What happened when China provided its cities with real-time pollution data

Smog covers the Chinese city of Harbin in January 2019. China deployed a massive network of air quality monitors in 2013, and a new study finds that this pollution data has improved awareness and health outcomes. (Image: Tao Zhang/Getty Images)

A new study finds that, in 2013 at least, China went about urban data collection the right way — and people reaped big benefits.

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A few years ago, China deployed a nationwide monitoring program across hundreds of cities, blanketing virtually its entire population. Seen through the lens of recent news, that sounds terrifying. But the purpose of this monitoring network was to collect and publish real-time air-quality data, and according to a new working paper by a team of economists — including Panle Jia Barwick of Cornell University, who’s been studying Chinese pollution for years — the social benefits were quite large.

Of course, one good use of technology doesn’t make up for a bad one, but the analysis reminds us that urban data collection is too broad to be labeled helpful or harmful without a view of the details. As more and more cities adopt digital tools, the exact purpose and usage is what matters most. A responsible tool, applied to a real problem, can directly improve people’s lives.

Now, for that view of the details:

PM2.5 is the term for tiny particulate matter, with a diameter of just 2.5 micro-meters, found in air pollution. It’s been implicated in any number of serious health problems, from asthma to respiratory disease to premature death. Studies have found a clear connection between exposure to PM2.5 and decreased life span. Urban areas can have particularly high PM2.5 rates given their high volume of vehicle traffic — a key source of it.

So PM2.5 is not good, and China’s initial handling of it wasn’t good, either. During the 2000s, China’s average daily concentration of PM2.5 was five times above the levels deemed safe by the World Health Organization.

To make matters worse, at that time, the national government didn’t share much information on pollution. Chinese cities did release a daily air pollution index, but it didn’t incorporate PM2.5 and it didn’t inform mass media broadcasts. In fact, government and media alike often characterized smog as fog. For example, November 27, 2011, newspaper headlines blamed dense fog for major flight delays, when in fact satellites show extreme pollution. As one journalist later wrote: “We all believed that it was fog back then. That’s what we called it.”

Facing pressure in 2012, China finally recognized PM2.5 as a major pollutant, and created new standards around it. It then rolled out a sweeping national air-quality program to monitor several major air pollutants (including PM2.5) over the course of just two years. All told, the program installed some 1,400 monitoring stations across 337 cities, covering roughly 98 percent of the population.

To enhance awareness of this data, the program published the information on an official website. Importantly, it made the data publicly accessible, allowing third parties to incorporate the data into apps or other pollution tools.

The research team of Panle Jia Barwick and collaborators took advantage of this natural experiment to study people’s behavior before and after the launch of the air-quality network. In the new working paper, they call this study “the first empirical estimate of the value of a nation-wide program on pollution monitoring and disclosure.”

The first thing they found was clear evidence of heightened public awareness about pollution levels. Articles related to air pollution in the state-run People’s Daily went from an average of less than once a week to almost daily. Mobile phone apps about pollution surged by 500 percent after 2013, four times faster than growth of other apps. By 2014, the Guardian reported that China’s air quality index had became a subject of “daily talk”:

Air-quality apps are the staple of every smartphone. Chinese micro blogs and parenting forums are monopolized by discussions about the best air filters (sales of the top brands have tripled over the last year alone) and chatter about holidays to “clean-air destinations.”

Since 2013, Chinese apps released in the Apple Store related to pollution (blue) have significantly outpaced those released in other categories (grey). The spike is even more striking when considering that prior to 2013, “pollution” apps typically streamed weather information, not air quality data. (Image via Barwick et al, NBER, 2019)

Suffice it to say, word got out, and the newly empowered public responded accordingly. The research team found evidence of clear behavioral changes in several areas of life, demonstrating the power of real-time information to impact both short- and long-term decisions:

Air purifier purchases. Within a year of a city implementing air-quality monitors as part of the program, air purifier purchases more than doubled — “rising from 11,000 units per month in 2012 to over 25,000 units per month after 2013,” write to the researchers.

Trip avoidance. Buying an air purifier is a blunt response to pollution, but the information program led to more nuanced decisions as well. Using retail purchase data, the research team found that when air pollution levels were higher, people made fewer “deferrable” consumer trips (things like grocery shopping or dining at an outdoor restaurant) — even as they continued to make “essential” trips that couldn’t be postponed (such as doctor visits). In contrast, consumer trips didn’t vary with pollution levels at all before the air-quality program’s installation, nor did the researchers find any effect in neighboring cities that didn’t yet have monitoring. In other words, the data made the difference.

Home buying. Pollution information impacted major long-term decisions as well as daily ones. The researchers found that, after the information program was deployed, increases in pollution of one standard deviation were connected with a 4–6 percent reduction in home prices, compared with no statistical relationship in an area before deployment. “In other words,” they write, “air quality is capitalized in housing prices.” When people know an area is highly polluted, they don’t want to live there, and the value of homes fall accordingly.

Over time, all the pollution apps and air-quality data contributed to a healthier population. Using national mortality data in 131 cities, from 2011 to 2015, the researchers found a post-program decline in health problems related to cardio-respiratory causes, with an even greater impact in more urban areas. They calculate a 7 percent reduction in premature deaths attributable to air pollution thanks to the program, largely the result of people simply choosing not to go outside on super smoggy days.

There are some massive economic benefits as well. The researchers estimate that this impact ranges from 130 billion renminbi ($18.9 billion USD) to 520 billion renminbi ($75.5 billion USD) annually, based on how one chooses to measure the value of things like productivity, health conditions, and a longer life. Even at the low end of the scale, that benefit far outpaces the operating cost of the program, which comes to 20 billion renminbi annually ($2.9 billion USD). The researchers conclude in summary:

Based on several rich and unique data sets, our analysis provides strong evidence that the pollution monitoring and disclosure program has led to a cascade of changes such as increased pollution access and awareness, more pronounced short- and long-term avoidance behavior, as well as muted pollution-health relationship. The findings suggest that the value of the information monitoring and disclosure program arising from improved health is at least one order of magnitude larger than its cost.

A few caveats bear mention. The biggest, of course, is that pollution information — even when it’s made widely accessible in real time — is no substitute for actually reducing pollution itself. Nor does the study paper make clear whether or not the monitoring stations are used for other, less beneficial means.

Some others: Health outcomes are highly complex, and rarely the result of just a single behavior. Some of the health improvements likely reflect actual pollution reductions, not just avoidance of pollution. While the researchers believe they’ve controlled for complicating factors, direct causation is always difficult to ascertain in large-scale population studies. And information is not the only factor in decision-making.

Still, overall, the program seems like a great success. The study authors tout the value of investing in pollution information networks for developing countries, but the truth is even the U.S. could stand to benefit from better air quality data. After years of decline, PM2.5 is rising again in the U.S. — a troubling trend fueled partly by the current administration — leading to an estimated 9,700 additional premature deaths in 2018. Meanwhile, only one in five U.S. counties actually have a PM2.5 monitor.

This is a problem that responsible approaches to urban data collection can help, as long as we remember that urban-tech can be harnessed for good, even as we strive to mitigate the bad.

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January 16, 2020