"Data Soup" Blog

Peter Klam

So last week I ordered and received a carbon dioxide meter. It allows me to measure the CO2 concentration in parts per million for any space. On Friday, I went about a not particularly scientific but quite interesting analysis of our indoor spaces in the AMP Building.  

The idea behind this is that humans exhale CO2, so measuring the concentration in a given room gives a bit of a window into how much ventilation is helping to keep rooms relatively clear and clean. This is not a scientific examination by any means, and scientists in the field of indoor air quality warn against taking the results from these tests too seriously. For one thing, CO2 is naturally occurring in the air. In fact, my reading from outside in the fresh air was 385 ppm, which is less than double my highest indoor reading. Measuring CO2 is also not equivalent to measuring how clean the air gets of particulate matter. Aerosolized exhaled particles won’t register on a CO2 meter, and those particles can stick around even when exhaled CO2 is diminished in a room via mitigation (open windows and such). So some of the figuring that we have to do in this case is by logical deduction (not necessarily terribly scientific, but useful nonetheless). If the air is being cleared of a portion of the CO2 that folks are exhaling, it is almost certainly being cleared of other aerosolized particulate matter that is also being exhaled. This doesn’t make the rooms ‘safe’ in any absolute sense, but it does contribute to a safer environment.  

It is also worth noting that studies suggest that the severity of COVID-19 is related to the concentration of the virus in the inhaled dose. So in the worst-case scenario that we have someone in a classroom who is sick with COVID-19 but who is still unaware of this, increasing circulation can help to decrease the severity if anyone else in the classroom were to contract the disease from that person. Bear in mind that our other mitigations—mask-wearing, social distancing, and cleaning protocols—would have a pretty good chance of keeping folks safe even if an infected person were in the room. That’s what those mitigations are for—to prevent the spread of the disease if it does come into our environment. Air exchange is just another way for us to make transmission as unlikely as possible and to minimize the severity if the disease were transmitted.  

I measured the CO2 concentration of different classrooms under different conditions, and I also took a baseline measure outside. The findings were quite revealing. Even a classroom that had been empty all day registered rather more CO2 than outside. Outside varied between 350 and 490. At climate.gov, they report that the average outside CO2 concentration is 409 ppm, so we come in a bit lower than that, at least at this time of year. At any rate, moving inside, the ppm was definitely higher. I measured 483 ppm in an empty classroom and 523 ppm in the gathering space. Bear in mind that only the 7th grade was on campus on Friday, and they were all in the AMP Building. In a classroom with kids talking (masked and socially-distanced, mind you) and the outside windows closed, the meter gave a reading of just over 600 ppm, while in a classroom of kids reading quietly, it registered a touch lower—at 584 ppm. What was interesting then, now that something of an indoor baseline had been established, was to engage in mitigation by opening windows. With the class continuing to read silently, I opened 5 windows and propped the back door open. Within 5 minutes, the CO2 ppm had dropped by over 100. And when I measured after the kids had gone home and the building was empty, the room was back to the equivalent of the outside air—380 ppm—after 5 minutes with the windows and door still open.  

What is evident from this is that the effect of open windows and doors is dramatic. The CO2 ppm goes down quickly with the windows open, and it stands to reason that particulate matter is similarly dispersed, and potentially expelled—at least for some of it, as a result. Today was pretty cold, and we had doors opened and closed at different times to try to balance warmth in the classroom with fresh air from outside. But as we move towards and into spring, we will be leaving windows and doors open more and more as a way of keeping our environments, and our kids and teachers, as safe as possible during the pandemic.  

As far as the metrics go, we had a clean slate this week—zero cases of COVID out of 172 people who were tested. The community metrics continue to be quite low. The 7-day average of positive tests per 100K remains below 12—as a reminder, 15 is considered elevated by Montgomery County, so we’re comfortably below that number. The positivity rate also continues to be quite low—below 3% as a 7-day average. The percentage growth has ticked into the region of positive growth over the past three days, which is something to keep an eye on. But COVID has been shrinking in the area for over a month—which is why we’ve reached such low levels—so to have it grow back a little bit still needs to be put into an overall context of a substantial easing in terms of the virus’s presence in our community since mid-January.  

Peter Klam

So it has now happened. For the first time since we returned from Winter Break, we had had a positive test result from our weekly testing, and we now have a group of students and a teacher quarantining. Given our conversations with the family in the past day, it would not be surprising to find out that this was a false positive. But whether it is a false positive or not, it gives us the opportunity to discuss some of what this means for us.

