Discussions on this subject focus on size, but a thing I don’t see discussed is whether type of particle matters.
Intuitively, it seems that a droplet of water (cue aromatherapy diffuser article) is biomechanically different from a particle of soot, but my knowledge takes a sharp cliff dive there.
Maybe since in aggregate, the types of particles in these size ranges are usually bad (tire dust, wood soot…) so its kind of irrelevant for most discussions 🤷
Definitely the type of particle matters! (Proof: Asbestos.) But we don't seem to be able to say much firm beyond that at the moment. Even our understanding of the mechanism by which particles cause harm is fairly shaky. "They make their way through the lungs into the body and then... activate the immune system, or something?"
In order for this idea to work you couldn’t use plug in the wall air purifiers. You need to have whole house air purifiers running through ducting. And the typical house is not airtight at all. Even Passive House certified structures only have to meet a 0.6 air changes per hour at 50 pascals standard.
To deal with both increasing energy costs and polluted air the Passive House standard would be great. In addition to air tightness and mechanical ventilation, it includes thick thick insulation around the entire conditioned space. Ventilation uses energy recovery ventilators with full filtration because you’re effectively living in a more or less airtight beer cooler.
I don’t think that the kind of air purifiers that are sold for domestic use at electronic stores have enough capacity in terms of cubic meters per minute. But the bigger problem is that you need to separate the extraction and the input in order to get the entire volume of the air in the house to change over. Otherwise you just have a closed loop blowing air through a small area of a room. In general, extraction is done from the kitchen and toilet/bath rooms, while input is into the bedrooms, but this depends on the house design. This kind of system requires ducting in the ceilings.
The effectiveness of ventilation filtering system is easy to check by using incense. If your ventilation doesn’t seem to be decreasing the odor, it’s not really doing anything.
Thanks for this great math exercise on the potential health benefits of buying everyone air purifiers. I initially followed this newsletter because of a post on air quality. I think one glaringly obvious variable that was not included in this essay was the health benefit of decreasing the incidence of airborne diseases such as flu, measles, tuberculosis, and especially COVID-19.
Considering that homes were the most likely source of COVID-19 infections for individuals (at least earlier in the pandemic - because people got sick elsewhere and then came home and shared air with their housemates) it seems reasonable that homes are also the most likely source of other airborne diseases. Air purifiers in each home would likely decrease the number of individuals who get infected from most airborne diseases, or at least the severity of the infection. I have to believe that decrease provides a substantial boost in terms of dollars / DALY.
Given the heavy impact of airborne diseases on individual health, a seemingly much better alternative to buying every home a purifier would be investing in clean air in shared public spaces. While for any individual the home is the most likely source of infection for airborne diseases, it is certain public spaces where people from multiple households congregate that the disease really gains momentum and allows for mass infection of the population. To emphasize this point, a study published in JAMA Network Open suggested that 70% of household COVID-19 transmissions originated with a child, and it is reasonable to assume that most of those infections came from school or daycare. Without public transmission, each home would be where the chain of transmission was ultimately broken.
Imagine if all those hypothetical air purifiers were instead put in public spaces where people from multiple households congregate? They could have a powerful effect on limiting transmission in schools, healthcare facilities, prisons, and workplaces, which would drive community transmission downward. In the school I run, Abrome, we put air purifiers in every room, bringing each room above 12 air changes per hour in filtration alone. Thanks in part to our air filtration efforts, we never had a case of COVID transmission in our school (although we used a multilayered approach which also decreased the likelihood of COVID entering into the space in the first place). Considering that 70% of household COVID-19 transmissions originated with a child, I have to believe that our efforts alone provided real benefit to DALYs of our local community. We could do the same for all schools, daycares, and workplaces.
In addition I think there is also a psychological effect (that is hard to measure) and that is that people perceive that the air is cleaner when there is an air purifier in the room.
Which may lead to an overall better feeling and mental health state. For example: when an air purifier is placed in the bedroom, people may have the feeling that the room is more serene which can help people falling asleep better. Better sleep is better mental health. Better mental health can lead to a better quality of life and even a longer life.
