Wikipedia:Reference desk/Archives/Science/2023 June 26

= 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)
 * Might it depend on where they take the respective readings? ←Baseball Bugs What's up, Doc? carrots→ 02:06, 26 June 2023 (UTC)
 * 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&#x1d122;&#x1d106;&#x1D110;&#x1d107; 02:29, 26 June 2023 (UTC)
 * 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)
 * 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)
 * 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)