First, it feels important to say that this isn’t surprising or unexpected. COVID-19 is in the greater community, and it seems like the most reasonable conclusion is that every so often, a case would appear on campus. Whether this is the first case or not, I expect that it will not be our last. Our community agreement is strong, and like this family, we expect that all of our families are abiding by the guidelines in that agreement. But also like this family, who abided by those guidelines, there is the risk of transmission because this disease is out there in the community—guidelines or not. It is important that we all recognize that the risks of transmission are not eliminated at this point, even though our community has been case-free until now and the metrics in the surrounding community are fairly low and dropping. It’s out there. And it’s going to get onto campus at some point.

The mitigation measures that we take are done exactly for cases like this. Mitigation presupposes that COVID will make it onto campus. We engage in mitigation so that when it does, there will be no transmission on campus. Our mitigation strategies are not designed to keep COVID off campus. They are designed to keep our community members safe in the inevitable (and hopefully rare) instances when it makes it onto campus. The rate of transmission on school ground nationwide has been very low precisely because schools have been so much better at mitigation than many other businesses and organizations. And we are implementing ALL of the CDC recommended strategies, including frequent cleaning and handwashing, social distancing, cohorting, and other mitigations. I am more than hopeful—I am optimistic—that we will find that there were no cases of on-campus transmission from this isolated case. There are no guarantees, of course. But I am optimistic nonetheless. And if we do find that there weren’t any, that will say a lot about our mitigation (and the CDC-recommended mitigation strategies in general) and how effective they are.

When a case of COVID comes onto campus, Courtney—our resident expert—is in close communication with the county Health Department so that we are engaging in all of their required countermeasures to ensure that our community remains safe. We are very careful to follow their guidance and eager to make sure that isolated cases remain isolated. The safety of the community is of paramount importance.

Most teachers have now received their first dose of the vaccine, and new analysis of the vaccine trials suggests that the first dose of both local vaccines, Pfizer and Moderna, give over 92% protection from contracting a symptomatic case of COVID-19. And while that doesn’t help the students in the classroom yet, Middle School teachers cross between cohorts and cross each other’s paths more frequently than kids. So their protection does reduce the risk of transmission beyond the boundaries of the cohort.

The most important takeaways, to me at least, are that this isn’t unexpected, that our mitigations are designed to deal with cases exactly like this one, and that we are carefully following all of the expert requirements and guidance to maintain a safe community when something like this happens. I often talk about risk tolerance as being a key factor in decision-making both organizationally and for families. The likelihood that isolated cases of COVID-19 make it one campus must be part of our calculations—individually or collectively—when we assess our tolerance for risk in being on campus or sending our kids there.

Peter Klam

Life at Green Acres has been going smoothly, with the exception of the weather. This year brought new meaning to “dry January,” as we had few days of precipitation and little worry about snow, sleet, or ice.  February seems to be making up for the shortfall. For Rebecca and me, this has made for a challenging situation, as we are forced to make weather decisions that we previously relied on Montgomery County to make when they were not teaching and learning remotely. We are doing our best to make the safest decisions for our community, understanding that being at school is important but being safe is more important, and acknowledging that learning from home is not ideal but is sometimes necessary. In the mornings, we are in communication with staff members from different parts of the county to understand what the conditions are, and we are using our best judgment to determine what is safe.

Almost no news seems like great news on the pandemic front. We have had no new COVID cases at school since we began weekly testing, which is very heartening. We earnestly hope that this trend continues. The broader community statistics also continue to drop; we’ve already crossed the threshold of a 5% positivity rate in Montgomery County, and we are at 18.7 cases per 100k as of Tuesday—a dramatic improvement considering that almost exactly a month ago (January 12, to be exact) we hit nearly 50 cases per 100k. These put the statistical measures below or close to the MCPS thresholds—which says an awful lot considering how stringent they have been with the metrics compared to other counties and municipalities. 


The more interesting local pandemic news comes in the area of vaccination. If you’re following, you are probably aware of some of this. It seems that Montgomery County and the State of Maryland are not getting along very well. The State of Maryland claims that Montgomery County must be sitting on vaccine doses since they’ve given out so few, but Montgomery County insists that they’ve given out almost all of the vaccine doses they have, holding a few back to be distributed across the week so as not to create a logjam on a particular day at a particular vaccination site.

