Noticed a commercial over the weekend a Rx allergy prescription commercial came on. The one where the actor doctor gives actor patient advice at the end. I`m not sure if you saw it but, at the end the doctor said "If your prone to allergies where a dust mask when vacuuming."
So, it sure does sound like good advice. If you are doing residential or commercial. You have no idea what is in the carpet. Even if your using a good HEPA vacuum I`m sure there are particles in the air being released. Many residential customers , if your using their vacuum you probably have no idea what has been sucked up in that vacuum. If you or your staff would wear a mask, the exposure to whatever contaminants would be minimized or eliminated.
It may cause a bit of concern to commercial customers if your account is open while cleaning, or if your residential customer is home. If there is no customers there, I really can`t see a problem.
Even if there was customers there, you or your staff could explain concern about allergens in carpet.
A good explanation of why masks are worn, just might lead to the sale of extra carpet cleaning.