What is the Environment?
The environment surrounds all of us, encompassing air quality, heat levels and the severity of weather events. Climate change is a long-term shift in weather conditions that involves both changes in average conditions and changes in variability. Its greatest cause is the burning of fossil fuels, which releases carbon dioxide into the environment, leading to a greenhouse gas effect that increases temperature.
Canada is warming faster than the rest of the world. Over the last two decades, Canada has seen a dramatic increase in the frequency of extreme weather events, such as extremes in temperature, flooding, and wildfires. Current climate modelling shows that Canadian urban centres will experience at least four times as many +30 °C days per year and longer extreme heat events by 2051–2080. Wildfire seasons will become longer and more severe.
While increased levels of carbon dioxide accelerate climate change, other air pollutants can worsen our air quality. Nitrogen oxides (NOx), sulphur dioxide (SO2), carbon monoxide (CO), fine particulate matter (PM2.5) and ground level ozone (O3) are the most common air pollutants in cities. Vehicles are the largest source of nitrogen oxides but these air pollutants are also emitted from residential furnaces, industrial processes, and electricity-generating stations that are run on coal and natural gas.
Contaminants in outdoor air come from many additional sources, including other transportation sources (e.g., planes, marine traffic), industrial emissions, wildfires, wood smoke from fireplaces, and dust from construction and agriculture.
How does the environment affect health?
The World Health Organization has identified climate change as one of the greatest health threats of the 21st century. Some features that are unique to cities, such as fewer trees and plants, building materials that store heat, and buildings and vehicles that create heat through energy use, can exacerbate and amplify some effects of climate change. As a result, cities are at the front lines of adapting to climate change. For example, sea-level rise, extreme heat, reduced rainfall, and increased frequency of extreme weather events are expected to be felt more by urban populations. All of these effects have important impacts on health.
Extremely hot days can aggravate existing respiratory and cardiovascular diseases and cause heat stroke and death, while also exacerbating mental health conditions and lead to increased hospital admissions for schizophrenia, depression, dementia, Parkinson’s and Alzheimer’s disease. In addition to causing heat-related illnesses such as swelling, fainting, heat rash and heat stroke, extreme heat can also exacerbate pre-existing health conditions, especially heart disease, kidney disease and lung diseases such as asthma and COPD. Illustrating how severe the impact of extreme heat can be, in an August 2003 heat wave in France, 15,000 more people died than would have been expected given mortality rates.
The frequency and intensity of floods, wildfires, hurricanes, ice storms and heat waves have increased significantly over the last few decades, already leading to negative health outcomes. Extreme weather events have forced hundreds of thousands of Canadians to evacuate their homes, left hundreds of thousands without power for extended periods, and harmed the physical and mental health of many of those involved. Wildfires have exposed millions of people in Canada to extremely high levels of toxic air pollution.
Air pollution itself also presents a significant risk to the health and well-being of people across Canada. Health Canada estimates that it causes more than 15,300 early deaths, 2.7 million asthma symptom days and 35 million acute respiratory symptom days per year, costing the health care system $120 billion annually. As well, health issues directly related to air pollution in Canada result in 620,000 doctor visits, 92,000 emergency department visits, and 11,000 hospital admissions. At a global level, ambient PM2.5 air pollution is the fifth most common cause of death, resulting in 4.2 million deaths per year and representing 7% of deaths worldwide.
Short-term exposure to PM2.5, sulphur dioxide and nitrogen dioxide has been associated with the exacerbation of asthma, pneumonia, and bronchiolitis, resulting in more emergency department visits and hospitalizations. Long-term exposure to air pollutants has been clearly linked to premature deaths from cardiovascular disease, strokes, lung cancer and chronic obstructive pulmonary disease (COPD), as well as respiratory problems, impaired lung function, slower lung function growth in children and adolescents, cardiovascular problems, and some cancers. It has also been associated with many other negative health impacts including bladder cancer, childhood leukemia, reduced cognitive function, dementia, and adverse pregnancy outcomes.
Reducing emissions can help improve air quality and lessen the health burden of air pollution, as well as slow and mitigate the effects of climate change, including the effects on physical and mental health.
Who is affected?
Climate change presents health risks for all people living in Canada but some populations are more vulnerable to its impacts than others.
Some areas in urban centres can experience higher temperatures for longer periods because they lack trees and vegetation to cool them and are built with heat absorbing materials. The layout and design of our communities can affect the health risks presented by climate change. Homes may be built in areas that are flooded by rivers and lakes during the spring snowmelt, following extreme rainfall or by storm surges from the ocean during hurricanes.
Most of the impacts of climate change will amplify existing health hazards found in populations. How susceptible a population is to the effects of climate change will depend on their existing vulnerabilities. For example, young children, older people, and people with pre-existing health conditions such as respiratory or heart conditions, are physiologically more sensitive to the harmful impacts of wildfire smoke and heat waves.
Still others are at greater risk from climate impacts because they lack the resources to protect themselves or to recover from them. For example, people with lower incomes in cities may be harder hit by heat waves because they also tend to live in neighbourhoods that lack green space, have no access to pools, and be in homes that are not air conditioned. People without access to adequate housing, air-conditioning or who can’t get drinking water whenever they need it will have greater challenges in getting relief from extreme heat. Social isolation and mobility issues can also pose barriers to people who need to get to places with air conditioning. If someone has difficulty understanding public health warnings around heat they may be at increased risk of negative health effects of extreme heat.
In large cities, exposure to air pollution tends to be greater among lower socioeconomic status neighbourhoods. This is because they often live closer to emitting sources. For example, children of lower socioeconomic status are more likely to live in homes that are closer to vehicle traffic, industrial facilities, and also have higher exposures to PM2.5 and nitrogen dioxide.
While Canada has made impressive progress in improving air quality, even when Canadian air quality standards are met, people are still being exposed to air pollutants at levels that negatively affect health. And it’s the most vulnerable populations that bear the brunt of the burden of air pollution. Those with existing chronic conditions, such as asthma, heart, and cardiovascular issues, as well as older adults and young children, and people who spend a lot of time in or close to traffic, such as taxi drivers, police officers, people with long commutes, still face negative health consequences because of poor air quality.