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To cut Delhi’s air pollution, pinpoint the source

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By Eric Dodge & Rohini Pande

This winter, Delhi’s government and the judiciary have implemented several policies aimed at cutting the national capital’s air pollution. The just-concluded odd-even scheme in the city required motorists to find alternative means of transportation every other day.

Car-free days, first in Gurgaon and then in Delhi, appeared to cause a temporary dip in pollution levels. The night hours when trucks can pass through Delhi have been reduced, and the National Green Tribunal has issued a direction to lower truck traffic coming into the city at night by levying an additional entrance fee.

On some days the air may be clearer. But what remains hazy is where Delhi’s air pollution comes from. Over the years, multiple attempts to find out – called source apportionment studies – have yielded contradictory results. There are numerous suspects: cars and trucks, smokestacks, farm fires in Punjab and Haryana, and dust from construction sites to name just a few. Without a better knowledge of the portion contributed by different sources, any policy response, no matter how bold, will be a little like a blind attempt to pin the tail on the donkey.

But that may be changing. The Indian Institute of Technology-Kanpur (IIT-K) has now released a major study, commissioned by the Delhi environment department in 2011. This promises to give the clearest picture of source apportionment yet. And other new sources of quality information on air pollution are appearing: the government has plans to add 10 new air quality monitoring stations in Delhi, and news outlets are setting up their own monitoring systems, including IndiaSpend #Breathe.

This could be a turning point in our understanding of the sources of Delhi’s deadly air, as well as our ability to craft smart policies that shut them down. We at Evidence for Policy Design (EPoD) are researchers who assist government ministries in formulating such responses. We think that at a time like this – a critical convergence of public concern, policymaker attention, and academic contribution – it’s worth taking stock of what we know now and how we came to know it. That clarity will make it easier to guide the discussion toward a policy response that will stick.

There are two ways of conducting source apportionment studies: direct sampling based on chemical analysis, and secondary data analysis based on monitoring data. The international best practice is to rely on receptor-based studies, but where budgetary constraints inhibit adequate sampling, analysis using secondary data may dominate.

Over the past 10 years, and excluding the just completed IIT-K study, we count 15 source apportionment studies that sought to pinpoint the sources of emissions and their respective contributions to Delhi’s overall air pollution. Ten are based on direct sampling; the other five rely on secondary data. While the main sources identified are similar across studies, the relative weights placed on different sources by these studies vary dramatically. This underscores both the difficulty of conducting them and the wide range in the quality of the studies currently available.

Getting a reliable picture of air pollution is inherently difficult due to Delhi’s changing weather conditions and constantly shifting patterns of emissions throughout the day, week, and year. Moreover, some of the most important pollution sources lie outside the National Capital Region. This makes it important that direct air sampling studies are broad enough to capture multiple sources and take samples at several different time points. An inability to do this-largely due to budgetary considerations-and the resulting differences in what gets sampled are an important part of the explanation for the large differences across studies.

In such situations, secondary data-based analysis may well be the best option for source apportionment studies, as long as these secondary sources are reliable and span relevant emission sources. Right now, we lack a measure of whether that is the case. Without standardized best practices about which secondary data sources to use and which model to use, source apportionment studies will continue to give conflicting results going forward.

So, we not only lack the best information on pollution, we also lack consensus on how to determine the second best. (IANS/IndiaSpend.org) (Photo: social.yourstory.com)

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Air Pollution: WHO Releases List of The Best And Worst Cities

90% of world's population breathes badly polluted air: WHO

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Air Pollution
WHO releases a list of most and least polluted cities. Pixabay

Nine out of every 10 people on the planet breathe air that contains high levels of pollutants and kills seven million people each year, according to a new World Health Organization (WHO) study released on Wednesday.

The study is an analysis of what the WHO says is the world’s most comprehensive database on ambient air pollution. The organisation collected the data from more than 4,300 cities and 108 countries, reports CNN.

People in Asia and Africa face the biggest problems, according to the study.

More than 90 per cent of air pollution-related deaths happen there, but cities in the Americas, Europe and the Eastern Mediterranean also have air pollution levels that are beyond what the WHO considers healthy.

The new WHO data show that US cities on the more polluted side of the list include Los Angeles, Bakersfield and Fresno, California; Indianapolis; and the Elkhart-Goshen area of Indiana.

Air Pollution.
Air Pollution. Pixabay

Peshawar and Rawalpindi in Pakistan, have some of the highest particulate air pollution levels in the database. Varanasi and Kanpur in India; Cairo; and Al Jubail, Saudi Arabia, also show higher levels.

“I’m afraid what is dramatic is that air pollution levels still remain at dangerously high levels in many parts of the world,” CNN quoted Maria Neira, director of the WHO’s Department of Public Health, Environmental and Social Determinants of Health, as saying.

“No doubt that air pollution represents today not only the biggest environmental risk for health, but I will clearly say that this is a major, major challenge for public health at the moment and probably one of the biggest ones we are contemplating.”

Particle pollution, a mix of solid and liquid droplets in the air, can get sucked into and embedded deep in your lungs when you breathe. That can lead to health conditions including asthma, lung cancer, heart disease, stroke and chronic obstructive pulmonary disorder (COPD), according to the study.

Also Read: Air Pollution And Its Effects On Our Health

These outdoor particulates — including sulphate, nitrates and black carbon — are largely created by car and truck traffic, manufacturing, power plants and farming. In total, air pollution caused about 4.2 million deaths in 2016, it added.

“Many of the world’s megacities exceed WHO’s guideline levels for air quality by more than five times, representing a major risk to people’s health,” Neira said. This is “a very dramatic problem that we are facing now”.

Cleaner air accounts for in cities like like Wenden, Arizona (population 2,882), or Cheyenne, Wyoming (population 64,019).

The Eureka-Arcata-Fortuna area of California; Battlement Mesa, Colorado; Wasilla, Alaska; Gillette, Wyoming; and Kapaa, Hawaii, are all on the cleaner-air list.

One of the bigger US cities with cleaner air is Honolulu, according to the WHO data.  (IANS)

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