I get the outdoor data from PurpleAir. There are two stations within a few blocks of me, and they both seem to report very similar numbers, though I have not done anything to formally estimate the error/variance.
Have you thought much about circulation?
Yes, and it does seem to depend somewhat on where the sensor is placed and what the circulation is. I took notes on where it was sitting, but I haven’t tried to notice any patterns yet. I had a fan running to circulate air in the room the whole time that data was being recorded. I did not open the door very many times.
Additionally, it looks like indoor PM2.5 is tracking outdoor PM2.5. Have you thought much about other sources of ventilation?
Some, yes. I do expect the indoor PM2.5 to track it at least a little, since I would (naively, at least) expect the filtration system to work linearly (that is, it removes a percentage of particulates that is not dependent on the particulate concentration. But it does not seem to be linear, since it was removing a smaller fraction later in the day when the outdoor concentration was higher. It does seem like this might be explained by a leak somewhere?
I’ve been considering how hard it would be to build a system that can maintain a positive pressure difference in the house, so that it will reduce particulate inflow through cracks, other windows, etc. I’m not sure how hard that is to achieve.
I’m using one of these: https://blatn.com/products/brwissen-desktop-br-a18-air-quality-monitor-indoor-pollution-tester-for-co2-meter-pm1-0-pm2-5-pm10-particulate-matter-analyzer-hcho-formaldehyde-tvoc-air-gas-detector
I get the outdoor data from PurpleAir. There are two stations within a few blocks of me, and they both seem to report very similar numbers, though I have not done anything to formally estimate the error/variance.
Yes, and it does seem to depend somewhat on where the sensor is placed and what the circulation is. I took notes on where it was sitting, but I haven’t tried to notice any patterns yet. I had a fan running to circulate air in the room the whole time that data was being recorded. I did not open the door very many times.
Some, yes. I do expect the indoor PM2.5 to track it at least a little, since I would (naively, at least) expect the filtration system to work linearly (that is, it removes a percentage of particulates that is not dependent on the particulate concentration. But it does not seem to be linear, since it was removing a smaller fraction later in the day when the outdoor concentration was higher. It does seem like this might be explained by a leak somewhere?
I’ve been considering how hard it would be to build a system that can maintain a positive pressure difference in the house, so that it will reduce particulate inflow through cracks, other windows, etc. I’m not sure how hard that is to achieve.
Have you done experiments of your own?