Saturday, August 14, 2021

Smoke, Round Two

 

We've had the (un)fortunate opportunity to test out the sensors again, during an official heat wave + air quality warning notice. This time, I wanted to compare the indoor and outdoor quality with the presence of an air filter. The tests started with the two sensors moved over from my parents' place and left inside our apartment for a few hours. The first data point was soon after throwing the one sensor onto the balcony, while the other one was placed inside.

Based on the measurements, it looks like the worst of it only spanned Friday during the day and the early parts of Saturday morning:



Beyond the general trend over August 13-14, this data seems to suggest is that:

a.) indoor air quality is better
b.) indoor air quality tracks the outdoor one, to some extent despite the filtration

The obvious questions that I'd like to ask based on this include:

- would swapping the two sensors have yielded similar results?
- assuming the sensors at least track the levels somewhat consistently, how much of the indoor air quality improvement is due to the active filtration?

At some point another neat test would be to sample at higher intervals around the kitchen to see the effect of cooking, coffee roasting, etc. So far, I can also see that cooking has a pretty significant effect:


This was with the balcony doors closed, and you can see the HUGE spike at around 8 in the morning caused by cooking on the stove, even with the vent hood going! At least it came back down quite fast...






Tuesday, August 03, 2021

Air Quality History - Comparison with external data sources

 So after logging data for a few days, and having experienced a spike two days ago, we see the following:

(note I have not correctly implemented the breakpoint yet for the 50-100 level for the 2.5 AQI number, but the trend is there)


Compared with aqicn.org''s chart at the YVR location over the same period:


What I've noticed however is that there's quite a big difference between stations, at least when the entire city is not completely enveloped in visible smoke. Therefore, any discrepancy, especially when the values are generally low, could be quite localized.

The test google drive spreadsheet is getting a bit long... I'm contemplating either being lazy and just starting a new one (since by default it just tries to write to "Sheet1"), or maybe code up something more interesting...

The other thing of interest is that the aqicn hardware platform uses data tha comes from these Plantower PM5003/7003 sensors, which are in the similar price range of the SDS011 and have very similar performance characteristics. They also have a nice list of similar devices here. Is it time for another AliExpress order?