Science desk
< June 25	<< May \| June \| Jul >>	June 27 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

June 26

Air Quality Index differs widely by source

At thiS moment in Manhattan, AccuWeather places the PM2.5 reading at 32, Weather.com 65. What's the point of AQI if it differs so much by source? 68.174.155.22 (talk) 01:12, 26 June 2023 (UTC)[reply]

Might it depend on where they take the respective readings? ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:06, 26 June 2023 (UTC)[reply]

Yep. Where in Manhattan are they taking the readings? W. 36th St. says 80. W. 61st says 59. Precise location matters (for example, is there construction happening near one of them?) My own monitor is often 25 points different from my friend's less than a mile away. AQI is a rough guide to air quality, not a precision measurement. --jpgordon^{𝄢𝄆𝄐𝄇} 02:29, 26 June 2023 (UTC)[reply]

Yes, it's all about location. There is an EPA monitoring station near where I live here in Australia. Two houses immediately across the road used wood fires for heating, and my suburb routinely scored close to the worst for air quality in our broader city area. Both those houses have now changed to electric heating, and suddenly we're near the top of the clean air ladder. It's silly. HiLo48 (talk) 03:58, 26 June 2023 (UTC)[reply]

It's even further complicated, actually. Different services (commercial, agency, and research) aggregate different subsets of monitors, and use different periods of time for arriving at normalized figures. They aren't even completely consistent about which types of sample constituents are fed into particular readings, nor is the equipment by any means standardized and consistently calibrated in terms of thresholds. It's a very complex (and, for the present at least, highly non-harmonized) system--or more accurately, set of systems. OP, I have a bunch of resources for parsing this stuff and will try to find time in the next couple of days to relay it to you here: if I forget, please ping me or drop a note on my talk page. SnowRise ^{let's rap} 11:18, 29 June 2023 (UTC)[reply]

Thank you in advance. I'll drop you a note on your talk page as well. 68.174.155.22 (talk) 01:33, 4 July 2023 (UTC)[reply]