Linda Poon is a staff writer at CityLab covering science and urban technology, including smart cities and climate change. She previously covered global health and development for NPR’s Goats and Soda blog.
A new interactive map draws data from more than 5,900 sources in nearly a thousand cities around the globe.
Worldwide, outdoor air pollution causes more than 3 million premature deaths each year. While some cities have already reached hazardous levels of air pollution—such as Delhi, India, with smog practically covering the city daily—others are coming dangerously close. This is according to a new interactive map detailing most of the world’s air quality with real-time data.
The map comes from Beijing-based environmental group Air Quality Index China, which worked with environmental protection agencies in more than 70 countries. It continuously collects data from more than 5,900 feeds coming from more than 8,000 air-quality-monitoring stations in nearly a thousand cities. Only feeds from government agencies are used, according to the website (“no DIY or amateur monitoring stations data” here). The map refreshes every 15 minutes.
Each city’s reading on the map is based on the concentration of fine particulate matter (PM 2.5) and rated on the U.S. EPA’s 0-500 Air Quality Index scale, which grades air according to how it affects public health. Studies have long linked smog to a slew of health concerns, from increased risk of heart attack to impaired cognitive development to respiratory problems.
A quick glance reveals the stark contrast between China and the United States. In China, most cities hover around the “unhealthy” zone, with some cities in the northern part of the country falling into the “very unhealthy” category. Zoom in on Beijing and you can see that for the past two days, the air quality index has fluctuated between 175 and 216.
Meanwhile in the U.S., the air quality is mostly in the “good” zone, with some southern cities falling into the yellow “moderate” category. According to the map, the city that’s recorded the worst air quality at the time of this writing is Buffalo, New York, which had an AQI of 126.
Mapping real-time updates can help officials understand how far pollution has spread from a particular city, and put adequate pollution-reducing policies in place before the air reaches “hazardous” levels.
However, the map isn’t complete. Right now, the map includes major cities in developing countries, including Delhi, India—which recorded an AQI of 317—and Sao Paulo, Brazil. But it still lacks data for much of Africa, South America, and the Middle East. That’s a problem, considering developing countries in these regions are rapidly urbanizing and starting to see dangerously high levels of air pollution.
In Nigeria, for example, as much as 94 percent of the population breathes air with pollution levels that exceed what the World Health Organization deems safe, reported Quartz. But AQICN says that it’s working to increase its coverage and aims to gather data from 10 to 20 percent more stations every year.
You can see the full interactive map here.