Back to the Office in the Post-Mask Era

What can sewage and carbon dioxide tell you?

After two years of all COVID, all the time, the pandemic has dropped out of the news. The expectation when something drops out of the news is that it’s not a problem anymore — we can all forget about it and go on with our normal lives. Wonderful. Except according to the WHO we are still in the middle of the pandemic.

Depending on whether you were on Team Mask or Team Overblown, you might or might not be thrilled to get back to a Normal that you’re not quite sure exists yet — or will ever exist.

Most people who have been working from home (79% in fact) prefer to stay that way, regardless of politics, and going back to the office has been wildly unpopular. When President Biden said, “It’s time for America to get back to work and fill our great downtowns again with people. People working from home can feel safe and begin to return to their offices,” I think he missed the point. Office workers don’t want to stay at home because they feel scared or unsafe. They want to stay home because their life is better that way. Many workplaces seem to be struggling with the problem of bringing reluctant workers back onsite.

But even if they’re not “afraid” of returning to the office, many of my friends who have been asked to return to onsite work this spring are not happy, for a wide range of reasons. They have expressed concerns about commuting in crowded conditions, putting their young kids in day care, going back into a crowded office environment — because even if the risks are small, the risks are for what? To do work on computers that they could just as easily (and much more conveniently) do at home.

Most people I know are more than willing to take small risks for things that are important to them: to get together with family, to have parties to mark special events or celebrations. They’re not hiding under the bed, quaking in fear from the virus. Just the same, though, taking on even a small risk by congregating in a stuffy conference room that could have been a Zoom call doesn’t make sense.

I can’t disagree. If you’re a doctor, nurse, or other essential worker, you sign up for a certain amount of risk as part of your job. But if you’re an office worker who’s successfully worked from home for two years now, it’s harder to be told you need to come back.

Other people have more serious concerns about going back to a crowded office, which are as individual as the people themselves: some care for elderly parents; some have kids who are too young to be vaccinated; some have a health condition that puts them at high risk for a bad outcome.

Even if you’re not in a high-risk category today, if you live long enough, someday you will be. And many people’s concern is not that COVID will kill them, but rather that they might be among the unlucky few to have long COVID or other bad outcomes. So it makes sense that many people continue to assess risks and do what they can to live life while also making sensible choices.

Wastewater, Not Cases

Several people have asked me whether the local rates of COVID are really as low as they look on our local dashboard, especially if “everyone is testing at home now” — one friend asked if it’s realistic to think someone who has a positive home test is going to report it to the County. Probably not. People wonder if that makes case rates look lower than they are. Probably.

That’s why many epidemiologists, such as Katelyn Jetelina, are recommending looking at wastewater surveillance, which looks at virus particles in local wastewater — it’s like a meta-COVID-test for the entire community.

Here for example, is a graph showing wastewater surveillance in one county, and it captures the omicron surge this winter:

If you were to look at the local case rates for this county, again, you would only see reported cases — but you wouldn’t know if they’re really low, or if it’s just that very few people are bothering to report. But by looking at the wastewater, you can see that the amount of virus in the local wastewater is low and steady.

So that’s what I’m monitoring these days, when I’m making choices about what to do and how careful to be. The CDC has some resources to try to find local wastewater numbers in your area, or you can google your local health department.

CO2 Monitoring

But in some cases, people aren’t given the choice about how careful to be — they’re just being asked to return to their office jobs. What can you do to mitigate your exposure in the office? One thing you can do is to buy an inexpensive carbon dioxide (CO2) monitor. I found one online for about $60.

Why CO2? The levels of exhaled CO2 in an environment serve as a proxy for levels of “other exhaled stuff” — such as exhaled aerosols — in an environment. The exhaled aerosols of course might or might not contain the SARS-2 virus, but a room with a lot of exhaled CO2 has potentially more exhaled aerosolized virus in it (if someone is infected) compared with a room with levels more typical of outside air.

Remember that unless conditions are very crowded, it’s very difficult to become infected with SARS-2 while you’re outdoors — so air that’s as dilute as outdoor air is a good thing to aim for.

Question #9 on this CDC page gives the CDC’s opinion on whether CO2 monitoring can be useful in promoting good ventilation in a room. (TL;DR: Yes.)

Far from being “one more thing to worry about,” I find it very easy and reassuring to be able to take simple measures to improve indoor air quality, both at work and home.

This article by Di Gilio et al. in Environmental Research is one of many articles that discuss indoor air monitoring (although there are many other such articles) and the effect it can have when non-experts keep an eye on CO2 levels and take simple measures to control it. This figure from the article shows the risk classification scheme and the suggested actions.

For example, if the CO2 levels in a room rise above 700 ppm, the first thing to try is to open the door. If the levels are still high, you move to the next action, which is to open the windows for 10 minutes. And so on.

This figure shows the effect in one Italian school of taking those simple actions:

In the baseline condition (the dark red line), where the teachers were told not to pay attention to levels or take any actions, CO2 levels (and therefore other exhaled aerosols) were often above levels considered “high risk.”

In the test condition (the blue line), where teachers were keeping an eye on CO2 levels and adjusting accordingly—opening a window, say—CO2 levels were easily controlled. It seems like a very easy way to mitigate risk.

I bought a simple CO2 monitor for some of the office spaces at work and discovered it is really that easy. Opening a door or window quickly brings CO2 levels down — often at or near the levels of outdoor air (which is about 450 ppm). I’ve tested it at home, too, just for comparison. Opening a window changes levels very quickly.

So if you’re stuck in an office environment and you’re concerned about your exposure to stuffy indoor air, this might be one thing to try.

HEPA Filtering

Finally, you might want to bring a HEPA filter to the office. While HEPA filtering doesn’t remove particles the size of the virus, it does typically remove many particles the size of the things the virus hitches a ride to. According to aerosol scientist Faye MacNeil at Columbia, “yes, HEPA filters can catch particles that contain coronaviruses. People expel droplets of respiratory fluid, saliva, and possibly viruses into the air when breathing, coughing, and talking. Even if the water in the droplet evaporates, the droplets contain salts, proteins, and other material in addition to any virus, which means the remaining particles are typically a few microns in size, making them fairly easy to trap with a HEPA filter.”

Similarly, some research done by a team at Mayo Clinic found that “96% plus or minus 2% of aerosols of all sizes generated during heavy exercise were removed from the air by the HEPA filter.”

HEPA filters are fairly easy to find online. The most important considerations are to get one that’s big enough for the square footage you want to cover, and to run it whenever the room is occupied (and ideally an hour or two before and after as well—some HEPA filters have timers you can set up).

Or, You Can Look for a More Flexible Job

But if none of that makes going back to the office worthwhile, you can be among the office workers surveyed by Future Forum Pulse (April 19, 2022) who say they are “definitely” going to look for a more flexible job: “Workers who say that they are unsatisfied with their current level of flexibility—both in where and when they work—are now three times as likely to say they will ‘definitely’ look for a new job in the coming year, compared to those who report satisfaction with their work flexibility.”