Quebec studies finds positive and negative effects of living in cities

A shopper walks in downtown Montreal, Tuesday, Dec. 19, 2023. (Christinne Muschi, The Canadian Press)

Quebec is increasingly seeking to make its cities denser in order to promote sustainable mobility and better protect agricultural areas, among other things. Densification has certain negative effects on health, but there are also benefits, according to a recent report by the INSPQ.

The Quebec Institute of Public Health (INSPQ) analyzed a number of studies in order to draw up a portrait of the impacts of densification on health. It looked at levels of physical activity and walking, noise and air quality, the risk of injury from vehicles, and social interactions.

Poor air quality can result in higher mortality or hospitalization rates, the analysis points out, adding that air pollution can affect even people in good health, but those suffering from asthma or other respiratory disorders, as well as the elderly and young children, are at greater risk.

"We know that when we breathe in air pollution, there will be health effects such as an increased risk of certain cancers, an increased frequency of heart attacks, and an increase in the number of people who have to be admitted to hospital with respiratory problems", said Patrick Hayes, professor of Analytical and Atmospheric Chemistry at the Université de Montréal.

He said that people who live close to a source of pollution, such as a busy road, are more likely to suffer from air quality poisoning. Hayes pointed out that air quality varies enormously from one part of a city to another.

Furthermore, large cities often have a better public transport network and a greater proportion of the population travel on foot or by bicycle.

"There is an effect that will cancel each other out a little in the sense that total emissions are reduced, but emissions per unit area will increase," said Hayes. "There are two effects that go in opposite directions, so it's a question of (whether) the reduction in emissions has an effect that is greater than the effects of densification."

Hayes stressed the importance of reducing pollution, in particular by reducing car travel.

"There are certain sources that we cannot easily control, such as the smoke from the forest fires we saw last summer in Montreal," he said. "The frequency and intensity of forest fires is influenced by climate change but it's not something we can control directly."

Hayes also said that Quebec is geographically poorly placed in terms of prevailing winds, which means that we receive some of the air pollution from the north-eastern United States and Ontario.

The INSPQ report also explored the effects of noise on health. It indicates that exposure to excessive noise can disrupt sleep, and that proximity to car traffic or an airport is associated with "high blood pressure and cardiovascular disease, reduced quality of life and well-being, and possible impairment of cognitive development in children."

More social interaction in the city

The quantity and quality of social ties between individuals have positive effects on health, the report reads.

People with more social connections live longer, while isolation is associated with a risk of depression, cognitive decline, physical inactivity and generally poorer health.

Public spaces -- which are generally more heavily used in high-density cities -- play an important role in social interaction. These spaces encourage opportunities for spontaneous encounters.

Travelling by public transport, on foot or by bicycle also leads to more spontaneous encounters.

"We also know that public places, when they're well laid out, are a great source of psychological renewal," explained Linda Pagani, a professor at the Université de Montréal's School of Psychoeducation. "These days, we tend to spend too much time indoors in solitude because of our virtual lives. We've lost touch with how important chance is in life."

Pagani maintains that social interaction promotes a sense of security, reduces anxiety and sadness, and increases the feeling of belonging.

"When it's set up for social interaction and spontaneous encounters, we tend to be very positive towards each other," she added.

However, she said, overcrowding - that is, being forced to live next to and on top of each other - can have a harmful effect.

Physical activity

Road traffic inevitably leads to collisions, whether between motorists or with pedestrians and cyclists.

According to the analysis, the link between density and road trauma is mixed: "At the level of neighbourhoods within the same city, it is generally the denser neighbourhoods that suffer more collisions because of the greater number of journeys made through them. However, when cities are compared with each other, in terms of the number of kilometres travelled by car, it is the denser cities that suffer fewer collisions," the INSPQ document states.

In terms of physical activity levels, the analysis states that "urban sprawl is associated with lower levels of physical activity due to sedentary lifestyles associated with heavy car use."

This may play a role in the development of cardiovascular disease, type 2 diabetes and certain types of cancer.

According to data from the Quebec Statistics Institute, 48 per cent of the population aged 15 and over do not achieve the recommended level of physical activity per week, which is at least 150 minutes of moderate-intensity activity for adults.

Being sufficiently active has positive effects on mental health and reduces the risks associated with being overweight, such as high blood pressure and cardiovascular accidents.

This report by The Canadian Press was first published in French on March 7, 2024.

The Canadian Press health content is funded through a partnership with the Canadian Medical Association. The Canadian Press is solely responsible for editorial choices.