Need an account? Click here to sign up. Download Free PDF. Fungal colonization of air-conditioning systems Archives of Biological Sciences, Ljaljevic Grbic. A short summary of this paper. Download Download PDF. Translate PDF. Rarely, indoor fungi may cause human infections, but more commonly allergenic responses ranging from pneumonitis to asthma-like symptoms. From all air conditioner filters analyzed, 16 fungal taxa were isolated and identified. Aspergillus fumigatus causes more lethal infections worldwide than any other mold.

Air-conditioning filters that adsorb moisture and volatile organics appear to provide suitable substrates for fungal colonization. It is important to stress that fungal colonization of air-conditioning systems should not be ignored, espe- cially in hospital environments. Key words: Indoor air, air-conditioning filters, micromycetes, human health Udc Cellulose Fungi inhabit nearly all terrestrial environments. In and synthetic fibers probably come from indoor this regard, the interiors of human dwellings and sources, while the other components most likely workspaces are no exception.

The mycobiota of originate from outdoor sources. Insulation materi- human-inhabited indoor environments consists of als also absorb moisture and volatile organics and a distinctive group of organisms that collectively are provide suitable substrates for fungal colonization not normally encountered elsewhere. These organics represent tion occurs as a result of the ongoing elutriation of excellent nutrients for fungal growth, with the result airborne organic and inorganic particulate matter that air filters harbor an abundance of fungal hyphae that originates from a multiplicity of indoor and and spores Yo u n g , Dust and microorgan- outdoor sources S c o t t , House dust is a isms may accumulate in supply air ducts during fibrous material composed primarily of a matrix installation or later from the outdoor air due to of textile fibers, hairs, and shed epithelial debris leakages between the filter cassette and the assembly Scott, Fungi commonly isolated from indoor frame, or from insufficient efficiency of the filter air include Alternaria, Aspergillus, Aureobasidium, P a s a n e n et al.

Cladosporium, and Penicillium species. Many of these species may contaminate indoor air through Human infections caused by indoor fungi are heating, ventilating, and air-conditioning systems very seldom because of the highly efficient defense S i m o n s et al. It is well known that venti- mechanisms of human cells, such as the cell-medi- lation systems, even those without water-containing ated response P e r d e l i et al. However, components, may act as a potential microbial source conidia and fragments of hyphae may sometimes in indoor air P a s a n e n et al.

Filters are cause allergenic responses, and some metabolites porous soft insulation material very often used in produced by fungi may be toxic or have immu- air-conditioning systems. Direct microscopic exam- nomodulating activity in humans S i m o n s et ination of air filters reveals pollen particles, cellulose al. Fungal fungi and consequent onset of infection, sometimes colonies formed on the medium were identified with fatal effects P e r d e l i et al.

There are on the basis of both macroscopic and microscopic reports that four patients died and 11 contracted characteristics of each isolated colony using identifi- the respiratory disease aspergillosis at the Alcala de cation keys A i n s w o r t h et al. The disease E l l i s and E l l i s , ; P i t t , ; R a p e r , and was caused by inhaling the spores of Aspergillus F e n n e l From all dust samples analyzed from classrooms, offices, and hospital air-conditionning systems, six Fifteen dust samples were collected from air- fungal genera with different numbers of species were conditioning filters from school classrooms and recorded: Cladosporium, Penicillium, Aspergillus, offices.

Also, five swab samples were collected from Alternaria, Epiccocum, and one Ascomycotyna from an air conditioner in a hospital surgical ward. None the order Sphaeriales Table 1. The fungal colonies of the analyzed filters from classrooms and offices isolated from different sources were characterized had been removed or cleaned for two years Fig. The genus a month on a regular basis. Aspergillus with five species was the most frequent Tabel 1, Fig.

The abundance of fungal Direct examination colonies was much higher in classrooms and offices The tape lift technique used for direct examina- than in the hospital. Aspergillus and Penicillium tion allows for immediate determination of the pres- species were dominant.

Alternaria alternata and ence of fungal spores and identification of the types Cladosporium cladosporioides were the most frequent of fungi present. Direct examinations should only be dematiaceous fungi Fig. Fungal growth was used to sample visible mold growth in contaminated quantified by the number of CFUs.

Culturable spore air-conditioning filters. In central Finland, culturable and total pressure, holding only the tape edges, after which fungi in dust accumulated in air ducts in single-fam- they were put on slides for light microscopy.

