Since poor air can have a major impact on public health, it’s important to understand how pollution levels can be affected by the changing seasons. Generally speaking, winter and summer affect air quality differently, but neither is definitively worse than the other.
How Warmer Weather Affects Pollution Levels
We often think we’re getting more ‘fresh air’ in warmer weather as we tend to be outside more. However, warm weather can actually increase pollution levels. Increased solar radiation during the summer months produces more photochemical oxidants, especially ozone. A colorless reactive gas with potent oxidizing properties, ozone blocks harmful radiation from the sun when it’s in the stratosphere. However, when ozone is at ground level — in the troposphere — it becomes dangerous.
During the summer, radiation from the sun is stronger which causes ozone levels to spike at the ground level. This can lead to dangerous air conditions in the lower part of the atmosphere, where people are walking around. Ground ozone can cause painful breathing, coughing, increased asthma symptoms, and more. As a result, in some countries like the United Kingdom, air quality-related hospital admissions can climb during the summer months.
In addition to these health concerns, high ozone levels increase the rate at which other pollutants emerge. Because ozone is a reactive gas, it can sit in stagnant summer air for long periods of time and mix with other pollutants in the atmosphere, including vehicle and power plant emissions. This process can be particularly bad in areas with high vehicle traffic, like in large cities, where the amount of nitrogen oxides emitted into the atmosphere are more significant.
In addition, the increase in travel during the summer can increase pollution levels dramatically. This explains why national parks in the United States — which receive most of their traffic during the summer months — are home to some of the worst air quality in North America.
On the brighter side, warm air sits below cool air in the summer, which means toxic particles in the air are able to rise with less resistance than in the winter. As a result, pollutants are carried out of the atmosphere more easily, offering people on the ground a breath of fresh air.
The State of Play in Summer 2019
1. Wildfires Wreaking Havoc
Wildfires have been ravaging the west coast of the United States in recent years, particularly during the summer. Lately, however, policymakers and scientific forecasters have grown concerned about the relationship between wildfires and air quality — even when fires are occuring miles away from major cities. Last summer, Washington’s wildfire impacted Seattle’s air quality so intensely that breathing the city’s air equated to smoking seven cigarettes per day.
Wildfires along America’s west coast are more common and longer-lasting than ever before, creating an influx of fine particulate matter in a region known for its good air quality. To combat this trend, Olympia has increased Washington’s Department of Natural Resources funding by $50 million, money that will be used to clean up debris and reduce the volume of particulate matter in the air.
2. More Cyclones & More Smog?
As a result of climate change, we’re seeing more mixing of warm and cool air in the upper atmosphere, which has resulted in higher volumes of extratropical cyclones —often the powerful force behind blizzards and thunderstorms.
Although major storms can be deadly, they’re not always all bad: when a storm barrels through a large region, it limits the formation of certain pollutants and drives smog out of cities. However, tropical storms may no longer be as beneficial in 2019. New reports show that the air in the Arctic is warming twice as quickly as the global average, which is causing northern air to warm faster than southern air. This is a problem, as it means extratropical storms will occur more often, but the circulation of these storms will weaken, eliminating their air purifying benefits.
Additionally, the reduced circulation of extratropical cyclones may be contributing to warming, which can increase ozone levels and create even more smog. This explains why places like New Delhi are experiencing record-breaking pollution this summer.
3. No More Ice Cream in London?
Increased summer travel can significantly increase levels of vehicle exhaust, but in London, it’s not only increased traffic on the road that contribute to pollution levels — ice cream trucks standing perfectly still are also contributing to the problem. Most ice cream trucks in London run exclusively on diesel, and their engines need to stay running to keep their products frozen even when the trucks are parked.
In response to recent public protests, the city is in talks to ban ice cream trucks, especially if vendors don’t take steps to become more environmentally conscious. This is the latest step in London’s initiative to keep vehicle pollution to a minimum via the Ultra Low Emission Zone legislation.
Staying Healthy During the Summer
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