The interactions between climate change and air quality are complex, but very important. Air pollution, often resulting from human activity, plays a major role in causing the climate to warm. Pollution can also have very serious impacts on the health of humans and natural ecosystems. Air pollution damages the respiratory system in a similar manner to cigarette smoke, and studies have linked poor air quality with increased mortality, particularly in relation to heart disease and cancer rates.
When atmospheric air contains harmful amounts of gases, dust, fumes, or odours, the air is considered to be polluted. These substances are known as pollutants, and can cause significant health and environmental damage. Some examples of major pollutants include carbon dioxide, ozone, sulfur dioxide, and particulate matter. Some of those substances should be recognizable as greenhouse gases, as anthropogenic GHGs are considered pollutants due to their harmful effect on natural systems like the ocean.
Different types of air pollutants can have a variety of effects on the atmosphere, the environment, and human health. You can find a more complete list of air pollutants here.
Sources of Air Pollution
As you can see from the previous section, most types of air pollution result from anthropogenic activity, like the combustion of fossil fuels. Coal-fired power plants and gasoline-powered cars are both strong examples of fossil fuel combustion. Industrial activities are also a major source of air pollution. Mass production and waste incineration both produce carbon monoxide (CO), greenhouse gases, and chemicals that are then released high into the atmosphere by large smoke-stacks.
Agriculture is another example of a human activity that pollutes the atmosphere. When forests are cleared to make room for farms, the trees are processed to produce paper or construction materials, and the carbon sequestered within them is released into the atmosphere. In and of itself, farming is a highly polluting practice because fertilizer and pesticide use both contribute to air pollution. Methane is produced by livestock farming because bacteria located in the animals’ guts produce the gas as a by-product of digestion. Finally, most farm equipment depends on gasoline or diesel for energy. These fossil fuels produce many different pollutants, including CO2, CO, NO2, and primary particulate matter.
Air pollution does occur naturally, though not nearly as consistently as anthropogenic air pollution. Some examples of natural air pollution include soil eroded by wind, pollen dispersal, volcanic eruptions, and forest fires. Volcanic eruptions are massive pollution events that emit huge amounts of sulphur dioxide into the atmosphere. The sulphur can block out the sun for extended periods of time, and even has the potential to alter the local climate.
Forest fires are another major source of natural air pollution. The incineration of billions of trees releases huge amounts of carbon dioxide and particulate matter of all sizes into the atmosphere. What is so concerning for British Columbia about pollution from forest fires, is that fire events are expected to get much worse in the coming decades as the climate warms. This creates a positive feedback loop where the climate gets warmer and drier, reducing the amount of water available to the forests and causing them to dry out. Because dry wood is much more combustible than wet wood, these drought conditions cause the wildfires to be much worse than they would otherwise be. If the size and intensity of the fires are much worse, more trees are burned and more greenhouse gases are released into the atmosphere. These gases enhance the effects of climate change, causing the region to be even warmer and drier during the next fire season. This is just one effect of a positive feedback cycle caused by climate change that exacerbates the effects of climate change and creates the conditions necessary for future change.
Indoor Air Quality
To this point, air pollution has largely been discussed with regards to an atmospheric/outdoors context, but indoor air pollution is also an important health concern, and there are those who expect it to become a greater problem in the face of future climate change. Canadians spend about 90% of their time indoors, so you can imagine the effects that poor air quality in those environments might have on the health of an individual. Remember that cigarettes, household cleaners and chemicals, scented products, and the presence of mould or mildew can all impact indoor air quality. This is especially important in households with children, who are more sensitive to air pollutants.
There are a couple reasons why indoor air quality is linked to climate change. First, as the summers get hotter and drier, people are likely to spend more time indoors, where they are protected from the sun and heat by a roof and air conditioning. If those indoor environments contain harmful concentrations of indoor air pollution, than this behaviour change will increase the individual’s exposure to that pollution, potentially increasing the risk of health impacts.
The construction of the building in question plays a significant role in indoor air quality. Beyond the building materials, cleaners, and chemicals used during construction, the building envelop plays an important role in determining the rate at which air is exchanged between the interior and the exterior of the building. It is a commonly used climate change mitigation strategy to construct buildings with tight envelops, as this reduces airflow and energy loss from the building. In buildings such as these, a harmful pollutant will persist for an extended period of time because there is minimal air exchange. This highlights the importance of building well ventilated buildings, which may or may not include a mechanical ventilation system.
Finally, climate change can influence indoor air quality because more atmospheric CO2 and heavier rainstorms could increase the growth of mould inside houses and buildings. Mould growth releases airborne spores and has a strong influence on indoor air quality, particularly for people with allergies. Houses with tight building envelopes are at an even greater risk of mould growth because they can trap moisture inside along with air and energy. This moisture can help stimulate the growth of mould in hidden places where it can impact air quality. The best way to prevent problems like this is to carefully monitor moisture and humidity levels in the building both during and after construction. Mould will grow anywhere there is organic matter, water, and heat, so making sure that everything is completely dry before sealing off any areas like the interior of a wall. Taking steps to prevent mould growth and ensuring that the building is properly ventilated are two of the most important strategies for reducing health risks from indoor air pollution.