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Air Quality: Easy to Measure, Tough to Fix

Wildfire season shows the limits of air purifiers

3 min read
Illustration of a phone with with a sensor on top.
Harry Campbell

The summer of 2020 brought wildfire to Portland, Ore., as it did to so many other cities across the world. All outdoor activity in my neighborhood ceased for weeks, yet staying indoors didn't guarantee relief. The worst days left me woozy as my lone air purifier, whirring like a jet engine, failed to keep up.

Obviously, the air in my home was bad. But I had no idea of how bad because, like most people, I had no way to measure it.

That's changing, thanks to indoor air-quality monitors like Airthings' View Plus. Sold for US $299, the View Plus can gauge seven critical metrics: radon, particulates, carbon dioxide, humidity, temperature, volatile organic compounds, and air pressure.

The monitor proved useful. I learned that cooking dinner can spike particulates into unhealthy territory for several hours, a sign that my oven vent is not working properly. The monitor also reported low levels of radon, proof that my home's radon mitigation system is doing its job.

I had the monitor installed, working, and connected to the Airthings app less than 10 minutes after it arrived at my doorstep, in June. Reading the app was easy: It color-coded the results as good, fair, or poor. I have only one monitor, but the system can support multiple devices, making it possible to sniff out how air quality differs between rooms. You can also just move the device, though it needs time to update its readings.

Airthings' monitor is unusual because it combines a radon sensor with other air-quality metrics, but it's certainly not alone. Alternatives are available from IQAir, Kaiterra,and Temtop, among others, and they range in price from $80 to $300. These monitors don't require permanent installation, so they're suitable for renters as well as owners.

Of course, it's not enough to detect air pollutants; you must also remove them. That problem is more difficult.

Ionization can itself create ozone. The state of California has banned such ozone generators entirely.

Air purifiers surged in popularity through the second half of 2020 in response to dual airborne threats of COVID-19 and wildfire smoke. Companies responded to this demand at 2021's all-digital Consumer Electronics Show. LG led its presentation with personal air purifiers instead of televisions. Coway, Luft, and Scosche all showed new models, with Coway winning a CES Innovation Award for its new Design Flex purifiers.

Unfortunately, consumers newly educated on indoor air quality will be puzzled about which air purifier, if any, is appropriate. Purifiers vary widely in the pollutants they claim to clean and how they claim to clean them. Most models advertise a HEPA air filter, which promises a specific standard of efficiency based on its rating, but this is often combined with unproven UV light, ionization, and ozone technologies that vaguely claim to catch toxins and kill pathogens, even COVID-19. This is the wild, wild west of air purification.

It's true that an activated carbon filter can remove volatile organic compounds and ozone from the air. There's no common standard for efficiency, however, so shoppers must cross their fingers and hope for the best. Ionization, another popular feature, is no better. Studies suggest ionization can destroy viruses and bacteria in the air but, again, there's no common standard.

In fact, ionization can itself create ozone. The state of California has banned such ozone generators entirely, but you'll still find these products on Amazon and other retailers. Studies even suggest the ionization feature in some purifiers may interact with the air in unpredictable ways, adding new pollutants.

It's vital that companies designing air purifiers police their products and work together on standards that make sense to consumers. 2021's harsh fire season will keep demand high, but new, easy-to-use monitors like the Airthings View Plus will leave homeowners better informed about air quality—and ready to kick unproven purifiers to the curb.

This article appears in the October 2021 print issue as "The Indoor Air-Quality Paradox."

The Conversation (2)
Thomas Valone19 Nov, 2021

This article fails to clarify the fresh air concentration of ozone (about 30 ppb) which has numerous benefits that have escaped the State of California lawmakers. Every outdoor wilderness environment has at least 30 ppb of clean ozone, which gives it a fresh smell, while keeping germs in check, including in the respiratory system. I actually have measured 40 ppb outdoors in Colorado Springs CO where Nikola Tesla did his atmospheric research. Reproducing this limited amount of ozone indoors, where there normally is NONE, should not be a crime but instead an opportunity for virucidal and bacteriostatic sanitation on an individual level. Air systems with UV lights also produce ozone for the same purpose and usually have a filter for limiting ozone concentration. However, personal ozone generating purifiers available online never produce a room concentration above 30 ppb and should be made available for California air purification indoors. Let citizens make their own decision about a one-time investment in fresh indoor air. Dirty ozone present in smog is nature's way of trying to oxidize the SOx and NOx present in urban exhaust. Clean ozone on the level of outdoor concentration is never harmful but instead a natural gift from lightning, pine forests, and water falls. I have also published an explanatory article two decades ago on this topic:

J Wagner03 Nov, 2021

As I read the article I wonder why someone is not investigating the NASA based equipment manufactured by AERUS. It does not produce ozone and sanitizes the room air in 3 minutes and room surfaces in 3 hours. This equipment should be examined for application to kill all virus in the public and private.

Deep Learning Could Bring the Concert Experience Home

The century-old quest for truly realistic sound production is finally paying off

12 min read
Image containing multiple aspects such as instruments and left and right open hands.
Stuart Bradford

Now that recorded sound has become ubiquitous, we hardly think about it. From our smartphones, smart speakers, TVs, radios, disc players, and car sound systems, it’s an enduring and enjoyable presence in our lives. In 2017, a survey by the polling firm Nielsen suggested that some 90 percent of the U.S. population listens to music regularly and that, on average, they do so 32 hours per week.

Behind this free-flowing pleasure are enormous industries applying technology to the long-standing goal of reproducing sound with the greatest possible realism. From Edison’s phonograph and the horn speakers of the 1880s, successive generations of engineers in pursuit of this ideal invented and exploited countless technologies: triode vacuum tubes, dynamic loudspeakers, magnetic phonograph cartridges, solid-state amplifier circuits in scores of different topologies, electrostatic speakers, optical discs, stereo, and surround sound. And over the past five decades, digital technologies, like audio compression and streaming, have transformed the music industry.

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