This letter from air quality scientist Jim H. White was posted to an online indoor air quality discussion group.
Subject: Re: Vent-Free Gas Heaters

I ... continue to be dismayed at the actions of both the gas industry and the regulators in the states who allow use of these appliances. Researchers at CMHC have studied spillage of combustion gases from vented appliances for years. We consider that spillage is unacceptable, as others are coming to believe, so the move to unvented combustion appliances fills us with much sorrow.

By using an unvented combustion appliance indoors we are, in effect, turning our houses into chimneys and are living in a chimney, not a house. As cavemen we left caves to get out of the smoke (and away from the mold) but here we are returning to an environment where (less dangerous, perhaps) combustion products are a normal part of the indoor environment and mold will become more common. This makes no sense, just as the use of unvented gas ranges and kerosene heaters make no sense. Surely we have not devolved to such a point that we accept living in a chimney as an acceptable way of life.

Three points:

1. Every state should use the wording "If you chose to use this product your house will become a chimney and you will be living in a chimney, in air filled with combustion gases."

2. The amount of moisture generated by burning gas indoors could be sufficient to cause serious moisture problems in some houses, with a high attendant health risk. It is highly likely that more people will be made sick by mold and dust mites, plus increased insect infestations due to dampness, than by carbon monoxide. The carbon monoxide problem is a serious one, but the moisture ones will likely be worse.

3. All states allowing use of this product should institute special laws and taxes that are used to make the seller & manufacturer specifically liable for moisture damage and increased health care costs that could be in any way attributable to the use of the product. Part of the funds should be used to initiate studies of the health of users, and part to fund groups choosing to sue the sellers/manufacturers for damages.

Surely if use of the product is allowed, the responsibility for problems due to its use should be specifically charged to those responsible for causing the problem, and that is not the user, who cannot understand all of the ramifications on its use.

Jim H. White
CMHC National Office

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