What do we breathe?


Although at first glance we would not expect the presence of microorganisms in the atmosphere, they are a natural part of it. There is a relatively diverse community of microorganisms in the air, despite the fact that it is not a suitable environment for their reproduction. In particular, there are bacteria, spores of bacteria and microscopic fungi, and viruses. Microorganisms enter the air from a natural source, the air is only a passive transport medium for them, in which they do not grow, do not multiply and persist for a certain period of time. Most micro-organisms are trapped on dust particles or in drops of water or mucus in their dried cores. They are therefore part of an air aerosol.


However, the other is the settlement of the atmosphere in enclosed rooms, especially if there are people, animals or machines. The degree of contamination of the environment by micro-organisms is usually higher than in the exterior, which depends in particular on the possibility of air exchange with the outside environment (ventilation) and other factors. Indoor environments such as apartments, operations, workplaces, offices, factories, non-residential areas, animal rooms separate air from the outside atmosphere and stabilize the microbiological composition. If pathogenic microorganisms (those causing infectious diseases) enter the indoor environment together with air, they can endanger human health (mostly pathogenic bacteria). The dynamics of microorganisms occurring in the atmosphere are seasonal, depending on weather conditions, humidity and room temperature. An effective way to maintain favorable conditions for the maintenance of human health is through intensive exchange, resp. air filtration and keeping the room clean.


Not only the presence of a high number of bacteria in the air, but also microscopic filamentous fungi, referred to as fungi, is a threat to human health. The molds have always been with us, they do not have to be dangerous themselves until at some point in their lives spores are released into the surrounding environment by which they multiply. These, trapped in dust particles or aqueous aerosols, are often carried by air currents over long distances and can subsequently populate various substrates and multiply. Indoors they can settle in dust, get stuck in corners and walls, on furniture, clothes, mattresses and carpets, behind cabinets, under wallpaper, parquet, on window and window sills, on kitchen or bathroom tiles and begin with high air humidity grow and multiply intensively.


Sometimes they are revealed by color, other times they are not recognized by the naked eye. People often start searching for them when they feel stale odors or have health problems. "Fungi" are usually not visible to the eye, we only see them when they are overgrown, if there are many in the interior, it means that there is much more moisture than healthy. Their presence is manifested by coatings often reminiscent of velvet or cotton, or spots of dark, gray to black, or greenish, sometimes pale pink, orange to brownish discoloration appear in the affected areas. People respond differently to their presence, indoor exposure is higher than wildlife.


Spores of microscopic filamentous fungi that occur in the air are important allergens. Their increased incidence often causes allergic reactions in sensitive individuals in the form of frequent bronchitis, chronic cough, asthma, mucosal irritations or skin allergies. Direct contact with mold can lead to skin diseases. Regular exposure to increased concentrations of filamentous fungus spores can lead to chronic hypersensitivity of the organism and worsening allergy over time. In interiors, the presence of microscopic filamentous fungi depends on the presence of organic contamination in dust particles, available biological material (eg paper, wood, leather, cotton ...), air temperature in the range 15 - 35°C, high humidity. Water condensation and moisture on surfaces that “mold” populate are more important for their growth and reproduction than relative air humidity. The increase in the number of microscopic fiber fungi in interiors is caused not only by structural defects, improper insulation causing leakage, but also by poor housing maintenance and poor ventilation.


Increased health risk, according to the Decree of the Ministry of Health 259/2008, is represented by commonly occurring microorganisms if their number in 1 m3 of air exceeds 500 CFU (colony forming units). Since this is only a quantitative parameter, it is important to determine the type of micro-organisms.