The diver- dust. Sub-samples 0. Dilution series were prepared themselves. Fungal structures from air conditioner filter dust: a two years uncleaned air conditioner filter; b the conidial chain of Aspergillus ochraceus; c conidiophores with terminal conidium of Cladosporium sphaeospermum; d mycelia with chlamydospores inside filter fiber; e chlamidospore; f conidia of Alternaria sp. Only two fungal species were found infections, most commonly A. Spores in samples from the hospital units, with very low from these species are widespread in the environ- colony abundance.

This result is worrying because ment, occurring in soil, in dust, and in outdoor and one of the two isolated species was Aspergillus versi- indoor air. Known as aspergillosus, fungal infection color Fig. Aspergillus is a large genus of fungal with Aspergillus ranges from the benign to the fatal. Micromycetes isolated from air conditioner filter dust: a fungal colonies on MA; b Aspergillus ochraceus; c Alternaria alternata; d Cladosporium cladosporioides; e As- pergillus versicolor; f Aspergillus fumigatus.

Dissemination tract relatively benign infections of the lungs and to the brain, gastrointestinal tract, and other organs sinuses. Micromycetes isolated from analyzed filter dust of air- opportunistic infection in immunocompromised conditioning systems.

Sussman Academic Press, New Penicillium veruccosum var. Penicillium spp. For example, about Cars are our number one source of mobility, and road transport is the most common means of transport in the world. Every day, thousands of people spend many hours in different types of road transport vehicles e. Professional drivers e. To improve our travel comfort, cars are equipped with air-conditioning AC installations.

The first air-conditioning system installed into a vehicle took place in in the USA. Since then, an increase in the number of cars equipped with AC systems has been systematically observed.

The main task of an automotive AC system is to ensure the appropriate quality of the air inside the car. The most important air parameters, which can be regulated in the air-conditioned interior, are temperature and relative humidity.

A well-functioning air-conditioning system guarantees driver and passenger comfort by, for example, providing cold air during the summer, as well as protection from particle pollution of the atmospheric air. The use of an AC system also usually results in a decrease in the presence of microbial contaminants inside the vehicle Vonberg et al. In practice, modern automotive air-conditioning installations become quite often an active source of emission of harmful biological agents mainly bacteria and fungi.

This development of microbes is a result of surface contamination of the AC system, strongly supported by the increase in air humidity caused by the small diameter of air-conditioning cords, air cleaners, air refrigerators etc. Some microbial contaminants are able to easily create a biofilm in the air-conditioning ducts and as such can be distributed around the other installation elements, as well as within the car interior itself Simmons et al.

The longer the automotive AC installation is used, the more likely it will become a source of adverse air pollution of microbial origin in the car cabin. Exposure to bioaerosols may lead to adverse health effects, ranging from simple irritations, through allergic reactions, to infectious diseases or toxic response Douwes et al.

Numerous studies prove that exposure to high concentrations of microorganisms in the air is often linked to asthma, rhinitis and pneumonia. Bioaerosols might also present a risk to human health since they can be a source of harmful structures and substances exhibiting immunological reactivity allergens, mycotoxins, endotoxins and other microbial cell fragments in the air Fiegel et al.

Proper servicing of automotive air-conditioning installations requires systematic maintenance. It is advised to regularly replace the cabin filters, clean and disinfect the air ducts, evaporator and air inlets of the motor-car body and control the permeability of the condensation extracting canal from the air-conditioning installation evaporator. Various methods are used to clean air-conditioning installations: chemical use of disinfectants , physical ozonisation and chemicophysical use of disinfectants combined with ultrasounds.

Regular cleaning of air-conditioning installations significantly influences the maintenance process and, therefore, the indoor air quality. In all of the vehicles examined, the tightness of the air-conditioning installation was checked, the coolant level was inspected and topped up, cabin filters were replaced and the dehumidifier and evaporator were inspected before the specific disinfection method was applied.

The ozonisation process ran for 20 min in every car, and after approx. An ozone generator was used for ozonisation. Application of a chemical disinfectant containing 2-propanol 1—2. Manual single-zone air-conditioner, controlled directly by the driver; the temperature regulation was performed by mixing hot air from the air heater with cold air; the driver was unable to precisely set the temperature inside the car.

