In China, people breathe ozone-laden air two to six times more often than people in the United States, Europe, Japan, or South Korea, according to a new international study published in Environmental Science & Technology Letters . By one metric—total number of days with daily maximum average ozone values (8-hour average) greater than 70 ppb—China had twice as many high ozone days as Japan and South Korea, three times more than the United States, and six times more than Europe. Figure 3 NDGT70 Urban surface ozone level trends in China (red), Japan (purple), Europe (orange), and the United States (blue) from 1980−2017 for one ozone metric. For Japan, the EU, and the US, only urban sites with records for more than 25 years (1980−2014) are included. For China, sites in 74 major cities with continuous observations from 2013−2017 are included. The inset shows ozone trends in Beijing (red) and […]