A new state law will take effect for residential real estate transfers taking place after Jan. 1, 2014, requiring one- and two-family homes built before Oct. 1, 2005 to have both smoke and carbon monoxide detectors. Homes built after Oct. 1, 2005 are already required to have hardwired smoke and carbon monoxide detectors. Carbon monoxide is an odorless, colorless gas that can cause sudden illness and death. CO causes more than 400 deaths, 20,000 emergency room visits and 4,000 hospitalizations a year, according to the Connecticut Association of Realtors. Sellers will be asked to sign an affidavit at closing concerning smoke and carbon monoxide detectors. An affidavit is a statement under oath that must be signed in front of a notary or attorney. The law requires that the seller provide the affidavit or provide the buyer a $250 credit against the purchase price at closing. Detectors may be battery operated, unless the building code at the time the house was built required the installation of hardwired smoke (Oct. 1985) and\/or carbon monoxide (Oct. 2005) detectors. For more information go to www.ctrealtor.com\/carbonmonoxide.