[Speedslug]

You could have a problem and not know it Patsy.

The replacement air that you are pulling down the stairs could also mean that the flue gases from your heating furnace and water heater might be being pulled down out of the chimney.

This could mean you are poisoning yourself and family with not only carbon monoxide but also with the other combustion gases from the burned fuel.

You really should look into making a dedicated source for your replacement air.

It could very well be that you have enough holes in the rest of the house to supply your replacement air to not be pulling fumes back in to the house but if something unrelated to your lampwork were to happen at your house and you had to file an insurance claim they could decide to deny your claim because you did not have every single one of your ducks in a row.

Heaven knows they will deny a claim for the slightest reason and you could be left owing a mortgage on a house you can not live in and you can not sell.