Sorry I posted the photos without discription so Ill be adding them in this comment. 
basically as the photo shows, i get a sudden peak of super bad air quality for a 2 hour window whilst I was asleep with the windows closed. 
 

how is this peak explained and what could have caused it? Surely it couldnt be a temporary lethal air quality that was present for a block of 2 hours and went away.

any ideas? Much appreciated!

Hi @Exterious 

It looks like your air quality built up and reduced over a 3 hour period.

My first guess would that something in your house has caused this or something from the outside is getting in and the purifier is picking it up. 

I’ve found two articles that can help you.

I don’t think there is anything to worry about. 

Hope this helps :)

Pete