The concentration of the spores is relatively low in the winter, she/it then rises considerably in Central Europe in the summer-months (September). This depends on the higher relative humidity and the temperature as well as also from the dust-volume on that occasion in the ambient air once since microorganisms hang on to dust-particles. (With sterile-attempts [1983-85] partially became the ascertainable measured values from > 106 Particles/m3 exceeded.) The statements can be confirmed with it in the literature, where lies the number of the spores of fungus in the air between 103 to 106 per m3. Its number especially then rises been done at, if with materials, where much dust originate, as stables in barns, mills, in the wood-processing uvm. The life span of fungus-spores is dependent on the temperature, the air-speed and the sun-no-radiation in the free air. Colourless spores are destroyed by the ultraviolet radiation quickly. Therefore dominates pigmented spores of Alternaria and Cladosporium, blackness-fungi, that grow everywhere on rotting organic material. All microorganisms begin its life as individual cell or spore and exist in the natural environment-air. Orders of magnitude of 1000 to 10.000 fungus-spores / m³ environment-air can be dependent in stock on that occasion seasonally. Opposite it, the number of bacterias is not dependent on the nutrient-offer, the humidity and temperature in the air. The bacterial count in the air is no printout of growth and augmentation, she/it is determined by the share of the air pollution (dust-particles). This is climate, settling-density, year and time of day, base-coat and landscape-structure, dependent on the geographical conditions, weathers, on the other hand. Usually, bacterias remain in direct proximity of its origin. 
Through this aerates the building takes place inevitably also a diminution of the concentration at microorganisms and contaminant-occurrences. Normally, an attenuation should take place. If the concentration is higher into direct proximity of the building or at the outside, becomes so living or dead fungus-parts in aired, analogously this involves also for bacterias to. Sensitive inhabitants, further under point 5.1.) should consider this aspect. One can take on influx consciously that the concentration of microorganisms in the outside-area essentially doesn't exceed the natural scope. That is, for example, the avoidance of optimal life-conditions for bacterias, seaweeds and fungi, for example. The assignment of pathogenic bacterias through the air admittedly is possible, however in general rare. Bacterias like already require named dust or most choicest attaches water-drips (coughs or sneezing) she/it at this and is "transported" so. Under the influx of the sunlight, these are destroyed quickly.