Foul air a slow poison for Delhi lungs round the yrs

People in Delhi were exposed last year to pollution levels 11 times higher than what is considered safe by the World Health Organization, an analysis of average PM2.5 particle concentrations showed, suggesting the crisis was not limited only to prewinter months when the levels reach concentrations up to 45 times as high as the global standards and become a talking point.

According to Central Pollution Control Board (CPCB) data, Delhi’s annual average PM 2.5 (particulate matter of 2.5 micron size) last year was 115 microgram per cubic metre while the WHO recommends this be kept under 10 micrograms per cubic metre.

PM2.5 are ultra-fine particles roughly 3% of the diameter of an average human hair and lead to the most harmful of health effects, including respiratory distress and cardiovascular conditions, that have been linked to millions of premature deaths around the world every year.

“The WHO guideline is 10 micrograms per cubic metres for a reason. The levels we are recording round the year are not safe at all. That needs to be understood by policymakers,” Sagnik Dey, associate professor at IIT Delhi.

Till November 14 this year, the average is 97.7 micrograms per cubic metre based on data from the CPCB’s continuous monitoring stations. This cannot be compared with the CPCB’s average for last year because it may not have considered the same number of stations to calculate the average. The chronic health effects begin at annual mean concentrations are as low as 11-15 micrograms per cubic metre, according to the WHO’s air quality guideline document.

Each time there is a severe spike in air pollution level as has been for the last couple of days when PM 2.5 concentrations ranged from 250 to 450 micrograms per cubic metre.