A distinction is made between PM10 and PM2.5 (PM, particulate matter) with a maximum diameter of 10 and 2.5 micrometers (µm) respectively, and ultrafine particles with a diameter of less than 0.1 µm.

Particulate matter is released from various natural and anthropogenic sources. The latter include domestic combustion and power generation plants, commercial enterprises, industrial plants and especially road traffic (diesel soot, abrasion from tires and brakes). Nowadays, annual average PM10 values of between 15 and 20 µg/m³ are common. A trend of decreasing concentrations is observed, but the number of the finest particles is increasing dramatically.

In closed rooms, tobacco smoke, emissions from laser printers (up to 2 billion particles per printed page) and people themselves are sources of particulate pollution. People emit particles every time they move. When speaking and breathing, emissions of aerosols are unavoidable. These aerosols can not only transport viruses or bacteria, but also evaporate very quickly in the room air, leaving behind tiny particles of salts and bodily secretions. Sensitive products, such as optical or electronic components, or sterile medical or pharmaceutical products must therefore be protected from people and their particle and aerosol emissions. However, people are usually essential for final assembly, packaging or filling, which means that workplaces are subject to special challenges such as particle and germ freedom.

The separation of fine dust poses a real technical challenge. These can only be removed from the indoor air through proper cleaning of the room air. Filter technologies have proven to be a particularly cost-effective alternative, as they can be retrofitted if necessary. This applies to complex cleanrooms as well as smaller filter units, the so-called laminar flow box, as both systems are based on the same filter technology.

A laminar flow box, for example, such as the FBS series from Spetec, a manufacturer of filter technology with decades of experience, uses high-performance class H14 filters. This allows 99.995 percent of all fine dust particles to be efficiently separated (based on a particle size of 0.12 μm), which means that the air quality in the interior can be improved by at least 10,000 times compared to the ambient air in the production area. The use of a laminar flow box is therefore an effective measure in the fight against an increasing number of particles and is therefore also the most effective way of protecting the quality and function of products.