UK schools receive 300k CO2 monitors in gov initiative to reduce COVID19 spread
imperial.ac.uk
imperial.ac.uk
A big problem with DIY projects is that most of the sensors have a built-on, on-by-default auto calibration function, which assumes it will consistently see fresh air for ~1h per day (or other period), which isn't always the case in an environment that doesn't have commercial HVAC (like a house or small school).
When the assumption is broken, the calibration is too and the data are close to useless as absolute measurements (they still have some small value as relative measurements).
The assumption that a fresh air baseline will always be seen is particularly easy to break right now. It's winter, so you're less likely to open the windows and due to COVID, you may be working from home, leaving very little time for CO2 to disperse.
[0]: https://www.coschools.org.uk/resources/RP24.4%20How%20to%20U...
Better use a sensor like the Senseair S8 that only calibrates every 8 days and you most likely have a weekend of low occupancy that should bring CO2 down to ambient levels.
But yes, the default is autocalibration. But honestly, the difference isn't that bad, it's probably like 100ppm offset for stale room air from outside, and 100 doesn't make a huge difference when you are trying to measure around 1500.
The article mentions that in passing: “As well as being a good ‘proxy’ for ventilation, lower CO2 levels have been linked to improved learning outcomes and better cogitative performance.”
I’d rather have fixed sensors so that they would stay, but these are portable and I imagine most will be left in a drawer after the pandemic goes away: «The portability of the CO2 monitors, supplied by the Department for Education (DfE), means schools can move them around to test different areas, starting with those they suspect may be poorly ventilated.»
At least the air cleaners might stay («distributing between 7,000 and 8,000 air cleaning units.») and I hope the CO₂ monitors will keep being used once people see the difference.
Presumably, 300,000 CO2 monitors is in the right range for one per classroom? Is ten classrooms per school a reasonable average?
It would make more sense to me to send 7-8k of them to say London schools than 20k to country schools.
Seems a bit tough to ever make them practical without central AC though, which is not common (nor any AC) in the UK.
I think it's the deep malaise of UK politics that they just hate spending money on anything, even if it will save far more money in the future. It's why the UK has the GDP-per-capita of Japan, but mostly looks like Serbia.
That sounds low: a secondary school with no sixth-form will have students in 5 different year groups, and will typically have more than two classes per year group.
That's 335,032 classes, and thus at least 335k classrooms (add extra ones for specialist classrooms)
However that number includes private schools. Remove those and you're looking at 8.3 million, with a larger class size, so potentially just 277k classes assuming 30 people per room (plus specialist classrooms like IT, Art, D+T, PE, etc)
https://explore-education-statistics.service.gov.uk/find-sta...
Headcount 8,911,853 Number of schools 24,413 Average class size 26.6
So 335000 classes
that's just England, which is 83% of uk, so 402000 classes total
It shows the current CO2 levels with a large green, yellow red LED matrix.
The kit comes with a custom PCB and 3D printable enclosure and is completely open source and open hardware.
It uses the Senseair S8 NDIR sensor that we made really good experience with and can be programmed with the Arduino environment.
More than happy to help any school (or anybody else) who wants to build these.
Better (but more expensive) would be monitors that could measure PM2.5 molecules in the air like that of the airborne aerosols that transmit Covid (phlegm, spittle etc).
https://www.medrxiv.org/content/10.1101/2022.01.08.22268944v...
Opening the windows will reduce CO2 but increase PM2.5. Not opening will lead to lower PM2.5 but high CO2.
Here in Asia in highly polluted areas, positive pressure systems are getting more and more popular at home as well as in classrooms[1].
[1] https://www.airgradient.com/resources/positive-pressure-syst...
> UK schools have received more than 300,000 CO2 monitors as part of a government initiative to reduce COVID-19 spread in classrooms
Actual title that I skipped because I thought the subtitle was more informative:
> Curbing COVID-19 in schools: Imperial scientists support CO2 monitor rollout
Happy to edit (while I can) if people disagree..
[0] - BBC News - https://www.bbc.co.uk/news/uk-northern-ireland-58790302
[1] - Scottish Parliament Report - https://www.parliament.scot/chamber-and-committees/committee...
[2] - Scottish COVID guidance for schools - https://education.gov.scot/media/ttkbrnde/reducing-risks-in-...
(edited to break up the links)
The CO2 levels in my office at home are ~400ppm at night, but head past 900ppm during the day. I'm going to add another alert to remind us to open windows! Although our townhouse is part of a back to back block, so only has windows on one side.
^Great and accessible write up on the misconceptions of aerosol transmission and droplets.
EDIT; being downvoted for sharing what is actually happening on the ground
Lack of ventilation plays a big role on the spread
A more robust air purification and ventilation system is what's actually needed, but good luck getting the Government to fund that, especially with the age and general run-down state of many of the UKs schools.
For what it's worth, you're probably being down-voted because you presented no evidence or context, rather than for the message itself.
Given how expensive the pandemic has been, I wonder if they might actually do this at some point. If covid doesn't just fade away it's probably one of the most effective things they could do to lessen the impact.
Taxation also causes all sorts of other issues since a large percentage of the population don't pay tax (or much tax), so then there are issues of fairness. Add it to VAT? Income tax? Corporation tax?
The people who work on school renovations earn money and spend it into the economy. Lots of people will earn more because of it. The only downside is that some private projects will be delayed or scrapped because people are working on school renovations instead. That's the actual cost of public projects.
It's never a matter of money. Only ever a matter of alternative uses for the effort of real people.
Virus particles are everywhere. There is no avoiding them.
Also, if the kids are wearing masks then the cognitive benefits go out the window with CO2 concentration being above 20,000ppm.
In other words, I don't care what the CO2 concentration is in my mask. I care what the average concentration is in each inhaled breath, which consists of the stale air in my mask, combined with the (presumably larger volume of) fresh air that is introduced by breathing in. I doubt the study methodology properly captured that.
1- the beneficial level in the article is to keep CO2 under 800ppm for learning benefit.
2- tidal volume in adults is 400-500ml.
3- volume inside an N95 varies based on model and face geometry, but is presumably 20ml or much larger, especially for children with smaller faces.
4- indoor CO2 concentrations are typically not lower than 600ppm.
Based on this info, average concentration easily exceeds 1000ppm. This is even more likely for children who have smaller tidal volumes and presumably more volume under the mask.
Out of curiosity, just looked at my PPM monitor behind my laptop... it reads 600 :) We have a good ventilation here. But humidity suffers (very low)
This will allow energy savings and maintain an optimum level of CO2 in the classrooms.
We often see big differences in our data comparing different classroom sizes, age of students and activities inside the classroom. So often a fixed hvac setting is not the best solution.
That may be the best greenfield solution. Yet this is not a greenfield situation. These sensors are assigned to the school, but they are not permanently installed, and they cannot control the systems. Most existing systems aren't even capable of being controlled that way.
Students are wearing them literally all day