They found out two days after Christmas when the doctor came back with Joe Linnertz's diagnosis: lung cancer.

To Linnertz and his wife Gloria, the diagnosis made no sense.

But the doctor was clear: If you don’t have a heart attack, and the chemo doesn’t kill you, the lung cancer will take your life.

Linnertz had never smoked. He was active. He had inherited heart issues from his dad, but that had nothing to do with the diagnosis Linnertz had just been given at a doctor’s office in Swansea, Illinois, half an hour outside his home in Waterloo.

Gloria and Joe Linnertz had racked their minds, but they hadn’t considered one of the most obvious possibilities — radon.

Home sellers in Illinois, like in New York, still aren’t required to test for the gas before selling. The seller of the Linnertz’s home certainly hadn’t.

Joe had suggested it when they first bought the house, but Gloria dismissed the idea, and they didn’t test.

That was in 1988.

In 2006, six weeks after his diagnosis, he was dead at 73.

Radon exposure is the second-leading cause of lung cancer deaths in the United States, and the leading cause of lung cancer deaths for non-smokers.

In New York alone, 900 to 1,000 people die of radon-induced lung cancer every year, according to the EPA. Most people, though, know little about it.

They don't know, for instance, that every year, radon-induced lung cancer kills about 21,000 Americans, according to the EPA. They don't know that patients diagnosed with radon-induced lung cancer have a less than 50 percent chance of living a year, and a less than 15 percent chance of living five years. don't know that living in a house with 1 pCi/L of radon for a year is equivalent to smoking two cigarettes a day for a year.

And that lack of awareness often means dangerously high levels of the gas go undetected — like in the southern half of upstate New York, where 10 counties have levels above the EPA's 4 pCi/L action level.

Officials in the EPA's radon programs have tried to educate people about the dangers of radon and get them to test their homes, but those attempts may not last for long — the Trump administration's proposed 31 percent cut to the EPA includes elimination of all radon programs.

A naturally occurring gas, radon itself isn't dangerous, said Jay Lubin, scientist emeritus at the National Cancer Institute whose research focused on the epidemiology of radon exposure. But its decay products — lead, polonium and bismuth — are. That's because in contrast to radon, Lubin said, they can penetrate skin. You inhale radon, it decays, and its progeny — all solid particles — penetrate the cells in the lining of your lungs and the DNA inside.

About 30 percent of New York homes whose test results have been reported to the state have radon levels above the level the EPA considers safe. Five percent of those houses show levels four times that amount.

In some counties, over half of reported levels are above what the EPA considers safe.

Those findings, from a New York Health Department database of test results since 1987, suggest few homeowners, buyers or sellers are using effective radon mitigation techniques, if any.

"It's probably a very small percentage of sellers who do (a radon test) before they get ready to sell homes," said Terrie Burke, president of the Elmira Corning Board of Realtors.

About one out of every 15 homes in the country, or nearly 7 percent, has elevated levels of radon, according to the EPA.

In New York, homes that have been tested and reported to the state show levels five times that, according to state data. In the Southern half of the state alone — excluding New York City and Westchester, Nassau, Suffolk and Rockland counties — 43 percent of those homes have elevated radon levels.

In Cortland County, 68 percent of reported homes are above levels considered safe. In Chemung, it's 55 percent; in Steuben, 54 percent; and in Tioga, 51 percent.

In the more-populated counties, the levels are lower. The record of basement readings shows 47 percent of tested homes in Onondaga County (Syracuse) are above levels considered safe. In Erie County (Buffalo), it's 22 percent; in Monroe (Rochester), 17 percent.

Though it's the standard used in most radon research, the EPA's 4 pCi/L action level is actually much higher than what's safe for humans to be around, said William Field, a professor at the University of Iowa College of Public Health and one of the country's top radon researchers.

"The 4pci/L (picocuries per liter) is not a health-based guideline," Field said.

Most action levels developed by the EPA are set at a level at which the contaminant would cause about one out of 100,000 people to develop a specific disease.

But that isn't true of the EPA's radon action level.

"If it was truly health-based, the action level would be 0.4," Field said, or one-tenth of the agency's current level.

