Research in Vancouver, Toronto and Ottawa suggests that for every person sleeping on the street, there are 23 more who are at risk of becoming homeless because they are living in unaffordable, crowded and unsafe conditions.

And many of these people, even though they have roofs over their heads, are living with the very same chronic health problems, hunger and mental illness as the homeless.

The research comes from The Research Alliance for Canadian Homelessness, Housing and Health, headed up by Dr. Stephen Hwang of St. Michael's Hospital in Toronto.

He says that his team's research suggests that Canada's housing crisis is even worse than previously thought, calling it a "hidden emergency" that is being ignored.

"Before now, researchers and decision-makers have often thought of these groups, the homeless and the vulnerably housed, as two distinct populations, with two different levels of need," Hwang said in a news release. "This study paints a different picture."

The report by Hwang's group notes there are 17,000 shelter beds regularly available across the country. But there are also about 400,000 across Canada who are vulnerably housed and at risk of becoming homeless.

The study tracked 1,200 homeless and "precariously housed" people in the three cities over a two-year period.

They found that half of them had a history of mental illness, and almost two-thirds had a traumatic brain injury at some point.

Many of them are dealing with harsh physical-health issues too, such as arthritis, hepatitis B, asthma and high blood pressure. A third of them say they're having trouble finding enough to eat.

More than half these people visited an emergency department in the past year and 38 per cent cannot get the health care they need.

The researchers estimate that the life spans of the people studied are about seven to 10 years shorter than the general Canadian population.

Researchers plan to track them in the coming years to see how their housing and health status have changed. In the next phase of their study, the researchers will try to uncover how often homeless people get housing and stay housed, and how often the vulnerably housed become homeless. They will also investigate if whether the homeless see their health improve and health care use decrease when they find housing.

The researchers estimate that men in vulnerable housing situations are more than twice as likely as the average Canadian to commit suicide. Women in similar situations are six times more likely to commit suicide than the average Canadian.

The researchers conclude that the biggest gulf in health outcomes is not between the homeless and the housed. Rather, it's between those who have adequate housing and those who don't.

The solution, the research network argues, is for Ottawa to set standards for access to adequate housing.

"The key point is that Canada needs a national housing strategy," Hwang said.

"We all recognize that health care is important for good health, and so we have universal health care. Decent and affordable housing is just as essential for good health."

The study was funded by the Canadian Institutes of Health Research.