Ironic, considering the push to do nothing to stop the spread of airborne disease over the past four years was often justified because of amorphous mental health concerns.
Totally agree that burden of disease would be great to consider (though modeling this is tricky) and also that purifiers would likely have a higher ROI if used in public places. (I find the lack of purifiers in subways particularly frustrating—though people will quote hilarious prices like $X,000,000 to install purifiers in *one* subway station in New York, so unless you assume some way to make the political problems leading to those costs go away, the ROI might not actually be as high as you'd think...)
I have a no-name white label monitor that I got second hand from a friend. It looks very similar to lots of ones you can find on aliexpress under similar brands. But I don't particularly trust it! I also use the IKEA VINDRIKTNING to check for air quality, even though it only has three levels and independent tests suggest it can vary from those levels by a factor of two. (I still figure it's useful for knowing if I've created particles in the kitchen.)
Once you take into the account that the elastic part of electricity production is obtained, and will contonue to be for at least another 40 years, by burning fossil fuels, it becomes even less viable.
I can survive a day or a week or a month of seasonal allergies, but my activities are significantly curtailed. We could probably save hundreds of lives a year with what I spend on allergy mitigations, but my life would be significantly poorer.
My point of view is extremely biased towards my own welfare, but it's the only point of view I've got
If you can afford to spend that much money on allergy mitigations, you'd still probably want to do that even from a purely altruistic perspective since not mitigating the allergies would impede your ability to contribute to the world!
So, thinking about this a bit more: What if we made a subsidy available for people who felt like they would benefit from air purifiers? It's not an all or nothing question.
Can you please blog about germicidal UV radiation? Ideally, with a description of bolting it onto a HEPA box fan to capture UV's ozone byproducts :) https://www.vox.com/the-highlight/23972651/ultraviolet-disinfection-germicide-far-uv
Discussions on this subject focus on size, but a thing I don’t see discussed is whether type of particle matters.
Intuitively, it seems that a droplet of water (cue aromatherapy diffuser article) is biomechanically different from a particle of soot, but my knowledge takes a sharp cliff dive there.
Maybe since in aggregate, the types of particles in these size ranges are usually bad (tire dust, wood soot…) so its kind of irrelevant for most discussions 🤷
Definitely the type of particle matters! (Proof: Asbestos.) But we don't seem to be able to say much firm beyond that at the moment. Even our understanding of the mechanism by which particles cause harm is fairly shaky. "They make their way through the lungs into the body and then... activate the immune system, or something?"
In order for this idea to work you couldn’t use plug in the wall air purifiers. You need to have whole house air purifiers running through ducting. And the typical house is not airtight at all. Even Passive House certified structures only have to meet a 0.6 air changes per hour at 50 pascals standard.
To deal with both increasing energy costs and polluted air the Passive House standard would be great. In addition to air tightness and mechanical ventilation, it includes thick thick insulation around the entire conditioned space. Ventilation uses energy recovery ventilators with full filtration because you’re effectively living in a more or less airtight beer cooler.
What's the argument that you couldn't use freestanding air purifiers?
I don’t think that the kind of air purifiers that are sold for domestic use at electronic stores have enough capacity in terms of cubic meters per minute. But the bigger problem is that you need to separate the extraction and the input in order to get the entire volume of the air in the house to change over. Otherwise you just have a closed loop blowing air through a small area of a room. In general, extraction is done from the kitchen and toilet/bath rooms, while input is into the bedrooms, but this depends on the house design. This kind of system requires ducting in the ceilings.
The effectiveness of ventilation filtering system is easy to check by using incense. If your ventilation doesn’t seem to be decreasing the odor, it’s not really doing anything.
Thanks for this great math exercise on the potential health benefits of buying everyone air purifiers. I initially followed this newsletter because of a post on air quality. I think one glaringly obvious variable that was not included in this essay was the health benefit of decreasing the incidence of airborne diseases such as flu, measles, tuberculosis, and especially COVID-19.
