Why air quality monitors are the new back-to-school accessory


When Philadelphia architect Lizzie Rothwell sent her son to third grade this fall, she filled her blue LL Bean backpack with pencils, wide-lined paper and a portable carbon dioxide monitor.

The device enabled him to quickly assess the amount of fresh air circulating in the school. Low levels of CO2 would indicate he was well ventilated, reducing his son’s chances of catching the coronavirus.

But she quickly discovered that during lunch, CO2 levels in the cafeteria were almost double those recommended by the Centers for Disease Control and Prevention. She shared what she had learned with the principal and asked if the students could eat out instead.

“He expressed surprise that I had any data at all,” she said.

Ms Rothwell is one of a growing number of parents who are bringing CO2 monitors to schools in a clandestine effort to ensure their children’s classrooms are safe. Aranet, who makes a monitor popular with parents, says orders have doubled since the start of the new school year.

Some school systems have made monitors part of their official pandemic precautions. New York City distributed the devices to all public schools and the UK government To plans announced do the same.

But elsewhere, parents are taking matters into their own hands, sneaking in monitors – which can cost a hundred dollars or more – in their children’s backpacks or pants pockets.

Although the devices, which can be configured to take readings every few minutes, perform best when exposed to the open air, they can generate informative data as long as they are not completely sealed, the Dr. Alex Huffman, aerosol scientist at the University of Denver who sent the monitors to school with his children. (He recommended leaving the pockets of backpacks or pants open, or stowing the monitor in the mesh water bottle pocket that is now standard on many backpacks.)

Many of these parents have forged a community on Twitter, where they use the hashtag # CovidCO2 to exchange advice on how to smuggle monitors into the classroom, how to interpret the data they collect, and how to approach it. school with their discoveries.

Some school officials disapproved of these guerrilla aerial surveillance efforts, but parents say the devices armed them with data to defend their children.

“It is possible that the school district is not very happy with this because I think it gives us a window into the fact that maybe they are not taking ventilation as seriously as they should be,” Dr Huffman said.

The coronavirus is spread by tiny airborne droplets called aerosols. Improving indoor ventilation reduces the concentration of these aerosols and the risk of infection in an indoor space, but there is no easy way for members of the public to measure ventilation rate – let alone build up. viral aerosols – in shared spaces.

“Ideally there would be a machine that cost $ 100 and it would start beeping if the virus is in the air,” said Jose-Luis Jimenez, an aerosol scientist at the University of Colorado Boulder, who sends a monitor of carbon dioxide at school with her son. But in the absence of such a device, he said, “CO2 is something that provides an affordable and very significant shortcut.”

Every time we breathe out, we not only expel aerosols but also carbon dioxide; the worse the ventilation, the more carbon dioxide will build up in an occupied room.

“If we see CO2 increasing, it also implies that the aerosol concentration is increasing,” said Dr Huffman. “Even just bringing in a sensor for a day or two can give you a really interesting and useful window into the world of ventilation in that space. “

Jeanne Norris, who lives in the St. Louis area, said she bought her instructor after losing faith in officials at her son’s school district.

“They just weren’t very transparent about their breakdown,” she said. “They say it’s okay and they did their own tests, but then they wouldn’t share this data with me.”

Ms Norris and her husband are both science teachers, and so far their data suggests ventilation is excellent in both of their classrooms. But CO2 levels in her son’s classroom sometimes exceed 1,300 parts per million. The CDC recommends that indoor carbon dioxide levels stay below 800 ppm

After collecting more data, she plans to relay her findings to school officials and ask them to improve ventilation. “I am ready to be creative and to think with them,” she said.

Some parents have had results. When Jeremy Chrysler, of Conway, Ark., Sent in a monitor with his 13-year-old daughter this fall, CO2 readings peaked at 4,000 ppm.

He shared his findings with district officials, who discovered that two components of the school’s HVAC system were not functioning properly. Once the units were repaired, the CO2 levels dropped.

“What my measurements have shown is that measuring CO2 can identify problems and sometimes those problems are easy to solve,” he said.

Although Ms Rothwell did not convince her son’s school to move lunch outside, the principal said he was committed to improving the ventilation in the cafeteria, she said.

“There are success stories,” said Kimberly Prather, atmospheric chemist at the University of California, San Diego. “Unfortunately, I have heard more from parents rejected.”

After Shanon Kerr, from Waterloo, Canada, found high levels of CO2 in some of her daughter’s school spaces, she asked district officials to monitor indoor air quality throughout the building, even offering her own CO2 monitor. “They were very contemptuous,” she said.

In an email to The Times, Loretta Notten, director of education for the Waterloo Catholic District School Board, said follow-up tests in classrooms identified by Ms Kerr revealed that carbon dioxide levels “are rising. were within acceptable parameters ”.

Air quality tests are carried out as needed, she said: “The Council does not intend to carry out continuous monitoring of carbon dioxide.”

(Ms. Kerr has also encountered resistance closer to home. Her daughter no longer wants to take the instructor to school. “I bribed her with KitKat chocolate bars but it doesn’t work anymore,” he said. she said.)

Graham Freeman, a father of two boys in Santa Cruz, Calif., Said his request to send CO2 monitors to school with his sons was denied.

Kris Munro, the superintendent of schools in the city of Santa Cruz, said she was confident in the ventilation improvements made by the district last winter and that it would be inappropriate to put individual students in a position to watch. air quality in schools.

“It’s our responsibility to make sure every space is safe,” she said. “Not just for people to come to campus to find out: is a specific space safe? “

Mr. Freeman still sent the monitors to school, stowed away in the pockets of his sons’ cargo pants. He was pleasantly surprised by the readings, which remained below 700 ppm as long as the classroom doors and windows were open.

But monitors caught a small spike, when the CO2 surpassed 900 ppm, during a lockdown exercise at her son’s middle school, when the teacher closed the classroom door.

Thus, his sons will continue to bring the devices to school for the indefinite future. “We’re going to be carrying a lot of REI cargo pants and CO2 monitors in the pockets,” he said.

There are limits to surveillance. Some devices are more reliable than others, and readings can be affected by a variety of factors, including the location of the monitor.

Children can still catch the virus in spaces with low CO2 levels and good ventilation. And high-quality air filters can trap viral aerosols, but have no effect on carbon dioxide levels. So, in schools that have installed these filters, CO2 readings alone can overestimate the risk of viral transmission.

But even in the absence of the virus, reducing indoor carbon dioxide levels can have benefits. Studies show that even moderately high levels of gas can cloud reflection and that improved ventilation can increase performance on cognitive tasks.

Of course, many families can’t afford a $ 100 air quality monitor – and they shouldn’t have to, parents and scientists said.

Mr Chrysler, whose CO2 readings prompted his Arkansas district to repair its HVAC system, is now lobbying authorities to purchase air quality monitors for every classroom in the district.

Referring to Belgium, which has mandated CO2 monitors in restaurants, gyms and other buildings, Dr Jimenez said he would like all indoor public spaces to provide permanent real-time displays of carbon dioxide levels. carbon: “This is something we should be doing all the time. in schools but also in all the places where we share the air.


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