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For the health of the city
How does wealth affect how well and how long people in North American cities live? Can the services a city offers its residents prolong their lives?
Finding the answers to these and other questions preoccupies Geography Professor Nancy Ross, who's on the cutting edge of health research in Canada.
For Ross, a health and urban geographer, health isn't just about a person's individual characteristics but how a person interacts with the physical and social environment they're exposed to over a lifetime of living and working. "What determines our health is a combination of who we are and the experiences of our daily lives," she says.
Although an undergraduate medical geography course twigged her interest, her family background also played a role. "I grew up in New Glasgow, Nova Scotia," says Ross. "My parents are from Cape Breton. Being from a place that seems to be disadvantaged and seeing the health effects on people has informed my work."
Ross came to McGill in fall 2001, just months after receiving a New Investigator Award from the federal government's Canadian Institutes of Health Research. The five-year fellowship "really allows me to get my research career off the ground," says Ross.
Along with James Dunn of the University of Calgary, Ross is leading a four-year research program titled Metropolitan Socio-economic Inequality and Population Health. Ross is thrilled by the prospect of their research influencing social policy.
Her work studies community connection and health, the tie-in between where people live, their socio-economic status, chances for a disability-free life, and child health and development.
In 1998 American public health researchers George A. Kaplan and John W. Lynch published a groundbreaking study that looked at how income inequality—the gap between the rich and the poor—affected life expectancy of people living in 282 U.S. cities. The findings were startling: areas with high rates of income inequality and low average incomes had 139.8 deaths per 100,000 more than areas with low income inequality and high average incomes. That difference, the study noted, can be compared to the combined loss of life from lung cancer, diabetes, motor vehicle crashes, human immunodeficiency virus (HIV) infection, suicide and homicide in 1995.
Ross was working at Statistics Canada at the time. They knew Canadians tend to live longer than Americans but they didn't know how the gap between the rich and the poor affected mortality and health.
Using vital statistics and census data from 1990 and 1991 for cities with populations of over 50,000, the researchers looked at 282 U.S. cities in 50 states and 53 Canadian cities in 10 provinces. They examined death rates, age-adjusted to Canada's population in 1991, and measured income inequality by looking at the proportion of total household income in the community that belongs to the bottom 50 percent of households. The closer the score to .50 on the median share measure, the more equal the income is distributed.
For cities in the U.S. the proportion of income distributed ranged from .15 (least equal) in Bryan Texas to .25 (most equal) in Jacksonville, North Carolina for the United States. Canadian cities ranged from .22 for Montreal to .26 for Barrie, Ontario. When they compared these to mortality rates, they were surprised to find no significant relationship between income inequality and mortality.
"The prognosis was 'we're going to find something,'" says Ross. "But when we did the work we didn't find anything"
Published in the April 2000 issue of the British Medical Journal the findings drew plenty of media attention and were cited by then Canadian Health Minister Allan Rock. Ross is thrilled by the prospect of influencing social policy with her research.
In another study, Ross and Dunn compared income segregation—the tendency of people to separate into homogenous neighbourhoods in terms of their income—with income inequality and death rates of working-age people (25 to 64).
The study's results showed there's a strong connection between increased residential segregation and lower life expectancy in the U.S. but found no such connection in Canada.
Research in Australia suggests Canada isn't the statistical anomaly, it's the U.S. "What it's starting to look like is the U.S. and developing countries [appear to be] the principal areas where you can find a relationship between the gap between the rich and the poor and poor health," Ross says.
Why such differences between Canada and the U.S.? Hypotheses so far include health care, different historical trends in income inequality and perhaps "something more subtle" about the tendency of Canadian cities to be more "public" in nature, Ross says.
"Anything that impedes the individual's socio-economic position is likely to impede their health chances in life," Ross says, adding that existing evidence shows stress and hassle in a person's life hurts their health.
In Canada social resources are distributed more equally, Ross says. Taxation and transfer policies might be buffering both individual and regional income gaps.
"In some cities in the United States, the poverty becomes very concentrated," Ross says. A good education tends to lead to a decent job but what if no one in your environment has a good education—or a job? "The larger and more continuous the poverty gets, the more people are cut off from job networks," she says.
Compared to Canadian municipalities, U.S. cities are extremely fragmented, Ross says. Poor cities fight for resources to provide badly needed services while rich suburban cities fight to zone out the poor.
"The variation in school quality tends to be a lot greater in the United States than it does in Canada," Ross says. "Canada does have a gap between the rich and the poor in grade three achievement but it doesn't come close to that of the United States, so we think of the provision of public goods as effectively evening out health and life chances in Canadian studies."
"In less than 20 years, the life expectancy gap has more than doubled between Canada and the United States," Ross says. "In 1976 the life expectancy gap was about one year in favour of Canada, in 1996 it was two-and-a-half years. That's a lot of life. So you can see the motivation of doing these kinds of cross-national experiments."