In fact, the EPA's action level for radon in water reflects this.

"The problem with radon in water is not drinking the water. It's that it becomes airborne in the home," Field said.

If the EPA's action level were at the 0.4 pCi/L health-based guideline, not a single county in New York would have basement median measurements that fall at or beneath that level, according to the readings in Health Department database. The county with the lowest median measurement — Franklin County with 0.89 pCi/L — would still have over twice the amount considered safe.

Just three counties — Hamilton, Franklin and New York — would have first floor median measurements that fall at or below the 0.4 pCi/L threshold, based on the tests that have been recorded.

"The arbitrary number of 4 pCi/L was established by eight guys sitting in a room like this," said George Schambach, president of the New York State chapter of the American Association of Radon Scientists and Technologists and a radon inspector in the Binghamton area.

The data also show that 67 percent of radon-induced lung cancer occurs below the 4 pCi/L threshold, said Field.

The World Health Organization's action level, for instance, is 2.7 pCi/L, a level 31 New York counties surpass in their basement's median measurements.

But when U.S. regulators sat down decades ago to establish acceptable levels of radon in homes, the technology wasn't nearly as advanced as it is today. So they set levels that seemed practical, Schambach said.

Today, a combination of PVC piping and fans can easily get a home's radon level below 4 pCi/L.

The EPA classifies 34 New York counties as "Zone 1" areas, meaning they have radon levels above 4 pCi/L.

Across the country, "Zone 1" areas appear in a pattern that can best be described as a doughnut next to a belt. Western South Dakota and Nebraska are the doughnut hole, with levels beneath 4.0 pCi/L. The surrounding states all have elevated levels.

Not a single county in Iowa or North Dakota has median radon levels below 4.0 pCi/L.

To the east of the doughnut, the elevated levels extend like a belt through the middle of Illinois, Indiana, Ohio and Pennsylvania. Then it moves southward through the Appalachian range, and upward into southern New York. Elevated levels also reappear throughout Maine.

Iowa has the highest median rate of radon of any state in the U.S., and though New York's levels are less consistent, the state has extremely high levels in certain places.

The highest levels in the nation are found in the Reading Prong in Pennsylvania, part of the Appalachian Mountains. There, elevated levels of uranium lead to dangerous levels of radon.

Within southern New York, the levels vary by county, and within each county, the levels vary by municipality.

Broome, whose highest levels are found in Fenton and Conklin, with 6.41 and 6.16 pCi/L basement medians, respectively, is actually one of the counties that's better off.

The levels in other counties — like the ones below, which constitute the five counties with the highest median radon measurements in the state — are particularly alarming:

Cortland County Taylor: 10.2 pCi/L Homer: 9.93 pCi/L Cortlandville: 9.77 pCi/L Preble: 8.92 pCi/L Cortland: 8.69 pCi/L

Chemung County Big Flats: 10.76 pCi/L Southport: 8.8 pCi/L Horseheads: 7.83 pCi/L Elmira: 6.48 pCi/L Catlin: 5.96 pCi/L

Steuben County Rathbone: 15.97 pCi/L Bradford: 12.57 pCi/L Bath: 11.31 pCi/L Wayland: 11.28 pCi/L Tuscarora: 10.35 pCi/L

Chenango County Smithville: 25.7 pCi/L Lincklaen: 15.2 pCi/L Pitcher: 6.62 pCi/L Sherburne: 6.18 pCi/L Columbus: 6.08 pCi/L

Tioga County Candor: 8.7 pCi/L Barton: 8.69 pCi/L Newark Valley: 8.04 pCi/L Nichols: 6.84 pCi/L Berkshire: 5.98 pCi/L



The technology is there, so why aren't radon levels significantly lower?

The problem, Schambach said, is that people often don't get their homes tested. And even when they do, they don't always mitigate.

Buyers will receive credits to pay for mitigation if testing shows high levels, but those credits often don't translate to radon mitigation systems.

If someone gives you a $1,200 credit to install a mitigation system, why not use it to pay for a couch? Or put it toward a new car?

