Indoor vs. outdoor air pollution: Why indoor air quality is often worse than outdoor air
Indoor air quality (IAQ) plays a critical role in health, well-being, and productivity – yet it is often underestimated. While the measurement and improvement of outdoor air quality is legally mandated in 19 out of 27 EU countries, interior air quality is frequently overlooked (source: EVIA). This is surprising, given that we spend roughly 80 to 90 percent of our lives indoors – whether at home, in the office, at school, or on public transport (source: Umweltbundesamt). Studies reveal that the concentration of pollutants indoors is, on average, two to five times higher than outdoors – and in extreme cases, up to 100 times higher (source: EVIA). At MANN+HUMMEL, we provide efficient filtration solutions against indoor air pollution, helping people breathe freely wherever they are.
Major sources of indoor air pollution
Wherever people live and work, pollutants accumulate in the air. Without the right countermeasures, these pollutants can reach harmful concentrations, especially indoors. The critical challenge? Most of these threats are invisible.
VOCs: Emissions from furniture, paints, and cleaning products
Everyday activities such as cooking, showering, cleaning, and heating release volatile organic compounds (VOCs). These emissions are further amplified by building materials, furniture, paints, varnishes, and adhesives. Flooring, wall, and ceiling materials also contribute to VOC levels. Additionally, VOCs enter buildings through open windows, especially in urban or industrial areas with polluted outdoor air.
Fine dust (PM2.5) indoors
Indoor fine dust comes from two main sources. First, outdoor fine dust – caused by traffic, industry, or natural elements – makes its way inside through windows, doors, clothing, or shoes. Second, fine dust is also generated directly indoors, from activities like smoking, cooking, burning candles, using open fireplaces, or heating with wood. In winter, wood heating can account for up to 20 percent of indoor fine dust pollution (source: Umweltbundesamt). Unlike outdoor environments, indoor spaces lack the diluting benefit of air circulation, further intensifying pollutant levels.
Mold spores from humidity
Excess humidity fosters the growth of harmful mold spores. A family of four releases about 10 liters of moisture into the air daily – through breathing, cooking, and showering (source: Verbraucherzentrale). When condensation forms on cold surfaces, particularly in poorly ventilated spaces, the problem worsens. Older buildings and inadequately heated rooms in winter are especially vulnerable.
CO₂ build-up in modern, airtight buildings
Even modern, energy-efficient buildings can negatively affect air quality. High airtightness restricts natural ventilation, causing CO₂ and other contaminants to accumulate indoors. Ventilation remains essential for removing stale air, and our indoor air filters ensure that incoming air is free from harmful particles – enabling consistently high air quality indoors.
Different types and sizes of air pollutants
Health impacts of poor indoor air quality
Poor indoor air quality can have a wide range of negative effects on health. Short-term symptoms include headaches, fatigue, dizziness, and difficulties with concentration and focus – all of which significantly impact productivity. Long-term exposure to polluted indoor air increases the risk of allergies, asthma, and chronic respiratory diseases. According to the "Promoting Action for Healthy Indoor Air" project, approximately two million healthy life years are lost annually in the European Union due to poor indoor air quality (source: EVIA). This highlights the critical need for measures that ensure consistently clean, fresh, and healthy indoor air.
Outdoor air vs. indoor air pollution: A direct comparison
| Pollutant | Indoor Air (Ø in Germany) | Outdoor Air (Ø in Germany) |
|---|---|---|
| PM2.5 | 35 µg/m³ | 9–12 µg/m³ |
| Formaldehyde | 0.05 ppm | 0.01 ppm |
These numbers clearly show: Fine dust (PM2.5) levels indoors are, on average, nearly three times higher than outdoors (source: Umweltbundesamt). Formaldehyde, a common indoor air pollutant, also exceeds outdoor levels significantly. The indoor air quality guidelines set by Germany’s Federal Environment Agency are frequently exceeded, underscoring the urgent need for targeted air purification solutions.
Our solutions for optimal indoor air quality
Whether in offices, schools, or homes, our innovative air filtration solutions significantly improve indoor air quality. We create healthy, clean, and comfortable environments – tailored to your specific needs.
For commercial and public buildings
From high-performance indoor air filters to digital air quality monitoring, we offer a comprehensive portfolio of filtration solutions tailored to the specific needs of modern buildings. Our HVAC filters ensure maximum energy efficiency while meeting the latest sustainability and performance standards in ventilation. HEPA* filters remove even the smallest particles to deliver the highest air quality, especially in environments requiring ultra-clean air – such as life sciences, healthcare, and food production facilities. Combination filters with activated carbon or molecular filtration reliably neutralize gases, odors, VOCs, and formaldehyde found in indoor air.
- Fine dust filters for HVAC systems (A+): Maximize energy efficiency, meet current sustainability and performance standards, and reduce operating costs, helping businesses achieve their CSR (Corporate Social Responsibility) goals.
- HEPA* filters: Can even remove ultrafine particles from indoor air, ensuring a consistently clean and healthy indoor environment.
- Diverse filter media and combination filters: From HEPA* and electret filters to combination filters and advanced nanofiber technology, these solutions effectively capture common pollutants such as PM2.5, formaldehyde, VOCs, viruses, and bacteria.
- Activated carbon and molecular filtration: Effectively neutralize harmful gases, odors, and volatile organic compounds, significantly improving indoor air quality.
*High Efficiency Particulate Air Filter according to DIN ISO 29463 and EN 1822
For residential spaces (household appliances)
MANN+HUMMEL also helps increase indoor air quality at home. Our home appliances solutions ensure quiet, energy-efficient and powerful operation as well as consistently high air quality in every area of life.
- Efficient kitchen filters: Protect residents from unpleasant odors and prevent grease build-up on appliances. Especially in range hoods and downdraft systems, these filters deliver quiet operation, low energy consumption, and optimal filtration performance against a wide range of odors.
- High-efficiency filters for vacuum cleaners, robotic vacuums and power tools: When used in conjunction with the respective device, they effectively remove air pollutants such as fine dust and pollen. This ensures noticeably improved indoor air quality during construction work and is also particularly beneficial in daily use, for example, for allergy sufferers.
- FreciousComfort technology for shower toilets: Our pleated filters and regenerable activated carbon honeycombs can include a microbial coating that prevents mold growth and bacterial deposits, keeping shower toilets hygienic and odor-free.
Clean indoor air for a better quality of life: Solutions for tackling indoor air pollution
Indoor air quality is a critical factor in our health, well-being, and productivity. With our filtration solutions, we provide comprehensive protection from harmful indoor air contaminants, ensuring optimal air quality so people can live and work safely, healthily, and comfortably. For over 80 years, we’ve been setting standards with our innovative filtration technologies and custom solutions. How can we help your business?
