I'm at my computer right now. It's in an upstairs office -- a converted bedroom -- in my home in Sacramento. I haven't been out of my house in a few days. I'm trapped by smoke drifting into the valley. I'm one of those "sensitive" to air pollution (I have mild asthma), so I'm pretty well stuck until our air clears.
I can see that it's smokey outside, but I also rely on the information reported by our local air quality district. I check the data on their website, Spare the Air, regularly. I'm most interested in the information about the tiny, tiny particles that can cause the biggest problems, particulate matter that measures less than 2.5 micrometers in diameter, or PM2.5. Spare the Air tells me that there are only a few monitoring stations in my area for this particulate matter, but one's not far from me.
About 3pm yesterday, the air got visibly worse outside. We're running filtered air conditioners and a very high-end air filtration unit in our home, yet I could actually smell smoke. I checked the Spare the Air site for current data on PM2.5 and it reported 309 -- in the "very unhealthy" range, for everyone -- for the monitoring station closest to me. This figure was also recorded in the column for the highest reading in the prior 24 hours.
Later that afternoon, the data for my monitoring station went blank. Where data was reported for other stations, the Sacramento - Del Paso Manor station data was empty. Then the whole site went unavailable for a while.
When the site came online again, the 309 data was missing.
I checked the 24-hour historical data. Gone.
Actually, it wasn't just gone -- it was CHANGED.
Where it had reported the PM2.5 levels as 309, it had been changed to 160, just about half the level of pollution it reported previously.
At first, I thought maybe I was imagining things. I found a link to email the Spare the Air people and sent them and email asking if I'd seen things correctly earlier. No response.
But then I recalled how I went around and announced to my family how sucky the air was. My husband was working on something outside and I told him he needed to come in because of the unhealthy pollution levels. I didn't imagine it.
This morning, I phoned the Sacramento Air Quality Management Districtto ask where the 309 figure went. I was connected with a guy who answered his phone, "Communications." I don't recall his name.
He confirmed that the reading for 3pm had, in fact, been 309. I asked him where that number had gone. He told me that they'd had their web server slammed because of unprecedented traffic, and that had an impact on their site.
I said, sure, but the data is different; the server being very busy won't change the database.
He also told me that the Spare the Air site is run by meteorologists, and that the server is also connected with one or more EPA websites.
Then he said that they had a "number of issues" they were trying to get "fixed", and the incorrect 3pm data was one of them.
And THEN he pointed out the asterisked disclaimer on the data reporting page, "*Preliminary data, subject to revision or deletion."
Basically, I got nowhere with my query, where did the actual 3pm data go, and why? More importantly, why was the data changed?
My husband is a database expert, and he tells me that the server being overtrafficked would cause data to show up blank, but not for the data to be changed. And all of the data should have shown up blank, not just the data for the one reporting station.
Interestingly, two pollution monitors in nearby Placer County "both mysteriously stopped running Sunday when the air was at very unhealthy levels." Coincidence?
I still want to know where the data I saw went and why it was changed. If it was changed, who changed it? Who would benefit from the air pollution being reported as basically half its actual level?
UPDATE: Info on who owns what site, very interesting:
[slurped from my comment below, since it really belongs here as an update]
(courtesy of techie husband) because that appears to be where the dodgy stuff is going on, at least initially:
Apparently local site sparetheair.com has the same IP address as national site airnowdata.org.
Registration information for airnowdata.org shows that it's registered to a private company (!) called Sonoma Technologies.
Cursory poking around the airnowdata site shows overlap with the EPA.
Updated update!
Check THIS out:
airnowdata site page -- Whaaaaa???? And who is LADCO?
Update, again:
I got a response from Communications Guy:
We spoke earlier in regards to your email. I was able to track down an answer for you. The bar charts that you are seeing like this one here,
http://www.sparetheair.com/...
does not reflect the high reading because these numbers are the 24 hour averages that run from 4 am to 4 pm. So even if the monitors trigger a 309 like they did yesterday, the hour reading on the chart are averaged out over 24 hours. I hope this helps.
So, this means the data is smoothed to conform to the rest of the data? Is that correct? Anyone know?