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Issue May 2023

Whether
the weather be fine ...

How rain and shine influence air quality
 

Bad air quickly gets to most people.
It puts a strain on well-being, performance and not least health.
Air pollution is also dependent on the weather.

Sometimes you can cut the air with a knife and dread yet another muggy day.
Sometimes there is just something in the air.

We are aware that the quality of the air around us is constantly changing — and that this often has something to do with the weather.
But how do sunshine, rain, and air masses specifically affect air quality? And how is climate change altering them?

The elements influence air quality

Not all air is the same.

Sea air has a different composition than the air in the desert or a big city. After location, the weather is the second major factor to determine the concentration of pollen, fine dust, and certain gases in the air. Fluctuations in air quality — especially those in the short-term — are mainly due to the weather. But how exactly do different weather conditions affect air quality?

Let’s take a closer look:

Sun rises, air quality drops

Sunny weather influences both the quality and the composition of the air. Intense UV radiation triggers a reaction in which nitrogen oxides interact with volatile organic compounds (VOCs) — both gaseous substances — to form ozone. During periods of good weather, ozone levels can rise sharply, which can cause people to experience headaches and dizziness.

Heat waves and long dry spells are usually accompanied by reduced air quality. Dust concentrations increase due to more intense erosion of fields and fallow land. When plants do not have enough water, they produce more pollen, which also accumulates in the air. Without rainfall, particles also remain in the air for longer.

More moisture, less pollutants

Rain and high humidity improve air quality. They ensure that fine dust, pollen, and water-soluble contaminants are washed out of the air.

Humid air also lowers ozone levels because it prevents VOCs from reacting with the nitrogen oxides present in the air.

Inversion leads to pollution

The higher you are, the colder it is. The air temperature drops by an average of 6.5 Kelvin (K) for every kilometer (10.5 K for every mile) increase in altitude. When the sun heats up the warm surface of the earth and the air directly above it, the air density decreases, causing it to rise. This is known as convection. It provides a constant exchange of air by movement in the form of wind. A warm layer of air over cold air, however, creates stable stratification, which prevents air movement and causes emissions, dust, and harmful substances to accumulate. This results in a continuous decrease in air quality and the formation of dangerous smog.

Gone by the wind

Winds move air on a large scale — and with it whatever the air is carrying. A good example of this is when cars in Europe are covered in a fine layer of Saharan dust. Before this dust settles, however, it worsens the air quality, restricts visibility, and enters our lungs.

In Asia, spring winds whip up large quantities of dust from the Gobi Desert, pick up fine dust and contaminant gases over industrial regions, and transport them as far as South Korea and Japan, where they reduce air quality.

The time of the season

Temperature also has an important effect and in most regions, it is closely linked to the seasons.

In winter, low temperatures prompt people to turn up the heating at home and make greater use of private vehicles. This increases the emission of soot particles and contaminants, which pollute the air.

From spring onwards, this pollution decreases slightly, but the pollen count increases. In summer, warm weather causes more ozone to form.

During periods of good weather, ozone accumulates in the air. On such days, people’s well-being declines and health problems increase.

How climate change is affecting air quality

Climate change is causing a long-term increase in the average temperature on Earth.

It is also causing extreme events to occur more frequently and with greater intensity. This has an impact on air quality as well. The higher temperatures extend the time in which pollen is airborne. Drought stress caused by long periods without rain also leads to increased pollen production in plants.

More stable air masses are another consequence of climate change. In summer, large areas of high pressure increasingly lead to long dry phases with little movement of air. The concentration of contaminants and dust in the air increases during these phases. All this means that air pollution is an increasing problem.

More frequent heat waves and dry periods also cause more forest fires, which release large amounts of soot, fine dust, and contaminant gases into the atmosphere, further decreasing air quality.

What’s the forecast?

There are many factors that will determine how air quality will change in the future.

The most important is the development of man-made emissions of soot, fine dust, and contaminant gases. The fewer man-made emissions in the air, the better the air quality in general and the lower the impact of the weather on it. Whatever the weather, various filtration solutions for vehicle cabins and private homes help maintain clean air and ensure driving comfort.

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