Purifier - PM2.5/PM10 Elevated but only at night | Dyson Community
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Since getting our Dyson TP07 I’ve become fascinated observing the formerly invisible world of air pollutants inside our home. Some observations are easily explained (such as increased levels after frying food) but I’m at a loss as to explain why our PM2.5 and PM10 levels increase every evening before going back to normal in the morning. We run the unit in automatic and it will kick all the way up to 10 for the whole night before going back to 2 or 3 in the morning.

The unit is in our living room. We are in a single family home. It is currently winter so the windows are closed all the time. The only thing that happens at night compared to the day is our thermostat automatically decreases the temperature at night. 18C (64F) at night vs 22C (72F) during the day. The furnace fan is set to run continuously (runs even when the furnace is off). The only change at night is the air temperature.

Is it possible that the change in air temperature could affect the accuracy of the pollution sensors? I don’t see how the inside air temperature could affect the ‘actual’ level of pollution in the air.

 

 

Hi @sanger

It really is fascinating. It’s to a kin of a hidden world, one which Dyson has present to its owners. Sensing, recording, and structuring the data in which a way that it builds even more intrigue. Sometimes where none may have existing prior to becoming an owner. Purification has slowly become a hobby of mine since owning the DP04. The Community has helped grow this knowledge and I’ve looked to share this insight with others. This is of course where the chance presents itself.

If I can make a one suggestion, that is to first understand the different particles the purifier can detect. I found this article very insightful in that respect (What are the common household pollutants? | Dyson Community). This states that ‘Smoke, industrial emissions and the gasses produced by burning candles all emit PM2.5’. 

At first glace, I believe the issue is one that is in plain sight. The furnace fan. It seems to me that the Purifier is detecting emissions and recoding them as a minimal increase in the home.

Another cause, noticeable less likely, is that it could simply be explained by nocturnal emissions. Without going into too detail here, as we sleep our body produce gasses. These may be being detected and the Purifiers Auto function is reacting. 

Other than these two points, the ‘What is off gassing and what causes it? | Dyson Community’ article helped me understand what else in my home could be omitting emissions, without the common signs. It could also help you to an answer.

David. 


@DavidTaylor your thought was mine as well; I would think that your furnace fan is contributing to the air quality readings on your device. Especially if you have an air filter in the furnace, if that’s being used less, that could be affecting the air quality in your home, and the really cool thing is (at least I think it’s cool), you likely would never have known that, prior to getting your Dyson and seeing in real-time how fluctuations in the home, with things such as furnace use, can change the air quality of the air we breathe day in and day out. I may be completely off base, but that sounds like the most logical explanation of what you’re seeing in your air quality readings. 


I knew it wasn’t the furnace fan because the fan is set to run 24/7 regardless of whether the furnace is heating or not (we have a 3 story home and running the fan non-stop helps with the temperature gradient between the top and bottom floors).

I think we may have found the culprit. My wife uses a cool-mist humidifier at night. Unlike a regular steam mister the cool-mist generates fine water droplets using a vibrating piezoelectric crystal. Since the cool-mist doesn’t “evaporate” the water to make the mist the water droplet are emitted with calcium and other minerals still in the water. As the droplets evaporate they release the calcium into the air as a very fine calcium power. The mister is on the 3rd floor and the Dyson is on the first but it looks like those fine particles make their way throughout the house.

 


Hello @sanger, Aha! i will be perfectly honest with you, that never even crossed my mind. You may want to try distilled water in your humidifier to see if that makes any difference. I know with Dyson branded humidifiers, when using in conjunction with a purifier in the home, that’s generally our recommendation.


Interested to know if this was, indeed, the root cause? 
 

we’ve had our purifier for several years and only the last three days we have had the exact same experience. 
 

around 0230 - 0400 we get spikes on the Pm2.5 and Pm10 graphs , varying numbers of spikes right through to 0730. Hitting purple!

 

daytime the graph is green and flat. 
 

We don’t have any humidifiers. 
 

the only change (and I’ll admit to this one), is for the first time in 3 years I bought filters from another online source (not the cheapest available, but cheaper than the £60 Dyson ask). 
 

I’m wondering if it’s the different filters causing this? 
 

any thoughts? 


Yes, the cool mist humidifier was the root cause. If we don’t run it we don’t get the spike.


Interested to know if this was, indeed, the root cause? 
 

we’ve had our purifier for several years and only the last three days we have had the exact same experience. 
 

around 0230 - 0400 we get spikes on the Pm2.5 and Pm10 graphs , varying numbers of spikes right through to 0730. Hitting purple!

 

daytime the graph is green and flat. 
 

We don’t have any humidifiers. 
 

the only change (and I’ll admit to this one), is for the first time in 3 years I bought filters from another online source (not the cheapest available, but cheaper than the £60 Dyson ask). 
 

I’m wondering if it’s the different filters causing this? 
 

any thoughts? 

Filters are a good place to start. They could have inferior materials or be extruding whatever's being detected. The non-genuine filter on my cordless vacuum didn’t react well. 

According to What are the common household pollutants? PM2.5 are smoke, industrial emissions and burning candles, and PM10 is pollen and allergens.

Could any of these be detectable at these times? Do you leave a window open for example, live next to a road, an industrial unit or have someone that smokes outside the home? If no to all these, try giving the machine a service/clean. The CM shared this post a while back Keeping your purifier performing at its best.

It would be great to here is this was the cause.