#covidco2
Hairdressers and barbers were allowed to open in Ireland last week, so I lent a CO2 monitor to my friend Nora, who runs a hairdressing salon in Cork city.
The monitor (circled in red) was placed in the middle, unused station, 1-2 m from the chairs.
1/
I gave Nora some simple advice - keep a window open and increase ventilation if the CO2 level rises above 800 ppm.
Results from Day 1 show levels rise to around 800 ppm even with window open.
When Nora noticed this she opened the door slightly and the CO2 dropped rapidly.
2/
Results from Day 2 are very similar.
The window was always open, but CO2 levels only drop when the door is also opened.
This shows the importance of cross ventilation for clearing the air.
Open doors and windows that are opposite to each other to ensure a flow of air.
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This simple demonstration shows how CO2 monitors can be used to inform occupants when they should increase ventilation by opening more windows/doors.
Thanks Nora!
Ventilation reduces the risk of spreading COVID-19 because it flushes the virus out of the indoor air.
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As the reopening of businesses and workplaces moves forward, employers, employees and customers should make sure that ALL occupied indoor spaces are well ventilated.
We used an Aranet4 monitor in these tests, which costs €200 directly from the manufacturer. I like it because it uses a reliable NDIR sensor, has a clear display, decent app and is portable.
There are many other NDIR sensors on the market: drive.google.com/file/d/1PCQohZ…
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Pleased to see this important update to the Irish Government's Work Safely Protocol.
The section on ventilation is greatly enhanced and includes additional advice on HVAC systems, use of CO2 monitors and filtration. enterprise.gov.ie/en/News-And-Ev…
These cases studies of virus spread in Ireland have been reported on and commented by @ZaraKing@newschambers@Orla_Hegarty@DeeGilhawley among others. Good to see this type of analysis but what about aerosols? - the elephant in the room!...short thread.
Spread in houses - probably caused by close-range transmission. NPHET need to emphasise that distancing AND ventilation is essential, even in small indoor gatherings of up to 6 people. Open doors and windows regularly to clear the air.
Spread in bars/restaurants - distancing was observed, so it has to be longer range (>2 m) transmission by aerosols. Was the restaurant poorly ventilated? Four workers infected, even though close-contact time minimized. Key question - did workers wear masks or face shields?
Big development in USA as the Center for Disease Prevention and Control acknowledges that exhaled aerosols play a major and possibly dominant role in transmission of coronavirus. latimes.com/world-nation/s…
Side by side comparison of new and old guidance from CDC...
Congratulations to the aerosol scientists and indoor air quality experts in USA who have worked tirelessly for agency recognition of aerosol transmission. Now we need the European CDC and WHO to move in the same direction.
First measures introduced on 12 March had no major impact on air pollution. But more severe travel restrictions from 28 March have led to reductions of 47% in average NO2 concentration and 32% for PM2.5 compared to previous years.
NO2 data is very consistent - check out the average diurnal profiles for Quarter 1 (Jan-Mar) in 2018, 2019 and 2020. Remarkably similar! Morning peak due to vehicle emissions, evening peak due to combination of vehicles and solid fuel burning