A CBC investigation into unsanitary conditions at the nation's hospitals has sparked a change in policy by Canada's biggest health authority and a flood of email messages from concerned viewers.

With hidden cameras, including Canada's first hidden camera glow-gel test, the consumer show Marketplace visited several hospitals in Ontario and British Columbia, secretly applying a harmless gel to high-touch surfaces, then returning 24 hours later to see whether the gel had been removed, which would indicate the surface had been cleaned.

The program revealed many instances where cleaning had not been carried out, and that sparked a response from the Niagara Health System (NHS), the biggest in the country, whose hospitals have suffered a recent Clostridium difficile outbreak. It has decided to end its relationship with the private U.S. cleaning company Aramark.

NHS authorities wouldn’t specify why they made the move, but did tell CBC News they will be adding "the equivalent of 18 new full-time cleaning positions." It has been suggested that Aramark was at least partly to blame for the C. difficile outbreaks.

"They made decisions around staffing levels," Eoin Callan of the Service Employees International Union told CBC News. "They made decisions around what was cleaned, what was not cleaned — how frequently things were cleaned. And they also had an incentive to use cheaper diluted cleaning chemicals that were not as effective because it allowed them to pad their profit margins."

Ontario Minister of Health Deb Matthews wouldn't talk on camera, but told Marketplace: "We expect our hospitals to make the best decisions to protect patient safety in their communities."

The NHS decision may be good news for those awaiting a hospital stay, but cold comfort to people such as Ken Hough, who returned home three weeks ago after a stay at St. Thomas Elgin General Hospital in St. Thomas, Ont.

"You really wouldn't believe it, unless you've seen it," Hough told Marketplace reporter Erica Johnson, describing rooms where he says dirty bandages and plastic needle covers littered the floor.

The bathroom was the worst, he said.

"Feces on the back of the toilet," he recalled. "You'd go in to use it, and you'd pivot. I put on rubber gloves to use the toilet seat and just thought, no, I'm not doing this."

Emails from across the country echoed Hough's observations.

"The waste baskets in the bathroom were overflowing," an email from Vancouver read. It took "three days to clean up vomit," a Calgary viewer wrote. And an email from Winnipeg described "feces left on the floor" for days.

About one-third of hospitals in Ontario outsource their janitorial services, CBC News has learned, and that figure is higher in British Columbia and some other provinces.

With files from the CBC's Erica Johnson