Considering that homes were the most likely source of COVID-19 infections for individuals (at least earlier in the pandemic - because people got sick elsewhere and then came home and shared air with their housemates) it seems reasonable that homes are also the most likely source of other airborne diseases. Air purifiers in each home would likely decrease the number of individuals who get infected from most airborne diseases, or at least the severity of the infection. I have to believe that decrease provides a substantial boost in terms of dollars / DALY.
Given the heavy impact of airborne diseases on individual health, a seemingly much better alternative to buying every home a purifier would be investing in clean air in shared public spaces. While for any individual the home is the most likely source of infection for airborne diseases, it is certain public spaces where people from multiple households congregate that the disease really gains momentum and allows for mass infection of the population. To emphasize this point, a study published in JAMA Network Open suggested that 70% of household COVID-19 transmissions originated with a child, and it is reasonable to assume that most of those infections came from school or daycare. Without public transmission, each home would be where the chain of transmission was ultimately broken.
Imagine if all those hypothetical air purifiers were instead put in public spaces where people from multiple households congregate? They could have a powerful effect on limiting transmission in schools, healthcare facilities, prisons, and workplaces, which would drive community transmission downward. In the school I run, Abrome, we put air purifiers in every room, bringing each room above 12 air changes per hour in filtration alone. Thanks in part to our air filtration efforts, we never had a case of COVID transmission in our school (although we used a multilayered approach which also decreased the likelihood of COVID entering into the space in the first place). Considering that 70% of household COVID-19 transmissions originated with a child, I have to believe that our efforts alone provided real benefit to DALYs of our local community. We could do the same for all schools, daycares, and workplaces.
In addition I think there is also a psychological effect (that is hard to measure) and that is that people perceive that the air is cleaner when there is an air purifier in the room.
Which may lead to an overall better feeling and mental health state. For example: when an air purifier is placed in the bedroom, people may have the feeling that the room is more serene which can help people falling asleep better. Better sleep is better mental health. Better mental health can lead to a better quality of life and even a longer life.
Ironic, considering the push to do nothing to stop the spread of airborne disease over the past four years was often justified because of amorphous mental health concerns.
Totally agree that burden of disease would be great to consider (though modeling this is tricky) and also that purifiers would likely have a higher ROI if used in public places. (I find the lack of purifiers in subways particularly frustrating—though people will quote hilarious prices like $X,000,000 to install purifiers in *one* subway station in New York, so unless you assume some way to make the political problems leading to those costs go away, the ROI might not actually be as high as you'd think...)
That’s it right there--the political costs outweigh the financial costs of doing something. Sad but true.
Do you use an air purity/particulate meter to check the quality of your home air? Any recommendations on that if so?
I use a couple Atmotube units to do this. When I was shopping, they were the one of the best quality-sensitivity-for-price units.
I have a no-name white label monitor that I got second hand from a friend. It looks very similar to lots of ones you can find on aliexpress under similar brands. But I don't particularly trust it! I also use the IKEA VINDRIKTNING to check for air quality, even though it only has three levels and independent tests suggest it can vary from those levels by a factor of two. (I still figure it's useful for knowing if I've created particles in the kitchen.)
Once you take into the account that the elastic part of electricity production is obtained, and will contonue to be for at least another 40 years, by burning fossil fuels, it becomes even less viable.
I can survive a day or a week or a month of seasonal allergies, but my activities are significantly curtailed. We could probably save hundreds of lives a year with what I spend on allergy mitigations, but my life would be significantly poorer.
My point of view is extremely biased towards my own welfare, but it's the only point of view I've got
If you can afford to spend that much money on allergy mitigations, you'd still probably want to do that even from a purely altruistic perspective since not mitigating the allergies would impede your ability to contribute to the world!
So, thinking about this a bit more: What if we made a subsidy available for people who felt like they would benefit from air purifiers? It's not an all or nothing question.
Yeah, I think better targeting could probably improve the ROI quite a bit—my intuition is maybe by 3x? Or 5x?