Well, the state has reacted by reducing the number of doses they’re distributing to Montgomery County, and you can imagine how well that’s gone over with the county folks! Either in reaction to this or by total coincidence, the county has removed their vaccine count from their website, so you can no longer see the numbers that the county reports—or, perhaps more to the point, the county has ceased to report numbers. This makes sense because it was probably a source of tension in the state-county relationship. The county reported distributing very few doses over their final week of reporting—easily fewer than 200 doses per day. The state, on the other hand, was reporting 2000-3000 doses distributed to Montgomery County residents per day. Part of that discrepancy is undoubtedly due to the fact that the state has been active in immunizing eligible people, so their count would be higher assuming that Montgomery County’s count only included residents they, themselves, vaccinated. But I also think that the discrepancy looked bad enough that the state accused the county of sitting on vaccine and as a result, they reduced the county’s weekly allotment of state supplies. So Montgomery County took their data offline and left it at that. If they want vaccine doses to distribute, the State has all the cards.


So the county vaccine totals reported by the state keep on going up, which is somewhat encouraging. But relative to population, it goes up pretty slowly. They have distributed nearly 10,000 doses to Montgomery County Residents so far this week. It sounds like a lot, but it is just short of 1% of county residents. The landscape is confusing, too, when it comes to figuring out how and where to sign up for the vaccine. The county is still not vaccinating teachers even though the state has said that they must. We’ve had teachers sign up for and go to county vaccination sites thinking they were eligible only to find out that they weren’t—the county is still only vaccinating 1A (first responders) and residents 75 or over. The state, on the other hand, is vaccinating teachers, and there are separate sites (particularly Holy Cross and Adventist Hospitals) that the state is using to vaccinate Montgomery County residents. And now the Feds are getting into it. The federal government is offering vaccines to state residents who fit current state eligibility requirements through chain pharmacies like CVS and Walgreens. Three different levels of government, all offering vaccines but not coordinating with one another in the signup, rollout, and distribution. A recipe for success!

And that’s the long and the short of it. The number of vaccinated teachers at Green Acres increases week by week, and at this point, my best guess is that roughly between a half and two-thirds of our staff have received at least the first dose. Several have received both doses. So we’re slowly, slowly headed in the right direction.

Tent progress is another story has been difficult. The county is slow to respond to our requests and has a number of hoops to jump through that we are coming to realize don’t seem to make the tents safer for students—it’s just a lot of red tape. We are pressing forward, but answers are difficult to come by, which makes it hard to pull the trigger when it comes to purchasing things we need to purchase. But we’re hopeful and working hard to make it happen. We are going to keep pressing, and hopefully we will soon get the answer we need to get those tents open.

Be well, stay safe, and have a great Presidents’ Day weekend!

Peter Klam

Apologies for not having a blog post last week—given that the positive metrical trends were continuing and the fact that I needed every moment of time to finish proofreading dozens of report cards, it seemed reasonable to skip a week. My plan is to continue posting blog posts once per week unless shifting conditions necessitate more frequent postings.

As with many things during the pandemic, the snow this week was a double-edged sword. On the one hand, it was great to have our first substantial snowstorm in nearly two years. The escapist winter play that it allowed our children was a welcome respite from the monotony of being homebound for so much of the time. On the other hand, for our 2nd, 5th, and 6th graders, who like the rest of school had a snow day and a virtual learning day on the two days that they were supposed to be on campus, it was a bitter blow because they missed their opportunity to see friends in person (masked and socially distanced, of course, but nevertheless…). We are thinking about ways to give them at least a social time on campus, and GASPA has been a big help with this. We know it is hard, and we genuinely want kids back at school, but Washington winters are what they are and we have to be fair and prudent when it comes to asking folks to be out on the roads. We know, for example, that some residential streets were not plowed or treated as of yesterday morning, which factored into our decision-making to forgo in-person learning. But it is important for you to know that we do care, and we are trying.

The snow has also ground our tent work to a temporary halt. We are waiting to finalize flooring and lighting so that it can be ordered and installed, but we want the county licensure team to approve our choices before we invest in them. As you can imagine, these things happen rather slowly. But I am hopeful we’ll get word this week or early next, at which point we will do the ordering and installation. Then it’s just a question of final approval.


