Spring is a time for renewal – but for many companies and workplaces, the change of season also means an unwanted change in the indoor climate. As we move from the stable, cold and dry conditions of winter to the more dynamic climate of spring, the amount of dust in the air increases and microorganisms are set in motion.

You may notice that the air feels heavier, that dust collects faster on surfaces and that there is an unpleasant odor that was not there during the winter. In workshops, warehouses, production halls and office spaces, this can manifest itself as increased particle loads, drier air and more frequent complaints of fatigue and eye and respiratory irritation.

Bacteria in the air – a natural part of the indoor climate

Indoor air is never sterile. It always contains a mix of small, invisible particles of biological origin. Typically, these organisms are found in the air:

Bacteria and bacterial fragments
Fungal spores from damp materials or outdoor environment
Pollen grains drawn in through ventilation and open doors
Microorganisms bound to dust particles
Organic compounds from production processes, packaging or stored products

In premises with activity – whether it’s welding, packing, material handling or just daily traffic – these particles become easily airborne. They can hang in the air for several hours and end up in the breathing zone of those working there. For most people, this is unproblematic in small quantities, but as the concentration increases, both perceived comfort and actual air quality are affected.

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Why do dust and microorganisms increase towards spring?

Several mechanisms interact when winter lets go:

Increasing temperature
When the outside temperature rises, biological activity increases both indoors and outdoors. Microorganisms that have lain dormant in dust and materials throughout the winter are given better growth conditions. The increase in temperature alone can accelerate the spread of bacteria and fungi in areas where there is organic material – for example, in warehouses with wood, paper or textiles.
Collected winter dust
During the winter, indoor air is often very dry (relative humidity can be below 30%). Fine dust particles bind poorly and settle as a thin, loose layer on shelves, floors, machines and ceilings. When activity in the building increases in the spring, this accumulated dust is stirred up again. The result is a noticeable increase in airborne particles.
More air exchange and external traffic
Spring brings open doors, more frequent loading and unloading, and often more natural ventilation. At the same time, the amount of pollen outside increases dramatically. Bacteria and fungal spores from soil and vegetation are brought into the building along with exhaust fumes and road dust.
Unstable humidity
The transition period between winter and spring is characterized by large fluctuations in relative humidity – from dry, cold days to sudden rain showers and milder air. These variations affect how dust particles behave: Low humidity makes them lighter and more airborne, while rapid changes can lead to condensation on cold surfaces, creating a breeding ground for microorganisms.

Impact on air quality, health and production

Increased levels of dust and bacteria in indoor air have real consequences:

Perceived comfort decreases. Many people report dryness in the throat and nose, itchy eyes and general fatigue.
The need for cleaning increases significantly – often without overcoming the problem in the long term.
Dust exposure in the breathing zone can exceed recommended limit values, especially in workshops and production.
Production stability is affected: in sensitive processes (food, electronics, pharmaceuticals), particles and microorganisms can increase the risk of contamination.
Sick leave can increase when the respiratory and immune systems are subjected to extra strain.

In the worst case, this contributes to chronic ailments such as allergy-like symptoms – which in turn affects both well-being and productivity.

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At a humidity below 40%, pathogens such as bacteria, fungi and viruses persist longer.
Dust particles, bacteria, fungi and viruses spread throughout the room and remain airborne for a long time.
Dry mucous membranes offer little protection, and dust particles and pathogens can enter the lungs.

Bacteria, fungi and viruses have the shortest lifespan at a humidity of 40-60%.
Dust particles, bacteria, fungi and viruses bind to water particles, causing them to fall to the ground.
Moist mucous membranes provide natural protection, trapping dust particles and pathogens.

Stable humidity – the key to better control

The most effective and preventive measure is to ensure a stable and correct humidity level throughout the year. When relative humidity is kept between 40 and 60%, several positive things happen at the same time:

Fine dust particles bind better and are swirled up to a much lesser extent.
Microorganisms have poorer growth conditions (most bacteria and fungi thrive best at extreme humidity levels).
Materials and products remain stable – wood doesn’t swell, paper doesn’t wrinkle, electronics have less static electricity.
The air quality is perceived as smoother and the need for intensive cleaning is reduced.

Modern humidification systems (such as adiabatic or steam-based solutions with precise control) make it possible to maintain this level without energy loss or condensation problems. Combined with good ventilation and regular filter changes, the indoor climate becomes robust against seasonal variations.
Read more about Humidification and Dust control.

Systematic work pays off

The change of season from winter to spring reveals how vulnerable the indoor climate is. What many perceive as a “normal spring feeling” in the building is actually a reminder that temperature, humidity and activity need to be actively managed. By understanding the connection between biological processes, accumulated dust and air exchange, companies can take action in time.

Those who invest in a stable indoor climate – through humidification and routine monitoring – experience fewer complaints, less sick leave and more predictable production. Good air quality isn’t a luxury; it’s a prerequisite for a healthy and efficient working environment all year round. With spring just around the corner, it’s worth taking a few minutes to check the status of your own indoor climate.

Do you want to get control of the dust in your air? Small measures now can save both health and costs over time.

Get in touch for more information and a non-binding assessment.

Relevant articles:

https://www.epa.gov/indoor-air-quality-iaq/indoor-air-quality-and-changing-outdoor-environments

https://pmc.ncbi.nlm.nih.gov/articles/PMC3497365/

https://pmc.ncbi.nlm.nih.gov/articles/PMC10193533/

https://pmc.ncbi.nlm.nih.gov/articles/PMC8254435/

https://www.epa.gov/indoor-air-quality-iaq/biological-contaminants-and-indoor-air-quality