Particle Sniffer For Pollution Point Sources

When measuring air quality, particulate matter is an important metric to watch. The PM2.5 rating refers to particulate matter that has a diameter of less than 2.5 micrometers. While it’s often measured by authorities on a city-wide basis, [rabbitcreek] wanted a way to track down point sources indoors.

The tool [rabbitcreek] built is in a similar form factor to a typical infrared workshop thermometer. Inside, it packs a Honeywell HPMA115S0-TIR laser particle sensor, hooked up to an ESP32 which runs the show. The sensor chosen makes things easy, with the device already set up with a blower and inlet and outlet ports for taking accurate readings.. Results are displayed on an SSD1306 OLED screen. It’s all wrapped up in a 3D printed case with a trigger grip, and a dog nose on the front which hints at the devices true purpose.

In testing, the device proves capable of detecting point sources of atmospheric particulates like flowers and a toaster. It’s something we’re sure would prove handy to those working in HVAC and environmental assessment industries. We’ve seen other rigs for monitoring particulates before, too. Video after the break.

13 thoughts on “Particle Sniffer For Pollution Point Sources

          1. Still does not make sense to me. If I have 1 lb of carrots in 10 lb of potatoes how many PPM is that?

            Particle size of air is what? The size of the molecule? Are we talking 500 grams of small particles in 1,000 kilograms of air? That’s a lot of air.

            Just trying to make sense of the numbers and I can’t.

          1. This is correct. The “PPM” shown on the display is a misspelling of “PM”. Not visible in the photo but to the right is “2.5”. So it is saying it is measuring in the PM2.5 range as opposed to the PM10 range.

            High end particle detection instruments have filters of various sizes and weigh them after a certain amount of air has passed – hence the standard micrograms per cubic meter measurement. The cheap detectors count particles and use an algorithm to estimate the µg/m3 measurement.

    1. Particulate sensors based on the light diffraction measure numerical concentration directly (number of particles in unit volume of air, usually per cubic meter). But the problem is that professional measurements are done by measuring mass of particles in unit volume of air (usually by filtering known amount of air on the filter with known mass). Therefore these low cost particulate sensors calculate mass concentration of particles based on numerical concentration, assuming that all particles are spherical and the specific density is constant and known (it’s not).

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