And the metrics continue to move favorably. As you can see from just these two accompanying graphs, the cases per 100K students continues to shrink, as does the positivity rate. Last week, the cases per 100K passed the halfway threshold of the CDC’s “moderate risk in schools” category, and the positivity rate is just a tick over 5%. That puts the current positivity rate almost below the Montgomery County Schools threshold—thresholds that have proven quite conservative compared to most of the rest of the country. It is worth noting (though I won’t share the graphs today), that the virus continues to shrink in the community as indicated by both the rt rate (which is still lower than 1, indicating that each infected person passes the virus along to less than one other person on average), and the week-over-week percent change, which shows the virus’s presence diminishing for over two full weeks of the metric. Things are looking up!


And in case you are curious about what is happening with the vaccine, I started tracking that, too, yesterday. Unfortunately, the county does not show the daily history of vaccine distribution, so it will take me a couple of days to start to compile cumulative statistics as I take their daily data and include it in my spreadsheet. There are a few interesting nuggets to report at this point. First, it is interesting to note that the county’s reporting of doses received and administered is strikingly different than the state reports for Montgomery County. The county reports that only 29K doses have been administered, but the state-reported number Is nearly 70K. The only guess that I have is that many MoCo residents got their doses through other counties.

You might be aware that despite the governor’s remonstrations, Montgomery County is not yet opening up to vaccinate teachers. We are in the next group to be eligible, but right now they don’t have the doses available to us—only pre-registration. There are local entities, like Holy Cross Hospital, who are vaccinating teachers, but the demand is incredible—I heard a rumor that they had over 4000 people trying to sign up for 60 spots a week or so ago. At any rate, a rough statistic for the county based on my estimate of how many healthcare and first responders we have is that 26% of the eligible population (healthcare workers, first responders, and residents 75 years or over) has been vaccinated up until this point. So things are progressing slowly. As I include their daily updates in my own statistics, we will get a handle on how slowly—and whether they are ramping up at all. I will keep you posted next week.

Peter Klam

I am writing this, sitting in the AMP Building hallway, monitoring arts classes. I can hear the laughter coming from the art classroom as kids work on their projects and chat. It is a welcome sound and a welcome circumstance. We are fully on board with families who have made the choice to keep their kids at home for the time being. But being here reminds me that learning is fundamentally social, a tricky hurdle for teachers designing lessons in a virtual environment.

We are working hard in many areas. We continue to pursue deep and detailed information about our HVAC systems so that we can be as flexible as possible in scheduling spaces while maintaining a safe environment. We are also rounding the corner on tents. I’m sure that many of you have seen them set up on the field and in the courtyard. The last two steps are flooring and lighting—we’re close to purchasing those and getting them installed—and then it’s down to the county approval process. We don’t honestly know how long that will take, but they insist that they’ve tried to streamline the process so tents can go up during the pandemic. I envision that once we have all the pieces in place, they will approve us quickly. And we have circulated to families our semi-permanent schedule—permanent until we are ready to be back for full days, that is!


In terms of the metrics, things have been trending positively over the past week. You can see that the percent change finally made the turn and has been trending down for several days. This suggests that the presence of the virus is diminishing in our community. This impression is reinforced by our Rt—a measure of how many people each infected person infects. That number, below 1.0 for several days, suggests a diminishing presence in the community because each infected person is infecting fewer than one other person (I haven’t included that graph here, but you can find it on the Montgomery County COVID-19 Information Portal).


The positive cases per 100K has been in steady decline for over a week, and the positivity rate has been declining for two weeks. Now this doesn’t mean that all is safe and we can let our guard down. The temptation as metrics come down is to do just that—which is what can make them eventually rebound. And it’s good to remember that these metrics are coming down from high points that we hadn’t seen before during this pandemic. But declining metrics are a good thing, and as long as we are strong in our mitigation, we should be able to maintain a relatively safe in-person learning environment on campus. It also reinforces our decision to return.

Finally, it’s worth having a quick look at our internal statistics. As we mentioned in previous posts, we are focusing more intently on what is happening in our own community now that we are testing every week. Our results from this week should come out later today (after this post is published), but we have the data from last week, and it is quite favorable. The only positive test was a person who came down with COVID over the break, so the positive test was related to a previously-known case. There were no new cases for the week. The doctors have suggested that this person could continue to test positive for several weeks despite no longer being contagious, so it does not represent a new case or a growth in the virus’s presence in our campus community.