.5 is 60 microgram per cu m. Exposure also increases on routes where proximity to diesel trucks is higher, the study said.

The study has also found that travelling in cars doesn’t reduce exposure to pollutants significantly. Monitoring during off-peak hours found that the average levels were double the ambient levels, several times higher than the prescribed norms.

CSE used a dust truck aerosol monitor to measure both mass and size fraction of particulate matter. The study includes real-time monitoring carried out in different modes of mass transportation during morning and evening peak hours in the first two weeks of February. The average exposure was compared with the background ambient levels monitored by the DPCC at the nearest monitoring station.

“Measuring exposure is important, because it takes into account the health impact of particulate matter and other pollutants on people while they are travelling. It’s when the people of Delhi are on the road that they are at maximum risk,” Roychowdhury said.

Traffic Police have to hold their breath

The CSE study has found that traffic police personnel are exposed to “unacceptably high levels” of pollution. Monitoring carried out at the ITO crossing showed peak exposure to be eight times higher than the ambient level. It found that traffic police personnel were exposed to levels ranging from 400 to 800 microgram per cu m.