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Measuring air quality will soon be only a click away

A Beijing-based air pollution activist is developing an app that can generate air quality measurements from a photograph.

health Updated: Jun 06, 2017 11:51 IST
China’s Zou Yi , who is capturing Beijing’s air pollution by taking photos of the city’s skyline everyday for the past 3 years.
China’s Zou Yi , who is capturing Beijing’s air pollution by taking photos of the city’s skyline everyday for the past 3 years.(HT Photo)

Beijing: Zou Yi remembers the day clearly, December 1, 2015. A thick smog had enveloped Beijing city. He took a photograph and posted it on WeChat, China’s version Facebook. It received 130 million hits.

“There was so much smog, you couldn’t do anything, you could not see anything,” he recounted, sitting at a Beijing café.

The smog that persisted for days was the worst the city had seen in many years and even the authorities could not turn a blind eye. For the first time, the Chinese government declared a ‘Red Alert’ because of the dangerous levels of air pollution.

The photograph that Yi took that smoggy day in December was just one of thousands that he has taken over 4 years. Every day since 2013 he has taken a snap of the Beijing TV Centre building from the window of his 13th floor apartment. He posts a photograph of his morning view on China’s social media platforms Wechat and Weibo daily.

“It is a record, to raise awareness about air quality,” he said. Yi left a career as an engineer working in many conflict-ridden parts of the world from Pakistan to Liberia, to devote himself full-time to the task of documenting Beijing’s struggle with poor air quality. “I have to find the truth, to present the facts.”

The snaps of the Beijing TV Centre are an immensely valuable resource for anyone studying air pollution because it provides an unbroken record of pollution from the same spot. Though Yi only posts atleast one photograph a day, he takes around 200-300 photographs from different parts of the city and has built a repository of over 400,000 photos from Beijing.

Not content with merely documenting the air pollution problem Yi decided to use his archive for an even more ambitious project. Two years ago he conceived the idea for a mobile application for analysing air quality based on photographs.

The tool applies deep learning techniques, overlaying images taken by Yi over the years with actual air pollution data for the particular day, which helps the software read any image for air quality information. Users can take a snap on the app and get instantaneous air quality measurements. For now, it analyses the images for PM 2.5 (particulate matter that is 2.5 microns or less in size) levels that is one of the most insidious kinds of air pollutants.

A Global Burden of Disease study estimated that 1.6 million people died in China in 2015 from outdoor air pollution-related health impacts. In India, the number is 1.1 million.

“India now approaches China in the number of deaths attributable to PM2.5,” said the report by the Health Effects Institute and the Institute for Health Metrics and Evaluation.

On a recent afternoon, Yi held up his phone to capture a highrise in north Beijing, generating readings that he then compared with the government’s air quality data for that day. The values of the official data for PM 2.5 concentration were significantly lower.

For the longest time, the Chinese government did not make air quality data easily available to the public. In 2008, the American embassy in Beijing started to release air quality measurements from their own rooftop air-quality monitor. It was aimed at Americans living in the city but the air quality tweets went out every hour, ruffling Beijing residents.

In a tweet from November 19, 2010, the U.S. embassy termed the air quality in Chinese capital “crazy bad,” it had shot outside bounds of the air quality index that U.S. Environment Protection Agency prescribes. By then there was already a growing awareness among Chinese citizens demanding that the government at least acknowledge the problem and do something about it.

In the initial years, the Chinese government data vastly varied from U.S. embassy dispatches leading the public to wonder if they were being misled. Yi said that these days the measurements from the government are mostly in line with the American embassy. But issues still remain.

A long-standing debate around air pollution monitoring has to do with the location of monitoring stations. Yi believes air pollution should be measured in places where it affects people the most; in heavily populated city centres and residential areas rather than far corners of cities and towns.

At a conference earlier this year an official from the Central Pollution Control Board, India’s apex pollution regulator, suggested that media discussions about Delhi’s air pollution were biased because they quoted readings from monitoring stations in the worst-polluted areas. The placement of the monitors can actually also present a rosy picture. Yi explained how the discrepancy in his readings and the official air quality data could be explained by the fact that the Chinese government’s monitoring station could be located in a leafy park, where air quality was likely to be better.

His method of capturing air pollution data puts the power literally in people’s hands. They can capture air pollution at any spot by clicking a photograph.

About 6 months ago Yi launched Beijing AirNow, a non-governmental organisation, which works with scientists across the world. The photo- documentation initiative that he started in Beijing has now expanded to 20 Chinese cities and 7 international cities with the help of volunteers and collaborators. New Delhi is not one of the cities on the list yet, but Yi is keen to reach out to potential partners in India’s capital.

The software is still undergoing validation, but he hopes to release it for the public in a few months. He will distribute it free he said because it is a public service for him. While he wants millions of people across the world to make use of his app the real intended beneficiaries are somewhat closer home. “I am doing this not for myself but for my children,” he said.