It's cold and dark outside, but a warm fire is blazing inside. With a fireplace, a blanket and a hot cup of tea in your hand, wintertime can be really cozy. But what we don't see: Our fireplaces and wood-burning stoves are major emitters of pollutants, especially particulate matter. This is another reason why particulate matter pollution in the outdoor air is a major problem, especially in the winter months. Ultimately, it has a direct impact on our health and well-being.

In summer, the fine dust values or PM10 values (particulate matter up to 10 micrometers) in Germany are often below 50 µg/m³. The European daily limit value is currently 40 µg/m³. In winter, however, more than 100 µg/m³ are frequently measured, in cities such as Stuttgart even 188 µg/m³, i.e. more than four times higher than the EU limit value. Since 2021, the WHO has even recommended only 15 µg/m³, although this is not legally ^binding1.

Wood-burning stoves are therefore a factor in the high levels of particulate matter in the air in winter. In Germany, for example, they are responsible for 10 to 20 percent of particulate matter in the winter ^months2. In Poland, charcoal heating is even more common than in other European countries, which is why particulate matter levels in many districts regularly exceed the EU limit values - especially in winter, of course. The cosy wood-burning stove in many living rooms can emit up to 500 mg of particulate matter per hour - equivalent to the emissions of a Euro 6 car over a distance of 100 kilometers^.3

Traffic also contributes massively to the high concentration of particulate matter in the outdoor air in winter. From November onwards, many commuters switch from bicycles or public transport to cars, and there are generally more vehicles on the road. Due to this increased volume of traffic and the weather conditions, there are often traffic jams or gridlocked traffic - cars are on the road for longer. In addition, many drivers leave their vehicles running in cold temperatures, which causes them to emit a large amount of pollutants.

In winter, however, climatic conditions are added to our own behavior. These are also responsible for high levels of particulate pollution. Thermal inversions regularly occur in winter, where cold layers of air on the earth's surface are overlaid by warm ones. The cold, polluted air is therefore trapped. Especially in cities located in basins, there is no vertical exchange of air, which is essential for the removal of ^pollutants4. The result: a significant increase in the concentration of particulate matter.

An increased concentration of particulate matter has a significant impact on people's health and well-being. The WHO estimates that several million premature deaths occur every year due to particulate matter. People often report acute symptoms, such as coughing fits and breathing difficulties, especially in winter in heavily polluted areas. Furthermore, the small particles can enter our lungs and bloodstream and cause asthma, heart attacks or lung cancer. The risk of miscarriages or stillbirths, neurological diseases or dementia also increases due to poor air ^quality5.

Air filters protect us indoors from polluted outdoor air

Particulate matter pollution in the outdoor air is a serious problem that is exacerbated in winter by our behavior and climatic conditions. To protect people's health, it is essential to take appropriate measures to filter this air before it enters Air into our interiors.

Properly designed and optimized ventilation and air conditioning systems are used to improve indoor air quality. Filter inserts make a significant contribution to a healthy and pleasant indoor climate by effectively removing particles such as dust, bacteria and smoke from the outside air.

For the best possible filter result, several filter stages with different filter efficiencies and configurations are often used. General air filters such as pocket filter, filter mats, panel filter and compact filter are used for coarse and fine dust filtration. Special air filters such as HEPA or ULPA filter can filter bacteria and viruses from the air - a decisive factor in hospitals or other environments with a high level of viruses and bacteria. Activated Carbon Filters bind unpleasant odors and pollutants such as VOCs that are produced by everyday products. These air filters ensure better air in Airports or in restaurants and commercial kitchens.

Cabin air filters protect vehicle occupants

It is not only inside buildings that we need to pay attention to our air quality. In normal operation, Ventilation of a car draws around 300,000 liters of air into the vehicle interior every hour - and of course pollutants such as fine dust, pollen and soot along with it. As a result, vehicle occupants can be up to five times more polluted than passers-by on the roadside.

High-quality cabin air filters and their regular replacement are therefore essential. In addition to many classic cabin air filters, Hengst also offers the Cabin air filter Blue.care+, which effectively protects against viruses, bacteria and odors as well as fine dust. As an innovative solution, we have developed the Electrified cabin air filter Blue.ion, which protects against even the finest particles (PM1 and smaller) and, thanks to ionization and polarization technologies, offers a permanently high and energy-efficient filtration performance.

• 1: Air pollution: EU adopts lower particulate matter and NO₂ limits. ADAC, 2024
• 2: Particulate matter pollution from wood-burning stoves. Federal Environment Agency, Federal Republic of Germany, 2023.
• 3: Heating with wood. Federal Environment Agency, Federal Republic of Germany, 2021.
• 4: How Weather Affects Air Quality. UCAR, Center for Science Education.
• 5: Health consequences of air pollution on populations. WHO, 2024.