Great to see that air quality and the health impacts of fine dust getting more and more attention.
Talking about "smarter kids", we should not forget the impact of CO2 on cognitive performance.
In order to run air purifiers effectively you need to block outside air. This in turn will lead to a substantial increase in CO2. Last year we measured the CO2 development in a classroom and detected extremely high CO2 levels [1].
I am living in an area of high air pollution, and more and more people are starting to move away from standard air purifiers and install positive pressure fresh air systems [2] that take outside air, filter it and release it inside the house. Thereby keeping CO2 low and presenting dirty air from entering.
One of the reasons why many people install these systems is because they are getting more aware of the cognitive impacts of bad air.
I often see very high CO2 levels in bedrooms, which was also observed in the mini study https://www.mdpi.com/2076-3417/9/17/3533 , and the simple act of leaving the bedroom door open might presumably therefore improve sleep quality (https://onlinelibrary.wiley.com/doi/abs/10.1111/ina.12435) according to these small studies. But of course, adequate ventilation could make sure this isn't a problem regardless if the door is open or not.
Just to add to your point about the importance of ventilation, there are also VOCs (eg. from furniture off gassing and cleaning products) that HEPA filters can't do much about, and at least in my experience (which is a bit skewed due to only measuring with "cheap" sensors), active carbon filters only help for a short while. Other technologies, like photocatalytic air purification, seem to also have limited effect, and do in turn produce CO2 as they break down pollutants (I'm not sure how much though), which again means adequate ventilation is important. So having "control" over where air gets in to the building is very helpful indeed, as you can't get around needing an adequate air exchange.
You seem to know quite a bit about this already, but in case you or anyone else is curious, a few more articles:
Oh well can’t be helped now. I do have two air purifiers though. And my own measurement suggest they do have a pretty dramatic effect on PM levels.
Similarly cooking does indeed spike levels sky high. Some of it is deceptive though - I noticed that cooking that vents a lot of moisture (eg rice cooker) seems to affect readings too
"Under the conditions of the tap water humidification and the cold boiled water humidification, the mass concentration of particulate matters increases dramatically. But under the condition of the purified water humidification, particulate matters of each particle size have no obvious changes, and the mass concentration is lower."
The linked studies are about humidifiers, so perhaps different, but feels like for instance a rice cooker is not that far off. My gut feeling is that the particulate matter generated through "boiling water" is generally less dangerous than what you get from high-temperature frying (perhaps can depend on the water though). For instance based on https://www.nature.com/articles/s41586-020-2902-8 :
"We find that secondary inorganic components, crustal material and secondary biogenic organic aerosols control the mass concentration of particulate matter. By contrast, oxidative potential concentration is associated mostly with anthropogenic sources, in particular with fine-mode secondary organic aerosols largely from residential biomass burning and coarse-mode metals from vehicular non-exhaust emissions."
I'm not sure this is news to anyone. In Asia, I saw plenty of advertisements for air purifiers, googled the topic and bought one.
I'm guessing the main issue is that good ones are too expensive for many people, similar to how eating exclusively high quality food is too pricey for the average worker.
I get the impression that people in Asia (well, I only have limited experience of Shanghai and various cities in south-west Japan) are quite aware. I saw a lot of air purifiers (for instance in hotels) in Japan. And in Shanghai they showed PM2.5 predictions as part of the weather forecast. And I noticed that a lot of people know about formaldehyde (a specific chemical / VOC that can be problematic in indoor air). Although, an old guy I met in Shanghai told me "I don't really like air purifiers, you have to clean them all the time, I rather just open the window" ;)
But in Germany where I live, or Sweden where I'm from, few people I know ever thought about this. I suppose the air is just too good for people to bother thinking about it. But as observed in https://sciencenordic.com/chemistry-denmark-environment/our-... it might still be worth spending a few thoughts about it:
“Our indoor UFP levels are close to those in Beijing apartments but the pollution sources are completely reversed,” says Bekö, explaining that 70 percent of all UFPs in Beijing are from outdoor sources while in Denmark it’s the other way around.
(they looked at indoor pollution in Copenhagen, and UFP stands for ultrafine particles (here defined as "Ultrafine particles (UFPs) are particles with a diameter of less than 100 nanometres.", so kind of PM0.1))
I would be really happy if I could create low-cost air purifiers or DIY solutions (I have quite good success with a Pringles can made an air purifier to reduce PM2.5 ;) ). Not sure if that will happen, but, luckily others do it already: https://smartairfilters.com/
IKEA also have an air purifying curtain (https://www.ikea.com/us/en/rooms/living-room/how-to/purify-y...) at a decent price - but don't know how good it is and it won't work for particles, but just chemicals/gases. They recently also released an air purifier https://newsroom.inter.ikea.com/news/ikea-committed-to-make-... which is fairly cheap (49.99EUR/~60USD), especially the filter (HEPA H12) sticks out a bit to me just costing 4.99EUR (6USD) in Germany. Spontaneously, SmartAirFilters feels like a better choice for people that live where they sell it cheaply though.
You are still right of course, more money can give better stuff, and both IKEA and SmartAirFilters might still be way too expensive for many.
Talking about "smarter kids", we should not forget the impact of CO2 on cognitive performance.
In order to run air purifiers effectively you need to block outside air. This in turn will lead to a substantial increase in CO2. Last year we measured the CO2 development in a classroom and detected extremely high CO2 levels [1].
I am living in an area of high air pollution, and more and more people are starting to move away from standard air purifiers and install positive pressure fresh air systems [2] that take outside air, filter it and release it inside the house. Thereby keeping CO2 low and presenting dirty air from entering.
One of the reasons why many people install these systems is because they are getting more aware of the cognitive impacts of bad air.
[1] https://www.airgradient.com/blog/2020/02/07/we-measured-the-...
[2] https://www.airgradient.com/blog/2020/01/08/positive-pressur...