Rob - the implication is that you are not using a respirator mask that filters dust and VOCs (volatile organic compounds). I strongly recomment you get one, they are a lot cheaper and much less trouble than a lung transplant.
I use the 3M model 6200 like this - not sure if it's available in UK, but there will be an equivalent. LINK to Amazon. respirator mask, LINK to the dust/VOC cartridges. I like the type with replaceable cotton dust filters rather than the sealed units.