PM2.5 Levels Are Not 16 Times Higher in the Subway (They Are Only About 5 Times Higher)

From the News Briefs We Don't Really Wanna Hear department: Environmental experts responding to recent online discussions about their report stating the air in Beijing's subway system is 16 times worse than the air outdoors is not true ... because heck that was only one day's test and not enough to reach a scientific conclusion.

The official, from an NGO called the Green Beagle Environment Institute, did not deny their tests indicated readings 16 times worse than outdoors, but said it was inaccurate to take one day's readings and extrapolate them to say that the air is always that bad in the subway. 

Intrepid journos at Beijing Youth Daily then went out and replicated the tests on Tuesday only to find that the air was not 16 times worse than outside, merely about 5 times as bad.

The Youth Daily folks tested the air in three stations, taking readings at the subway entrace, at the turnstyles, on the station platform and in the subway car itself. The average readings indicated the air was worst on the platforms (8.3 times worse than outdoors); followed by inside the train cars themselves (3.3 times worse) and at the turnstyles (2.4 times worse). Averaging all their subway readings with the ones taken at the entrance outside indicated an overall average reading of about 4.6 times worse. 

Granted, the Beiing Youth Daily tests were equally unscientific in that they were based on one day's readings, but you're starting to see a trend here: the air in the subway is worse than outside.

So if the prospect of being crammed into a subway car nose-to-nose with a random sample of various and sundry wintertime snifflers and sneezers is not enough to convince you to wear a mask on the subway, let the signficantly worse air quaility push you over the edge towards donning a little something to make your subway trip a little healthier. Or maybe consider the bus? At least they have Wi-Fi.

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I asked the same on their Facebook but no answer.

Measured in my gym at a day it was AQI 500. Got the value 1600 on my meter when outside it showed 16000! on the pm 2.5 scale.

In my apartment I had 100-150 with purifiers on.

My gym is located underground -1 floor.
Many people, heat, movement etc will affect the meter

Will do a test today when the air is good

^ I'm curious about that too -- I'm gonna try next time the air is bad

 

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So the air is consistently worse, even on grim 400+ days, or the air in the subway is dirty at a fairly stable level and only registers dirtier than the outside air during clear days?