Using a new generation of laser particle counters to provide real time measurement of (amongst other data), PM1.0, PM2.5 and PM10. PurpleAir sensors are easy to install, requiring a power outlet and WiFi. They use WiFi to report in real time to the PurpleAir Map.
They seem to range from $179-$259 and detect:
PurpleAir sensors use a fan to draw air past a laser, causing reflections from any particles in the air. These reflections are used to count particles in six sizes between 0.3μm and 10μm diameter.
Using one second particle counts, estimated total mass for PM1.0, PM2.5 and PM10 is averaged by the PurpleAir Internet of Things (IOT) control board.
Hi Jeff - My guess is that if Weather Underground and EPA and CARB have been involved the product is probably pretty good. And Weather Underground is a great idea for a host network. They presented their initial ideas for this at an EPA community sensor conference in RTP NC several years ago. Dylos also makes some pretty well-regarded instruments that measure pretty small airborne particles. Ultimately it would be most helpful to have relatively inexpensive ultrafine particle (UFP) sensors that could count particles per cubic centimeter in the 5 nm to 100 nm size range.
Our bench instruments, used in the Boston area by Tufts and community partners like Somerville Transportation Equity Partnership (STEP) both in stationary boxes and in mobile labs, generally count between 10,000 and 50,000 UFP per cubic centimeter but sometimes more, depending on meteorology and proximity to sources, especially mobile sources like highways, rail and aviation. Or some indoor sources like candles and cooking. These monitors are both accurate and pretty expensive. There are some very inexpensive particle sensors, such as Shinyeis, but reports are that they are not always accurate.
As you know, I would also love to see a bicycle sensor network that could calibrate off of stationary monitors from time to time. Could be done with bike share. But so far cost is a real barrier for measuring ultrafine particles. Maybe the new nano labs will come up with something soon. - Cheers, Wig
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I tried to put a long answer here but it kept throwing errors so I wrote a note with my thoughts on this issue:
@GreenFrogg I was checking out your list of sensors on this page and didn't see the Purple Air. Have you worked with it? what are your thoughts on it in comparison to the ones you've been working with?
I don't have experience with the Purple Air. The page is an overview made by the Dutch institute of environmental health (RIVM). They coordinate. You can contact them directly about their knowledge about the Purple Air.
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Hi @BrandonFeenstra !
I had a group asking me about the Dylos this morning, so I went to the AQMD website and found the report for it like the one you shared here (http://yourstory.aqmd.gov/aq-spec/evaluations/field <-- really useful link for anyone thinking about low cost PM monitoring!), but I was wondering if there's a report that does an overview of what was found on all of these?