"How many purifiers is one person equivalent to? Put another way, if you have a purifier and a person in a room at the same time, are the particles mostly captured by the person or the machine? Because I've tested without turning on a purifier, and the numbers were close to when I turned on the purifier."
Reasons humans ARE purifiers
This logic is simple. If particles are getting stuck in our lungs, aren't humans actually air purifiers?
Reasons humans are NOT purifiers
But on the other hand, there are several reasons to think humans are NOT purifiers:
1. Outdoor air is constantly coming into our homes. So if there's an effect of breathing, it'd have to be very strong in order to overcome the constant influx of outdoor air.
2. Human breath will make the room more humid, and laser particle counters will count those water particles. (I've tested this by holding the Dylos next to a pot of boiling water. The numbers shoot up.)
3. Humans are constantly shedding skin cells that become dust in our homes. One estimate is that we lose 30,000-40,000 cells per hour.
Of course, that will depend on whether we're moving around or not. While we're in bed, a lot of those cells are kept under the sheets, but there will still be cells from our head and arms (if they're not underneath the covers).
What does the data say?
I didn't set out to test this question, but during Gus's 200-day HEPA longevity test and his more recent tests, there were two days where he forgot to turn on his purifier. Here's what happened to the .5 micron particles in his room on a day where outdoor AQI was relatively stable:
Reasons humans ARE purifiers
This logic is simple. If particles are getting stuck in our lungs, aren't humans actually air purifiers?
Reasons humans are NOT purifiers
But on the other hand, there are several reasons to think humans are NOT purifiers:
1. Outdoor air is constantly coming into our homes. So if there's an effect of breathing, it'd have to be very strong in order to overcome the constant influx of outdoor air.
2. Human breath will make the room more humid, and laser particle counters will count those water particles. (I've tested this by holding the Dylos next to a pot of boiling water. The numbers shoot up.)
3. Humans are constantly shedding skin cells that become dust in our homes. One estimate is that we lose 30,000-40,000 cells per hour.
Of course, that will depend on whether we're moving around or not. While we're in bed, a lot of those cells are kept under the sheets, but there will still be cells from our head and arms (if they're not underneath the covers).
What does the data say?
I didn't set out to test this question, but during Gus's 200-day HEPA longevity test and his more recent tests, there were two days where he forgot to turn on his purifier. Here's what happened to the .5 micron particles in his room on a day where outdoor AQI was relatively stable:
There doesn't seem to be an effect of having Gus in the room. In fact, particulate increased for about 5 hours after he went to bed (although there was a decrease right before he woke up).
On the other test day, outdoor AQI went up while Gus slept:
On the other test day, outdoor AQI went up while Gus slept:
Indoor particulate increased after Gus went to bed, with a time lag between the US Embassy datapoints and Gus's datapoints.
These are only two tests, but at the very least we can rule out a strong effect of human breathing. Humans are not making the air significantly cleaner.
What about large particles?
The Dylos also tests for larger particles--particles 2.5 microns and above. These might be easier for Gus to purify.
At the same time, these large particles are also more likely to be affected by Gus closing his door at night. That's because these are larger particles are more likely to settle on the ground when the door is closed and air is not flowing as much (and no one is moving around in the room, kicking up dust). Unfortunately, with this test, we can't separate the effect of closing the door and Gus breathing. But here's what happened:
These are only two tests, but at the very least we can rule out a strong effect of human breathing. Humans are not making the air significantly cleaner.
What about large particles?
The Dylos also tests for larger particles--particles 2.5 microns and above. These might be easier for Gus to purify.
At the same time, these large particles are also more likely to be affected by Gus closing his door at night. That's because these are larger particles are more likely to settle on the ground when the door is closed and air is not flowing as much (and no one is moving around in the room, kicking up dust). Unfortunately, with this test, we can't separate the effect of closing the door and Gus breathing. But here's what happened:
The large particles seem to go down a bit. (That large spike might have been Gus getting up to go to the bathroom.)
Here's what happened on the other test day:
Here's what happened on the other test day:
On the second test day, there seems to be a slight down-trend, but it goes up when outdoor air gets dirtier.
Do purifiers still have the same effect with no people in the room?
A second way to answer this person's question is to do tests with no people in the room. If human breathing is contributing a lot to cleaning the air in the room, the results should be worse if we do tests without humans in the room.
Fortunately, I have lots of those tests, including six straight days of tests with a Cannon set on a timer to turn on for two hours every day. I was on vacation at the time, so no humans set foot in the apartment. Here's what I found when I came back:
Do purifiers still have the same effect with no people in the room?
A second way to answer this person's question is to do tests with no people in the room. If human breathing is contributing a lot to cleaning the air in the room, the results should be worse if we do tests without humans in the room.
Fortunately, I have lots of those tests, including six straight days of tests with a Cannon set on a timer to turn on for two hours every day. I was on vacation at the time, so no humans set foot in the apartment. Here's what I found when I came back:
Conclusion
1. Purifier effects are not getting an artificial boost from having humans breathing in the room.
2. Preliminary data shows that humans are not air purifiers (although there may be an effect on the largest particles).
1. Purifier effects are not getting an artificial boost from having humans breathing in the room.
2. Preliminary data shows that humans are not air purifiers (although there may be an effect on the largest particles).