Babies are dying as you read this, says Tom Rodgers. "Gassed," is how he puts it on a Web site with alarming domain names: GassingAmerica.us, DeadlyFumes.us, HUDsToxicHell.us.

The problem, he says, is that HUD-manufactured homes — the millions of low-cost factory-built homes that fall under federal regulations — typically come equipped with furnace exhaust vents on the roof that are placed too close to the powered air-intake pipe. Under certain conditions — depending on wind direction and snow accumulation on the roof — the exhaust is sucked back in, he argues, and that means that carbon monoxide wafts unseen through the house.

Rodgers, a retired scientist, and his friend Jay Bishop, a retired chemical engineer, are adamant about this. For the past year they have doggedly tried to get the attention of state and local officials, as well as the U.S. Department of Housing and Urban Development, which oversees the homes.

To Rodgers and Bishop, it's simply a matter of common sense. You would never let a child play 3 feet from a car exhaust pipe, they argue, and yet HUD code allows the furnace exhaust vent to be located as close as 3 horizontal feet from the powered air intake. Most municipal codes put that distance at no closer than 10 feet (sometimes 12 feet) horizontally, or 3 feet vertically.

Despite a year of lobbying, their main success so far is an e-mail sent from HUD's office of press relations to the Deseret News, 10 months after the two men first contacted the federal department: "HUD has the matter under review. Based on the results of that review, it may be referred to the Manufactured Housing Consensus Committee for their recommendations."

According to HUD spokesman Lemar Wooley, Rodgers' inquiry is the first the department has received about the possible carbon-monoxide danger in HUD homes, although HUD has allowed the 3-foot vent-intake design for more than 30 years.

It's hard to know what to make of the lack of complaints. Does it mean that there haven't been any problems? Or that the problems have gone undetected and misdiagnosed? Like much in this saga, it's hard to tell what is proof and what is not. It's hard to know whether proof should matter.