Pollution in Beijing spiked to the highest levels in roughly a year Thursday, marking winter’s first wave of extremely dangerous air quality, the Associated Press reports.
The U.S. embassy in the capital, which measures toxic PM2.5 pollution, recorded a high of 671 micrograms per cubic meter at 4 a.m. The World Health Organization considers 25 micrograms safe, meaning Beijing air was about 26 times the limit.
It was the first time the pollution marker topped 500 micrograms in 2014, and marked the highest level since January 2013. Air quality in the capital generally worsens in the winter when stagnant weather and a rise in coal burning exacerbate already heavy smog.