In November of last year, local legislators in Montgomery County, Maryland passed legislation requiring homesellers to test for radon and make the results available before putting property on the market, The Washington Post reported. Montgomery County is the first local government in the U.S. to enact such a law.

The Greater Capital Area Association of Realtors protested the legislation, arguing that it served little purpose, as most buyers make radon testing a condition upon sale. The organization also contended that current state legislation, which mandates that sellers disclose radon problems to buyers, effectively addressed the issue.

Legislators, along with officials at the Montgomery County attorney's office, asserted that buyers needed further protections.

"We are just asking people to test," Councilman Craig Rice, the bill's sponsor, explained in an interview with American University Radio. "Just to make sure that they know what may be lurking in their homes unknown that might be a silent, deadly killer."

Radon is an invisible, tasteless and odorless radioactive gas that forms in soil and groundwater deposits, according to the Environment Protection Agency. The gas usually invades homes through cracks in their foundation and can cause lung cancer in adults and children. In fact, an estimated 21,000 people die each year as a result of radon-related lung cancer.

Radon is an especially serious problem in Montgomery County, as it's centered on an area that exhibits higher than average radon levels, Bethesda Magazine reported. Indeed, the EPA considers the municipality a Zone 1 risk, meaning local radon levels exceed 4 picocuries per liter. Most public health authorities, including the EPA and World Health Organization, consider readings above 2.7 Pci/l unsafe.

The new legislation goes into affect October 16.

Radon testing kits cost as little as $15 a piece. However, most experts advise homeowners to schedule radon testing with a local home inspection company.