Tuesday, August 21, 2018

Too many apples-to-oranges comparisons with Beijing

"Our air is worse than Beijing"
"This is the worst air quality in the world"

Some variant of these claims have been repeated in the past few days. Are they true? Lets make an apples-to-apples comparison and find out.

If we compare conditions across the world right now, then WA probably has the ignoble distinction of being one of the most polluted places. Here's the global AQ map as of 1PM PDT:

Colors are AQI colors (see legend in plot below). South and east Asia are seeing a lot of reds and maroons, which means a lot of people are exposed to Unhealthy or worse air at this point in time. Washington is in the same abyss, air quality wise. Not good.

Now lets see how air quality at a few WA sites compare with normal patterns seen in Beijing and New Delhi year round. Data from those cities are were obtained from air quality monitors at the respective US Embassies, which routinely record very high PM2.5 concentrations. I've defined "normal" as the range between monthly lower and upper quartiles, since the median passes right in the middle of it. This is also known as the interquartile range, or IQR.
The above figure shows how air quality in Seattle, Spokane and Omak have varied from 1 Jan- 20 August 2018, against the backdrop of monthly IQRs in Beijing and Delhi. As can be seen, the latter cities experience terribly compromised air quality primarily in the winter months. And its MUCH worse than what we experience, even during wildfire season. Even though Omak spiked right to the top of Delhi's IQR a few days ago, bear in mind that:

  1. Delhi's concentrations are higher than it's own IQRs 25% of the time. Or put another way, Delhi records concentrations higher than Omak's spike, for 3 months of the year.
  2. Omak's air is unlikely to remain "Hazardous" for several months. 

In spite of our wintertime temperature inversions and woodsmoke concerns, we're still in far better shape at that time of year.

So stacking the relatively "clean" season in Beijing/ Delhi against our "dirtiest" season is not a proper comparison.

Nevertheless, wildfire smoke- even of relatively short duration- still affects the health of a lot of people. This blog, even the article just below, contains a lot of resources on steps that can be taken to minimize its harmful effects.

13 comments:

  1. What happened to the "webcams" tab on the Smokeblog home page?

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    1. You can see the WSDOT webcams by clicking on the map layers and selecting it from the dropdown list

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    2. Nice to know someone was looking at them, Pete! We removed them to make room for the Spanish tab, but I just put 'em back. Refresh your page. They should be there now.

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  2. These wildfire seasons are very good opportunities to simulate living in more polluted areas of the globe without having to leave the comfort of your yard. When I close my eyes, I'm quickly reminded of my visits to India or China.

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  3. Well-- yes, there are plenty of places with terrible air more often. However they also have shorter life spans, chronic illnesses and other poor health metrics-- so just because we 'don't have it as bad' is not something to feel good about. It's not a contest about who has it worst-- any humans having to breathe polluted air is unfortunate.

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    1. This post was to highlight poor data comparisons that are being made, not to trivialize anyone's breathing problems. The last paragraph of the article acknowleges this and points to health protection resources.

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    2. Yes sorry, truly appreciate all you staff are doing! Commented more in case folks aren't taking it seriously, many I know are blowing it off and going about normal routines because they don't see the acute symptoms and perhaps lack awareness of the serious long term risks. Your post was informative and interesting. Thank you. I check this blog all the time during smoke events, thanks again. And I've been to Beijing and other places.. and often come back congested/ill.

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  4. Just wanted to say thanks or all of your good information- we are relying on it during this wildfire season

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  5. Thanks for the good information it is appreciated!

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  6. Thanks for the info. I am sure that other like me that have asthma appreciate the work your doing. Keep it up and let’s hope the smoke clears some soon

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  7. Great Job, Mr. Dhammapala!

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