Increased Air Pollution: Is It Worse During the Summer or Winter?

Key Points

• Air pollution changes depending on the season. In summer, the main issues are photochemical smog and ground-level ozone, whereas winter brings heavier particulate matter and pollution from building heating and transport.
• Factors like humidity, pressure, wind and the temperature inversion phenomenon also influence whether the air quality is worse during a specific period.
• Understanding the differences between seasons helps better plan anti-smog activities and protect residents’ health.

For some time now, we have believed that air pollution is generally worse during cold winter weather. But is it really so? After all, humidity, air pressure, and temperature are atmospheric conditions that affect air quality and create weather.
So, is air pollution worse during the summer or winter months? The answers to these and other questions are waiting for you in today’s entry!

Table of Contents

• Air pollution in summer
• Air pollution in winter
• Winter air quality – why pollution levels rise when it’s cold?
• Air pollution: summer vs winter
• Understanding the accumulation effect between summer and winter
• The Takeaway

Air pollution in summer

If you are wondering if increased air pollution is worse during the summer or winter months, we have a surprise for you. 

It turns out that air pollution frequently is better on hot days. Nevertheless, summer haze can really irritate your eyes, throat, and lungs. As a result, you may struggle with persistent coughs or the feeling of a tight chest. Air pollution in summer may be particularly problematic for those who have asthma or hay fever.

This is because they’re exposed to all the compounds and dust mixed with ground-level ozone. It can be really dangerous for health and it may cause various conditions like circulatory problems, nausea, problems with concentration, or even heart attacks and strokes.

High levels of sunlight during summer months intensify some reactions responsible for the formation of ground-level ozone. This phenomenon is known as “photochemical smog” and is particularly prevalent in densely populated cities. Moreover, heatwaves and calm air without winds can trap pollutants close to the ground for extended periods. This makes sensitive individuals even more exposed to breathing problems.

Seasonal agricultural activities release ammonia and particulate matter into the atmosphere, contributing to poor air quality. Wildfires that occur are also worth mentioning, as they are a direct result of heat and drought. They release a massive amount of pollution into the air, affecting regions both close and far away. They can travel hundreds of kilometers and make the situation worse for days, if not weeks.

Air pollution in winter

We usually associate winter months with increased air pollution, as this is the time when we use cars rather than bicycles or public transportation to commute. This translates into more carbon dioxide. Moreover, fireplaces and wood stoves used to heat our homes when it’s cold outside release smoke into the atmosphere.

Nitrogen oxides found in the smoke interact with sunlight, chemical compounds, and hydrocarbons. As a result, ground-level ozone gas is created and comes into contact with particulates in the air.

What contributes even more to worse air quality in winter is the temperature inversion effect. A layer of warm air traps the cold air near the surface. That cold air may contain pollutants, such as smoke and car exhaust. This builds up smog, especially in valley regions and areas surrounded by hills.

Moreover, colder months have shorter days, and UV radiation from the sun is weaker, which tremendously slows down the natural dispersion and breakdown of pollutants. As a result, harmful elements remain in the air for longer, and the risk of respiratory irregularities increases. 

Winter air quality – why pollution levels rise when it’s cold?

Many residents wonder is air pollution worse in summer or winter, because intuitively, we associate smog mainly with the heating season. This is exactly when it becomes particularly clear why does air quality get worse in winter: fuel consumption for heating homes increases, we use cars more often and atmospheric conditions favor the accumulation of pollutants. The temperature inversion phenomenon traps cold, polluted air near the ground. Therefore, why air quality is bad in winter is rooted both in our habits and the physics of the atmosphere.

Air pollution: summer vs winter

It’s impossible to state unanimously that air pollution is worse during the summer or winter months. Some types of pollutants are particularly harmful on warm days, while others are active mainly in cold temperatures. As air temperature has an impact on the movement of air, it can also affect the movement of pollution. This means that when the temperature is high, pollutants are generally in higher altitudes.

On the other hand, car exhaust fumes and other pollutants are more visible when it’s cold outside. However, it doesn’t necessarily mean that there are more pollutants. It’s important to mention that industrial emissions remain the same throughout the year, whereas car exhaust fumes and wood burning typically increase during winter months.

Understanding the accumulation effect between summer and winter

When comparing seasons, the question often arises: why does air pollution increase during winter, given that we also experience bothersome pollution and heat in summer? In winter, we have the added effect of accumulation: solid fuel heating, increased car traffic and weaker air mass mixing. At the same time, we cannot ignore the question is there more dust in winter or summer, because in warmer months, dust blown from dry ground, road traffic or construction work is more prevalent. In the warmer months, we are also bothered by secondary aerosols and high levels of ground-level ozone.

The Takeaway

Summer pollution is more chemically reactive and irritating. Increased ozone formation contributes to that. Winter pollution, on the other hand, often includes heavier particles and toxic gases from heating sources that are not typically used during the summer season. Both seasons have profound health implications; however, local geography, city planning, and lifestyle habits can influence which season is perceived as worse.

So, when is air pollution the worst? It depends. If you reside in a city with heavy traffic and limited green spaces, winter might be more challenging in terms of pollution. However, in sunny, densely populated areas, summer smog, though less visible, might be a concern for you.

Want to learn more? Check out our entry and discover everything you should know about air pollution!