More than eight out of 10 homeless people surveyed by researchers at St. Michael's Hospital and elsewhere have at least one chronic health condition and more than half have a mental health problem.

People who are "vulnerably housed" - meaning they live in unsafe, unstable or unaffordable housing - had equally poor, and in some cases worse, health, the survey found.

The underlying cause for these health issues is poverty, said Dr. Stephen Hwang, the principal investigator of the study and a physician-researcher at the hospital's Centre for Research on Inner City Health.

"Poor housing conditions and poor health are closely linked," said Dr. Hwang. "We need to treat both problems."

Results of the survey were published in the International Journal of Public Health.

The survey is part of the first examination of the longitudinal changes in the health and housing status of Canadians. The Research Alliance for Canadian Homelessness, Housing, and Health, is tracking 1,200 homeless and vulnerably housed single adults in Vancouver, Toronto and Ottawa over three years. The alliance, known as REACH3, is headed by Dr. Hwang and includes some of Canada's leading academic researchers and community organizations with expertise on homelessness.

On any given night, about 5,000 people in Toronto, 900 people in Ottawa and 2,700 people in Vancouver are homeless. Over the course of a year, an estimated 150,000 to 300,000 Canadians will experience homelessness. A report by REACH3 released in November found that for every one person who is homeless, another 23 live in unsafe, crowded or unaffordable housing.

Participants in the survey reported having at least one chronic health condition, such as diabetes and heart disease, and more than 50 per cent reported being diagnosed with a mental health problem.

The study did not include comparable figures for the general population, but previous research has found that homeless people have much poorer health than other members of society.

The 2007 Street Health Report, a survey of the health status and needs of homeless people in downtown Toronto, found that while 61 per cent of the general population reported they were in excellent or very good health, only 29 per cent of homeless people felt they were. While 40 per cent of homeless people said they were in fair or poor health, only 9 per cent of the general population responded that way.