Wrapped in hard plastic packaging among a row of smoke detectors, the carbon monoxide detectors blend right in. These soon-to-be-mandatory devices are waiting for consumers to give them a new home.

The July 1 deadline for owners of single-family homes to install carbon monoxide detectors in their houses is fast approaching.

A California law, passed in May 2010, requires single-family homes with an attached garage or appliances that burn fuels like gas, coal or wood to have the devices. Multifamily dwellings, such as apartment buildings or condominiums, have until Jan. 1, 2013, to comply with the law.

Failure to install carbon monoxide detectors could result in a $200 fine, although residents would get 30 days to install the devices before having to pay.

When appliances such as water heaters or gas stoves burn their fuel, one of the byproducts of combustion is carbon monoxide gas. It’s colorless and odorless and is toxic to humans and animals in high concentrations. The molecule binds to an area on red blood cells that normally carries oxygen, essentially suffocating the body’s organs.

San Jose resident Maribelle Wong said she plans to buy a carbon monoxide detector soon, but she doesn’t think many people are aware of the upcoming deadline.

There is a sign posted on the hardware counter at the local Lowe’s, but “if you don’t come here, how would you know?” she asked.

Ed Oliveira, assistant manager of the Lowe’s off Brokaw Road in San Jose, said large property management firms are more aware of their upcoming deadline. “They’re trying to get ahead of the curve,” he said. “They’re coming in and buying hundreds of them.”

The law, written by state Sen. Alan Lowenthal, D-Long Beach, aims to prevent the 30 to 40 accidental annual deaths in California due to carbon monoxide poisoning.

“It’s likely these (deaths) were exposures to leaky or faulty equipment in homes and on boats,” said Dimitri Stanich, a public information officer with the California Air Resources Board.

A check of several popular retail websites showed a range of prices for the devices, from less than $20 to more than $100. They should be installed outside each sleeping area and on every level of the home, according to the Fire Marshal’s Office.

A Centers for Disease Control and Prevention website on carbon monoxide lists symptoms of exposure, including nausea, headaches, chest pain and confusion. It says more than 400 Americans die of unintentional carbon monoxide poisoning each year, while about 4,000 are hospitalized.

Contact Jane J. Lee at 408-920-5064.