The Central Pollution Control Board announced this week that that New Delhi’s air is not the most polluted in the country, or even the second-most polluted. According to the latest Air Quality Index Varanasi in Uttar Pradesh and Muzaffarpur in Bihar have overtaken the national capital. A scientist with the Delhi Pollution Control Committee has also reportedly told the Delhi High Court that he thinks particulate matter levels in the city can be brought within the range of 100 to 150 micrograms per cubic meter, a big difference from current levels in the high three hundreds.

None of this is really going to make a difference to Delhi residents. According to a new report with the ministry of health, the disease burden due to air pollution won’t ease up if air quality is merely improved. Air needs to be scrubbed of particulate matter bringing it to levels as low as 35 micrograms per cubic meter to reduce the number of deaths due to air pollution.

Here’s what that imposing disease burden looks like. In 2010, household air pollution from the use of solid cooking fuels resulted in approximately 1.04 million premature deaths in India, the report says. About 6,27,000 lives were lost in the same year due to ambient air pollution, the kind caused by dirty emissions from vehicles. Household air pollution has cost Indians 31.4 million Disability-Adjusted Life Years, A measure of the total number of years lost due to disability, ill health or early death. The corresponding number of years for ambient air pollution is 17.8 million. Six years later, the disease levels seem to be as dire, say public health experts estimating disease burdens.

The formidable burden in largely due to the enormous large section of people still using solid fuels – an estimated 70%. The percentage of people actually using solid fuels has come down from almost 90% in the 2000 census to about 70% in the 2011 census. But since population growth has not decreased proportionately, the absolute numbers of people exposed to household air pollution remained relatively static, said Kalpana Balakrishnan of the department of environment health engineering at Sri Ramachandra Medical College and Research Institute in Chennai and one of the authors of the report.

Here’s a look at how the number of deaths caused from different sources of particulate matter – household air pollution (HAP), ambient air pollution (AAP), environmental tobacco smoke (ETS) and active tobacco smoking (ATS).

The fact that household pollution emerges as the biggest killer doesn’t mean that other pollution sources must be ignored, Balakrishnan stressed. It only shows it’s not just the amount of pollution emitted – think of the emissions from large power plants for example - but the exposure to sources of pollution that dictate how bad its effects will be.

“Air pollution impacts are seamless and people move in and out of these environments in very unpredictable ways. You cannot argue for public health on the basis of only one clean environment,” said Balakrishnan. “There needs to be equal amount of focus for urban and rural and for household and ambient [pollution].”

A second factor affecting the number affected by air pollution is the recognition that air pollution causes more than just bad respiratory effects in vulnerable people like children but can also cause lung cancer and cardiovascular diseases in the general population. “Whenever you have an exposure that plays on the total population and the baseline rate, then the burden becomes unmanageable and that’s the reason for the need of urgent action,” said Balakrishnan.

The number of deaths in 2010 due to lower respiratory infections in children below the age of five (Resp<5), chronic obstructive pulmonary disease (COPD), ischemic heart disease (IHD) and stroke ran into lakhs. Cancers of the trachea, bronchus and lungs claimed more than 75,000 lives.

The picture isn’t going to get any better by reducing particulate matter in the air from levels of over 300 micrograms to levels of 100 micrograms even though that is cutting pollution by half. This chart shows why.

The chart plots the risk of ischemic heart disease with increasing PM 2.5 levels ad shows that reducing exposure from 350 to 175 microgram, is not likely to reduce risk significantly. The risk of disease on falls when PM2.5 is cut to below 35 micrograms.

Think of this in terms of cigarette smoking, which is the other big generator of particulate matter. A person who cuts smoking from a pack to a couple of cigarettes a day does not reduce his disease risk. He needs to quit completely. Similarly ambient and household air pollution need to be benchmarked against levels that are adequately “clean” and not just “improved” when compared to “dirty” baseline.

So, whether Delhi, Varanasi or Muzaffarpur, the health effects of air pollution are likely to be equally severe unlesswidespread and drastic measures are taken to clean up. As Balakrishanan said, “Keeping some parts of Delhi clean or some houses clean with LPG is not clean enough. You can’t even perceive the health benefits. We have to have a critical mass of air quality action. Entire cities, entire villages, entire districts need to be transformed.”