PM2.5 air quality monitor - Oregon fires

J

JBeale

Well-known member
Photo shows a T3.1 hooked up to a Plantower PMS5003 air quality particulate sensor https://aqicn.org/sensor/pms5003-7003/ and a small OLED display to graph the reading vs time. I had it inside, took it outside briefly and then back inside. When I first tested it a few months ago, the reading was about 3 to 5 units in the PM2.5 bin (it also has other size ranges).

With the current fires near Portland this evening of Sept.11 it reads around 90 indoors and 380 outside. Right now I'd say it smells like "nearby campfire". I didn't have it running yesterday when the smoke outside was far worse, like "inside a wood stove chimney". Teensy is running this code: https://github.com/jbeale1/DataAcq/blob/master/PMS5003-OLED.ino

PM25_20200911_205421.jpg
 
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I am seeing CO2 PPM counts well over 800 in Los Angeles. Normally it would be less than 500.
 
Stay safe everyone! It's "only" in the 200s here in western WA and even that is miserable. A good time to stay indoors if you can and work on those Teensy projects.
 
Happily it's cold and foggy just south of Portland right now, which is helping slow the fires. Looking at the satellite map, changing winds are pushing the brownest-looking smoke more into western WA, than OR where perhaps most of it came from. Sorry about that!
Of course PM2.5 is only one data point and the full impact of all the stuff in the air is more complicated but I'm definitely staying indoors for a while. Got some Teensies and sensor projects here to keep me occupied.
https://zoom.earth/#view=44.4,-122.44,6z/date=2020-09-12,08:50,-7/layers=fires
 
I've had a Honeywell particulate sensor connected to a T3.5 data logger for a while now. I used the PM10 data to keep track of allergens--grass pollen is a real problem here in the Willamette valley (The grass seed capital of the world!). When the smoke started getting thick, I added a serial LCD display so I could plug the system into a portable USB charger and check out the PM2.5 levels around the house.

Here's the setup:
AQLogger1.jpg

The logger also has a BME280 module to collect temperature, relative humidity and barometric pressure.

And here's what I found:
In_Out AQ.jpg

I've been spending most of the day in the computer room (my 15' x 21' home office). The filters on the furnace don't remove small particles at all, so I don't bother to run it in 'fan only' mode. I move the portable HEPA filter from the computer room into the bedroom at night and it brings the particle count down under 100 in an hour or so.
The 34.8 number in the first photo is down from the 125 found in the computer room after I moved the HEPA filter to the bedroom overnight. The PM2.5 should be down under 20 most of the day as long as I remember to keep the door closed.
 
mborgerson said:
I've been spending most of the day in the computer room (my 15' x 21' home office). The filters on the furnace don't remove small particles at all, so I don't bother to run it in 'fan only' mode. I move the portable HEPA filter from the computer room into the bedroom at night and it brings the particle count down under 100 in an hour or so. The 34.8 number in the first photo is down from the 125 found in the computer room after I moved the HEPA filter to the bedroom overnight. The PM2.5 should be down under 20 most of the day as long as I remember to keep the door closed.
Click to expand...

You show a very nice setup and some great data! Right now I'm making a portable logging setup with another Teensy and PMS5003 to compare readings at my place with my mother-in-law's. We have a HEPA filter unit on order, as do I think a lot of other people right now. It's interesting to see how much soot comes into the house even with all doors & windows closed. I sniffed around and found the inside of the dryer smelled smoky, so I guess the dryer vent is one route; no doubt the bathroom & kitchen exhaust vents too.
 
Using a T4.1 with its handy built-in SD card holder, I made a data-logging version in a cardboard box, and it went on a trip in the car to DG's ("doting grandma") place and back, and sure enough there is a reason that her eyes are watering.
SEP12-PM25.png
 
Interesting to see how things change over time, with the sensor in one location in the living room. Inside reading peaked this morning near 300 around 5 am. If I had a continuously running outside one as well, I guess I could figure out how much external airflow gets into the house.
Sep13-PM25-Indoors_Inset.jpg
 
The Honeywell HPMA115 sensor in my setup is usually within 10% of the EPA sensor about a mile away. Unfortunately, the EPA sensors seem to go off line and return "ND" at very high concentrations. I got an email response from the EPA when I questioned this. It seems that some of the sensor setups have over-limit filters at 500 that are probably there to prevent short glitches from adversely affecting the longer-term air quality index. It seems that the longer-term sensor values around 500 that we are seeing in the Willamette valley are requiring them to adjust the threshold settings.

I have also found that very high relative humidity conditions (>95%) can result in abnormally high readings. I took my sensor out in the fog yesterday morning and saw PM3.5 readings over 800!
 
A little late to the discussion, but I've used the airmon sensor and it works surprisingly well for such an inexpensive product (Japanese tech). During the wildfire smoke season when this post was originally written, here in Seattle I would use it after running a fan taped with a furnace HEPA filter with pm2.5 filters taped to the sides for the gaps (hah!) and consistently get results in the 5-10 range after I duct-taped my mail slot.
 
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