From buyer to buyer to buyer, that cycle can continue, Schambach said, because there are few federal or state laws regulating the gas.

Home sellers, for instance, are not required to test the levels of radon in their home, nor are they required to mitigate the levels if they're too high.

Public universities, like Binghamton University, also aren't required to test for radon.

New York requires daycare centers in certain high-risk areas to be tested, and in Livingston County, the towns of Lima and Caledonia require new homes to be built radon-resistant.

But those are the exceptions.

Rental property owners aren't required to test for radon, unless the property is classified as Section 8 housing. And owners can't be held liable for dangerously high levels that could have been reduced with mitigation techniques.

"I talked with four different attorneys in four different states, and they said I had no case," said Jackie Nixon, who lives in a condo in the suburbs of Pittsburgh.

Nixon was diagnosed with lung cancer in June 2015. She's lucky the doctors found it.

She came in with shingles, and because she was 68 and on Medicare, she qualified for, among other tests, a free chest x-ray.

She told her doctor she had no complaints — she didn't need the exam. Well, she did have one complaint.

"The only thing is that I sing, and I'm a high soprano, and the same song that I was able to sing six months ago, now there's a certain note that I'm struggling to reach," she'd said.

But Nixon thought the issue was her. She just needed to start exercising her diaphragm, and she'd be able to hit the note again.

"I had my hand on the door, and I was going to blow this off. We both were. And she said, 'Well, let's just check.'"

A month later, Nixon was in an operating room getting a tumor on her lung removed.

When Nixon returned from the hospital, she tested her condo. Radon levels were at 3 pCi/L, below the EPA's action level, but the levels in the condos beneath her, on the first floor, were much higher. On one side of the building, a neighbor's condo turned up 9 pCi/L of radon. On the other side, a condo turned up 18 pCi/L, 4.5 times the EPA's action level.

"Right now, there are more homes with high radon levels than there were 30 years ago," he said. "They build houses in high radon areas, and they don't test these houses, they don't mitigate these houses."

Even when houses are tested or systems are installed, there's no guarantee of safe radon levels.

"We know that over 60 percent of the radon systems installed don't work because they're installed incorrectly," Schambach said. Fifty percent of the testing is also done incorrectly.

New York state doesn't require radon testers or mitigators to be certified, although radon samples must be tested in state-certified labs.

The result, Schambach said, is shoddy work. He described radon tests conducted in the homes of his clients before he did ones of his own.

Testers are supposed to place two charcoal canisters four inches apart on the floor being tested. In one home, he found charcoal canisters on different floors — one in the basement, the other on the first floor. In another home, he found a canister on the first floor and a second on the second floor.

"If we don't regulate ourselves, the government is going to have to regulate us," he said.

In fact, that's exactly what he wants New York to do — mandate training and certification of radon testers and mitigators.

To that end, he's worked to get a bill to the New York State Assembly establishing licensing requirements. The bill would set up a six-person advisory council tasked with creating standards, and would require all radon testers and mitigation professionals to complete a national radon certification program.

Assemblywoman Donna Lupardo, D-District 123, is the bill's sponsor.

Another bill, sponsored by Assemblyman Daniel O'Donnell, D-District 69, would require people to test their homes for radon and disclose the results before selling them.

Schambach is skeptical O'Donnell's legislation will pass this session, but he thinks it can get through after the certification legislation passes.

For some people, though, legislation, whether state, federal or local, may come too late.

Gloria Linnertz, who lost her husband to lung cancer, has spent the past 11 years lobbying for radon testing and awareness laws.

She founded her own organization, Citizens for Radioactive Radon Reduction, and she travels across the country meeting with advocates and people who have been affected by radon-induced lung cancer.

Her advocacy has led to significant changes in her home state of Illinois.

In 2013, the Illinois legislature passed a law requiring new residential construction to be radon resistant. In 2007, the legislature passed a bill requiring all home buyers to receive information about the risks of radon.

"Because of all this," she said, "God gave me something to do the rest of my life."

Before the bill went into law in 2008, just eight percent of home buyers got their homes tested. Today, it's 55 percent.

Follow @HannahRSchwarz on Twitter.