Is air conditioning a health hazard?

Filter Air conditioning systems are present in many modern cars. The advantages of air conditioning such as comfort in the summer time are well-known. However, the potential risk of contamination of the air in the cabin by microorganisms by the air conditioning system has yet rarely been examined. A new study looked at influence of AC systems in cars on the quality of filtered air from the outside and air re-circulating from the car’s cabin under various conditions. The result?

The microbiological quality of air improves when using air conditioning systems in cars. BMC Infectious Diseases 2010, 10: 146 doi:10.1186/1471-2334-10-146
Air conditioning systems are a common feature in automobiles these days. However, its impact on the number of particles and microorganisms inside the vehicle – and by this its impact on the risk of an allergic reaction – is yet unknown. Over a time period of 30 months, the quality of air was investigated in three different types of car that were all equipped with a automatic air conditioning system. Operation modes using fresh air from outside the car as well as circulating air from inside the car were examined. The total number of microorganisms and the number of mold spores were measured by impaction in a high flow air sampler. Particles of 0.5 to 5.0 µm diameter were counted by a laser particle counter device. Overall 32 occasions of sampling were performed. The concentration of microorganisms outside the cars was always higher than it was inside the cars. Few minutes after starting the air conditioning system the total number of microorganisms was reduced by 81%, the number of mold spores was reduced by 83.3%, and the number of particles was reduced by 87%. There were no significant differences neither between the types of cars nor between the types of operation mode of the air conditioning system (fresh air vs. circulating air). All parameters that were looked for in this study improved during utilization of the car’s air conditioning system. We believe that the risk of an allergic reaction will be reduced during use also. Nevertheless, we recommend regular maintenance of the system and replacement of older filters after defined changing intervals.


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