One is the excessive use of solvent-based chemical treatments in houses for rising damp. As an architect, I keep coming across situations where surveyors are covering themselves against any claim by saying that chemical treatments may be advisable. This is then changed by ill-informed mortgage lenders into an imperative: "We will not give you a mortgage unless this treatment is carried out."
This often results in multiple treatments, one each time a property changes hands. The time will come when substantial claims will be made against mortgage lenders for insisting on unnecessary treatments that may have damaged peoples' health.
The second possible cause is the aggressive perfumes that manufacturers of household detergents, cleaners, polishes and so on add to their products in the mistaken belief that we need to be able to smell them to know that they are working. These nasty smells are getting worse all the time as manufacturers constantly tweak their products.
I used to visit a house where a teenager suffered badly from asthma. Every time I crossed the threshold I was met by a strong blast of fabric softener.
PATRICIA A TUTT
Peel, Isle of Man