In September 1993, the City of Chicago passed an ordinance requiring carbon monoxide (CO) detectors, detectors in all new homes with oilor gas-fired furnaces. In a similar move, Ohio Edison now requires CO detectors in all homes with fireplaces or combustion appliances that are built under its Good Cents residential construction program; other utilitysponsored programs have promised to follow suit. These rules are probably just the beginning of a trend. Carbon monoxide is an odorless, tasteless, invisible, yet potentially deadly gas that's produced wherever there's incomplete combustion. Since combustion is never 100% efficient, any combustion appliance can pose a threat (see "Common Sources of Carbon Monoxide," below). Dangerous CO concentrations could come from a woodstove, a fireplace, a gas range — even a car
