Jared Heinrich has fought fires for the Modesto Fire Department for 11 years.

Surrounded by smoke and flames and dirty air, getting cancer is never far from his mind.

"This is an inherently dangerous job that we do and you can't protect from all smoke inhalation, especially in the wild land," said Heinrich, who works out of Modesto's Fire Station 1.

To ease the minds of the more than 100 firefighters at the department, the firefighters union contacted CancerDogs of Canada.

The cancer screening service company uses specially trained Beagles and Hounds to detect the odor of all types of cancer in a person's exhaled breath.

"When we receive masks, we transfer them to pill bottles. The pill bottles are presented to the dog and the dog will systematically sniff each sample. If they smell cancer, they'll put their paw to indicate," said CancerDogs founder Glenn Ferguson.

A dermatological test and blood test is then recommended for further confirmation.

Ferguson says it has a 95 percent accuracy rate for detecting cancer or pre-cancer.

Testing on 20,000 firefighters with 40 different departments around the country has been conducted since testing began in 2011.

In the first test conducted by the Modesto Fire Department two years ago, no samples came back positive for cancer.

Jared Heinrich has battled fires in Modesto 11 years.

Contracting cancer is not far from his mind.

“This is an inherently dangerous job that we do and you can’t protect from all smoke inhalation especially in the wild land," says Heinrich.

But there is an unconventional way to detect it: through the use of cancer sniffing dogs in Canada.

“The idea of job related cancer actually weighed pretty heavily on them. Unfortunately we’ve had quite a few guys out of here develop cancer prior to leaving or actually leaving work," says Modesto firefighter Jeremy Eldredge.

Since 2011, CancerDogs of Canada has tested 20,000 firefighters from 40 departments across the U.S.

Firefighters breathe for 10 minutes into surgical masks and then mail them to the lab in Ottawa.

Four beagles and hounds paw a diagnosis nearly instantaneously.

The accuracy rate for detection is 95 percent.

And there is a big reason for the testing with dogs.

A five-year government study ending in 2015 showed higher rates of certain types of cancer for firefighters than the general public.

The National Institute for Occupational Safety and Health (NIOSH) studied 30,000 firefighters who served in Chicago, Philadelphia and San Francisco Fire Departments between 1950 and 2010.

Among the findings, the chance of lung cancer diagnosis or death increased with the amount of time spent at fires.

This is the second time Modesto firefighters have submitted samples. The first time was two years ago.

Jason Hernandez, who has worked in the department for over a year, did it for the first time.

“It’s a sense of security for both myself and my family. One of the big things it could be or have a pre-determination of cancer. Not at this very moment, but in the future," says Hernandez.

According to CancerDogs, 20-30 percent of samples submitted will sniff positive for cancer.

So far, no one is positive in Modesto and they hope it stays that way.