Cheaper Air Quality Sensors: It’s Now Easier to Track the Smoke and Air Pollution

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As we face the climate catastrophe, a new air quality sensor will make it easier to track the smoke and air pollution of wildfires.

The West Coast of the United States is covered in smoke. Real-time updates are posted on social media that clearly show just have bad the air quality is.

PurpleAir has been releasing the majority of the information from their relatively inexpensive sensors. These sensors have only been available in recent years, but they’re revolutionising the way government data is being tracked.

It has only been the past decade where non-scientists had access to air-quality sensors that measure particle pollution of things such as smoke, dust, and soot at a low cost. Fire seasons in America are becoming increasingly more dangerous, making PurpleAir, and others like them, more popular.

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ALTERNATIVE AIR QUALITY SENSORS ARE NOT ONLY BECOMING BETTER, THEY ARE BECOMING CHEAPER.

Nuria Castell, a senior scientist as the Norwegian Institute for Air Research (NILU), states, “the power is not in one individual monitoring their house, but in the individual contributing his data, and another individual, and the municipality, and a scientist.” Castell, who studies new pollution monitoring, continues, “We put all this data together and then we have something.”

By creating these maps of air quality, urban planning and air can become cleaner and better in relation to fire, industry and other pollutions.

Dust problems were actually the instigator of PurpleAir. Adrian Dybwad, owner and CEO of PurpleAir, used to just watch the dust settle on his home from the gravel mine in Salt Lake City, Utah. Dybwad became interested in the ways this dust was affecting air quality, but he could not find a sensor that could do what he wanted and not cost a small fortune.

Dybwad then set out o create his own sensor in 2015, with a background in programming, networking and surface-mount electronics. Now, purpleAir has a network of more than 9,7000 air quality sensors that are low-cost. These sensors produce data in near-real-time. PurpleAir sensor data was also featured in the US Environment Protection Agency and US Forest Service data into its AirNow fire and smoke map.

While many may not think that $280 for these sensors are not cheap, but some heavy-duty equipment typically used by research van cost up to $50,000.

This huge price range is an indicator of how each air quality sensor is produced and operated differently. The high-quality sensors that can cost thousands of dollars can use a lot of energy but are carefully calibrated. Some of the sensors even require permits for their use and operation due to their use of beta rays emitted a radioactive source.

Cheaper air quality sensors collect their information through tiny glass fibres with filters that vibrate, which alters depending on the particles collected. Lastly, there is the old-fashioned sensor that is much slower and collects data by capturing particles on a filter and weighing them in a lab.

In comparison, PurpleAir uses laser particle counters to measure particles. This method, “light scattering” Dybwad explains, “basically shine[s] a laser through the air and then the particles in the air reflect the light and the detector picks up on those reflections.”

It’s better than nothing.

While the sensors used by professional researchers are significantly more accurate, they are way too expensive for just anyone to deploy. Anthony Wexler, director of the Air Quality Research Centre at the University of California, says “you have a trade-off between high accuracy in a limited number of locations and low accuracy in many locations.” He states that it is better to have many low-cost sensors than very few high-cost sensors.

Further, he explains that these low-cost sensors allow communities to assess their air quality and have evidence to support their claims of pollution to regulators.

Whether by advances to algorithms or the equipment itself, Castell is confident that PurpleAir and other low-cost sensors can become more accurate with time. Currently, the sensors can miss very small particles or even get confused by water droplets and humidity. However, they have proven to raise awareness to take action against air pollution. Even if the sensors can’t be as accurate as high-quality sensors, they are accurate enough to inform people currently across the West Coast whether they should find shelter.

Castell states, “The [low-cost] sensor technologies can really play a big, big role if we take care of the limitations. I’m very positive that technologically we will advance.”