We experienced a similar fog at the Four Seasons Resort Langkawi. They notified us on check-in about it.

My wife and I are both medical practitioners - neither of us were worried about it as you would have to consume large quantities of the chemical to be affected by it. It is very unlikely that it caused your husband's rash, so I really wouldn't be too concerned by it, however, your husband should probably see a dermatologist and find out the actual cause.