Healthy Home Basics - Garages

A garage often contains a number of toxic chemicals in the form of paints, solvents, fertilizers, insect repellents, etc. But the largest polluter is generally the family car. A hot automobile inside an attached garage can give off a variety of offensive odors that easily seep into the living space. Houses with attached garages typically have gasoline concentrations that are 10 times outdoor levels, but the indoor concentration of gasoline can sometimes be as much as 50 times higher than the outdoor level. One study found that benzene concentrations from gasoline-fueled vehicles can reach hundreds of parts per billion in attached garages, and the benzene can migrate into the living space exposing the occupants. 

If we still rode horses every day, we’d never have a barn attached to the house because the animal odors would be objectionable. Yet houses routinely have an attached garage which contains much more unhealthy odors. Detached garages are often preferred to keep exhaust gases, and other pollutants, from seeping into the living space of a loosely constructed house.

An attached garage should have an exhaust fan installed to minimize any contamination of the air in the house. The fan can be controlled by a timer so, when a hot automobile is pulled in, the fan can be turned on and allowed to run for an hour or so until the exhaust gases have dissipated. Sometimes it is recommended that a 100-cfm exhaust fan be running continuously in an attached garage. As an alternative, you can run a pair of 6" diameter ducts from the garage ceiling up through the roof to a pair of turbine roof ventilators, such as the Whirlybird ventilators made by Lomanco, Inc. This is a form of passive ventilation and it will continuously ventilate the garage without the electricity. Of course, this can’t be done if there is a room over the garage—unless you want a pair of ducts running up through that room. In either case, make sure the exhaust fan or the passive ducts don’t cause a chimney in the garage to backdraft.

If you insist on an attached garage, make sure it is sealed as tightly as possible to prevent garage air from entering the house. Make sure the service door into the house is weather-stripped, and consider an automatic closer. And, don’t locate a forced-air furnace/air conditioner in an attached garage.

Another danger with garage...