Huge spike in VOC levels shortly AFTER airing the room. Any suggestions? | Dyson Community

Huge spike in VOC levels shortly AFTER airing the room. Any suggestions?

  • 23 October 2023
  • 3 replies

Hello all,

Trying to get my head around something that is happening in our newly built garden room. 

There is a huge spike in VOC levels after closing the door to outside, that goes from good all the way up to very poor within an hour, then slowly comes down over the next few days back to good. Once it is back down to green, it will stay like this for days until the door is opened again, the fresh air from outside comes in and the VOCs drop to absolutely nothing, but as soon as the door closes there is a huge spike again which. 

I cannot see the logic in why this is happening. There are a lot of things which could be off gassing, lots of adhesive and glue used in the construction of the room, but I cannot fathom why the huge spike is only noticeable immediately after letting fresh air circulate for a few hours. My only theory is maybe the VOCs are not being cleared in the whole room by the Dyson, only very locally to the machine and when the air from outside circulates it moves any vapours around and the machine can pick them up again? 

There is NO ventilation currently, soon to be fitting MVHR.


Any thoughts welcome. (Have tried to attach a screen grab to aid but seems to keep failing)




Best answer by DavidTaylor 24 October 2023, 09:56

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3 replies

@Ben_London Hi Ben, sounds like an interesting question. I can only speculate also. My guess is perhaps when you close the door from outside, it brings in some of the outdoor pollutants to the indoor space - say, pollen or dirt in the air?



Thanks Adam,

I don’t think that is it. Very shortly after when the door is opened the VOC and HCHO reduce dramatically almost to zero, but the PM and NO rise considerably. Concluding that the outdoor air has more particulate matter, being in London. Once the door is closed the VOC just shoots up to the red zone over an hour, then takes a day or to come down, unless the door is opened again then it will reduce but rise again as soon as it is closed. It is quite odd. I’m sure the VOC must be coming from the inside and something used during construction, but cannot fathom why it is the exposure to the fresh air that seems to make it spike to suddenly. I am soon to add mechanical ventilation with heat recovery and hoping that will reduce the VOC levels. 



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Hi @Ben_London

I believe the response on the Formaldehyde Cool Purifier doesn't improve air quality especially VOCs post might have some bearing here. 

I suggest reading the two articles below for further context on the VOC source and the potential for Off-gassing. 

(1) What are the common household pollutants? | Dyson Community

(2) What is off gassing and what causes it? | Dyson Community