It is generally agreed upon that pathogenic microorganisms emitted from livestock buildings in wet and dry aerosols may cause animal and human diseases by airborne transmission. The processes involved in the transmission of microorganisms via the airborne route are still not well revealed. Airborne microorganisms are exposed to meteorological factors, particularly temperature, humidity, wind velocity and solar radiation. These factors may have significant effects on the survival and spreading of these micro-organisms. Effects may be different for different species. The objective of this study is to investigate the effects of temperature and humidity on the survival of different bacteria types in the air.