A study of possibility the air conditioning system in a car to become a bioaerosol generator

Abstract

A group of 42 cars with installed air conditioning systems was checked in terms of bioaerosol delivered into the cabin through the ventilated air. The bioaerosol in question comprised mesophilic and psychrophilic bacteria and fungi. Ratios of bioaerosol concentration in the inner and outer air were calculated. For the cars under tests, the inner bioaerosol concentrations were generally smaller than those from the outside air, except for few cases, mostly for mesophilic bacteria. The achieved results do not show any specific correlation between the inner to outer concentration ratios and actual air temperature and air humidity for all types of measured bioaerosols. Also, the age of the cars itself was not possible to correlate with the changes of the bioaerosols concentrations within the inner air. The highest observed bioaerosol concentration ratio achieved value of 8,50 for mesophilic bacteria. The zero concentrations in the cabin entering air was found 8 times for mesophilic bacteria, 2 times for psychrophilic bacteria and 3 times for fungi. It was concluded that the actual bioaerosol concentration in the air coming out from the air conditioning channels depended on the given car history. This comprised of exploitation conditions, outer air conditions with the met level of airborne particles, their nature, probably also air channels and filter construction and frequency of the earlier performed servicing of the air conditioning system. All these factors together during all the vehicle exploitation time period, influence and form the bio composition of the particulates in the air entering the car cabin.