How to think like an aerosol scientist this holiday season to stay sane

Since the pandemic began, public health officials have been warning people about the high risk associated with visiting restaurants and bars. At the beginning of the pandemic, these venues were closed. But now they’re back, with zero restrictions and limited alfresco dining due to colder weather and the waning of relaxed pandemic-era regulations.

When Jimenez walked into a crowded Pearl Street restaurant the weekend before Halloween, he immediately noticed a lack of open windows or doors to let air circulate.

“The counter reads 1,060, which is definitely not good for a place where people are eating and talking without masks,” Jimenez said.

On a recent visit to the college town of Madison, Wisconsin, Daley documented the highest level he has seen to date. There were more than 3,500. This was in a piano bar, an older building where ventilation was poor and windows and doors didn’t open. As it filled with college-aged students and mostly 20-year-olds, there was hardly a N95 mask on display.

The number rose as more people entered the bar.

Don’t judge a book by its cover, but Jimenez cautioned. Even if a restaurant or bar looks crowded, other factors can play a role.

“It’s hard to know what they’re doing with the ventilation systems. Sometimes it’s always the same,” Jimenez said at a basement bar in Boulder. “Some ventilation systems run more when there are more people, so it’s hard to predict. So measuring is a good thing, you know?”

Air quality is part of a “vaccine-plus” approach to ending the global pandemic, say hundreds of scientists

Experts from more than 100 countries identified indoor air quality as crucial to ending the COVID-19 pandemic as a public health threat in a study published in the journal Nature. Jimenez was one of the co-authors.

The paper said, “Current evidence led panelists to a nearly unanimous consensus that SARS-CoV-2 is an airborne virus that poses the highest risk of transmission indoors with poor ventilation.” It said governments should take preventative measures such as ventilation and regulate and promote air filtration, and high priority should be given to preventing transmission in the workplace, educational establishments and commercial centers.

She called the virus a “persistent and dangerous global health threat” and urged a “vaccine-plus” approach that also includes increased masking, testing and treatment. The study included 57 recommendations from 386 multidisciplinary experts from more than 100 countries and territories. The experts conducted a so-called Delphi study, which challenges experts to find a consensus on answers to complex research questions.

“Unfortunately, COVID-19 is not over yet,” Jimenez said in a CU press release. “But there are many things we can and should do about it here in the US and around the world, and a high priority should be paying attention to that and taking action by cleaning our indoor air.”

20221018-COVID-AEROSOL-DIAHart Van Denburg/CPR News
Jose-Luis Jimenez is a professor at CU Boulder whose expertise includes aerosols, atmospheric chemistry and disease transmission. At Denver International Airport on Monday, October 18, 2022.

A push for better indoor air quality at DIA

The crisis has sparked new efforts and reforms aimed at improving indoor air quality, including Japan, Taiwan, South Korea and Belgium, Jimenez said.

Legislators in Belgium have passed a ventilation plan that obliges publicly accessible places such as bars, restaurants, cinemas, theaters and gyms to monitor air quality and have a visible CO2 monitor. This sensor must not be in the immediate vicinity of a door or window, which would reduce readings but not reflect true levels in a room, according to the Brussels Times.

Attempting to educate the public about indoor air quality has become a global movement. Jimenez dreams of having a CO2 monitor on every building, plane, train for people to see for themselves.

Denver International Airport is currently monitoring carbon levels in all areas of the airport office building, main terminal and concourses, Public Information Officer Stephanie Figueroa said.

And there is more to come on this front. Hall B and new additions to Halls A and C have a monitoring system “that automatically triggers fresh air” to be introduced into the HVAC system once CO2 levels exceed 900-1,000ppm, she wrote in an email. The main terminal building and Concourses A and C will have an automatic system to introduce fresh air as part of upgrades related to a new environmental performance contract that started construction a few weeks ago.

DIA is also installing new CO2 sensors around the airport as part of renovations and will post readings on thermostats for the public to see, she said.

For its part, RTD said it agrees that CO2 monitoring gives an indication of a space’s ability to ventilate and that it is an indicator of air quality.

Senior PR specialist Laurie Huff said the agency’s trains are well ventilated and the readings on a CO2 monitor “do not directly correspond to the risk of infection” – they correspond to the number of people breathing in the room. Several other factors must be considered “to understand what happens to the air on a bus, plane, or train, including but not limited to circulation or movement within the vehicle, filtration, temperature, and humidity,” Huff wrote in an E- Mail.

20221018-COVID-AEROSOL-DIAHart Van Denburg/CPR News
Jose-Luis Jimenez uses a carbon dioxide meter as a proxy to measure the possible presence of COVID-19 in the air on an RTD-A Line train bound for Denver International Airport on Monday, October 18, 2022.

On its website, RTD looks at air quality in light rail, commuter trains and buses, as well as in the underground bus concourse at Union Station.

On commuter rail routes like the A line, according to DIA, the website says the HVAC system changes the air in each car “roughly every four minutes — or 15 times an hour — with the doors closed, an estimate set by a vehicle engineer.” was .” Every time an S-Bahn train stops at a station and the doors open, additional fresh air is introduced into the passenger compartment.

Each car has two rooftop HVAC units that run independently in case one fails. With both roof units running, each car is fed 3,800 cubic feet of air per minute, of which 29 percent is fresh and 71 percent is recirculated, the site said. This air is supplied via overhead ducts and registers that run the length of the vehicle and is returned to each unit in the ceiling near the passenger doors at each end.

bottom line?

“The more people there are in close proximity, the higher the risk,” Huff said. “RTD can somewhat mitigate this risk through ventilation and filtration, but we will not eliminate it. How much risk each person is willing to take is a personal choice.”

Paolo Zialcita/CPR News
CPR reporter Paolo Zialcita carried out many of the air quality measurements.

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