Air pollution levels got so bad in Beijing on Saturday that people were staying inside their homes, and according to the New York Times, Twitter users were calling it "beyond belief", "terrifying" and (my favourite) "postapocalyptic".
The Air Quality Index (AQI) reading was reported by the U.S. Embassy @BeijingAir Twitter feed, which posts hourly, noting the dominant pollutant, the pollutant concentration (in μg/m³, or microgram per cubic meter), the AQI value, and then a description of the AQI category. Since January 2nd, except for a few brief respites of "Moderate" air quality, the feed has been reporting at least "Unhealthy" levels of 'Fine Particulate Matter', with several long stretches of "Very Unhealthy" and "Hazardous" levels.
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Conditions got even worse going into the weekend, as the feed consistently reported "Hazardous" air quality starting Thursday afternoon, and went "Beyond Index" on Saturday afternoon, peaking at an AQI value of 755 at 8pm! Comments on the twitter feed ranged from disbelief and questions about typos, to "We've gone beyond crazy bad" — in reference to a 2010 post on the feed that called a value of just over the AQI limit of 500 "Crazy Bad" (a post that was subsequently deleted, I might add).
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Here in Ontario, fine particulate matter concentrations over 90 μg/m³ on a 3-hour running average rank as "Very Poor" on the province's Air Quality Index. When levels here reach that bad, it can send nearly anyone who is outside for an extended period of time to the emergency room.
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Taking a stroll in Beijing last Saturday afternoon — when pollution concentrations were likely well over 1000 μg/m³ when translated to Ontario's 3-hour running average — must have been like going on a walk through a burning building, where the only safe way to breath is by carrying around a heavy tank of air on your back!