More Minnesotans are fixing up their homes to reduce the level of cancer-causing radon gas, partly because of a year-old state law governing real estate sales.

The Minnesota Radon Awareness Act, which took effect last January, requires home sellers to notify buyers if the home has been tested for radon, provide the results of that test and disclose if any work has been done to fix problems. Sellers are also required to provide a “warning statement” and written information about radon to buyers.

The number of homes getting radon mitigation work has averaged 1,279 annually in recent years, according to the Minnesota Department of Health. But in the first nine months of 2014, that number had already nearly doubled, to 2,389.

The trend has been driven in part by buyers who are more aware of the health risks of radon, said Dan Tranter, the department’s indoor air unit supervisor. Radon, a colorless and odorless gas, is the top environmental cause of cancer deaths in the U.S., according to the Health Department. It’s also the most common cause of lung cancer among nonsmokers, killing more than 21,000 people each year nationwide.

Officials estimate that 40 percent of Minnesota homes have dangerous radon levels.

“We encourage every homeowner to test their home and fix it,” Tranter said. “Because if they don’t now, they may have to during the home sale — and they can also receive the benefits of reduced radon exposures.”

Radon testing takes a few days, and homeowners can get test kits from city and county health departments, hardware stores or radon testing labs. Mitigation work typically involves installing a pipe beneath the home that helps vent dangerous gases out of the home.

Tranter recommends that home buyers and sellers enlist the help of certified radon reduction professionals. His agency maintains a directory of contractors on its website.