Automatic air-conditioner, controlled by an electronic system using readings from the car sensors e. Detailed characteristics of the examined vehicles are provided as supplemental documentation Table S1. Air samples were collected before and after disinfection of the AC systems in the cars under study. The viable understood here as culturable bioaerosol samples were taken using a single-stage MAS impactor model Eco, Merck, Germany.

During the tests, the impactor was placed within a zone of about 0. Air samples were collected on agar media. The taxonomical origin of isolated pathogens was additionally confirmed using molecular techniques. Filamentous fungi were initially stained with lactophenol and subsequently identified according to their morphology using several identification keys Fisher and Cook ; Samson et al.

DNA isolation included preincubation with lysozyme and lysostaphin. The p values below 0. The mean concentrations of bacterial and fungal aerosols measured using the MAS impactor in the studied cars and in outdoor background in the air outside the cars are presented in Table 1. Using the Spearman correlation coefficient with the impact of the mileage, the type of air-conditioning system 1-, 2-, 4-zone and manual , type of car body SUV, sedan, estate and type of upholstery fabric, leather for concentrations of microorganisms in the air of the tested vehicles were evaluated.

Along with the high number of kilometres travelled, an increase in the concentration of bacterial fungal aerosols in the studied vehicles was observed before the air-conditioning service. SUVs have lower bacterial concentrations than sedans and estate cars. No such differences were observed in the concentration of fungi. It was also found that the type of AC system and the type of upholstery did not significantly determine the observed concentrations of bacterial and fungal aerosols in the tested vehicles.

The use of ozone as a disinfectant resulted in an average reduction of bacterial and fungal aerosol concentrations of In turn, the manual application of a chemical disinfectant in the AC systems of the tested cars resulted in an average decrease in bacterial and fungal aerosol concentrations of The use of the ozonisation method combined with the manual application of a chemical disinfectant was the most effective in AC system cleaning, reducing the bacterial and fungal aerosol concentrations in car cabins by Microclimate parameters did not significantly determine the observed bioaerosol concentrations in all the tested cars.

All bacterial and fungal strains isolated from the air of examined cars are provided as supplemental documentation Table S2 and S3. A total number of 28 bacterial species belonging to 10 genera and 31 fungal species from 18 genera were identified in the air of car cabins before the AC service.

Among the most common fungal species were those from Penicillium , Aspergillus and Cladosporium genera. In car cabins where manual application of a chemical disinfectant foam was performed as simultaneous ozonisation and application of a chemical disinfectant foam, Aspergillus fumigates were not detected. No presence of Bacillus subtilis was found in the cars under study after an AC service.

Each of the tested AC service methods decreased the taxonomical diversity of the car cabin microbiota. Only 16 bacterial species from 6 genera and 13 fungal species from 11 genera were identified in car cabins after ozonisation. In the car cabins after disinfectant application with ultrasounds, 17 bacterial species from 7 genera and 15 fungal species from 9 genera were identified.

A total number of 19 bacterial species from 8 genera and 15 fungal species from 8 genera were identified in car cabins after chemical foam service of the AC systems. The samples taken after the AC service by means of chemical and ozonisation methods presented 19 species of bacteria from 8 genera and 15 species of fungi from 8 genera. The percentage shares of particular groups of bacteria and fungi in relation to the whole microbiota identified in the studied cars are presented in Fig.

Yeasts, nonsporing Gram-positive rods and actinomycetes were the smallest fractions of identified microorganisms in studied cars. The species composition of airborne microbiota in cars before the AC service was similar to that observed in cars after the AC service, except of actinomycetes, which were not detected after AC service using ozonisation and a chemical disinfectant. Cars are nowadays by far the most common means of transport. People spend a great deal of time in them, so the quality of their indoor air is of great importance to health.

According to the literature, the use of an AC system usually decreases bioaerosol concentrations inside the vehicle. Sowiak et al. Similar findings were observed by Wang et al. An AC system which has been improperly maintained long-term operation of filters or lack of systematic disinfection may be a source of additional unwanted contamination of the air in cars. As already shown, a constant accumulation of various contaminants e.

On the basis of the results of our study, it can be concluded that all four methods of servicing of automotive air-conditioning systems were efficient in the reduction of microbial contamination of the air inside the vehicle cabins.

The most prominent purification effect was observed for two methods, namely ozonisation combined with the application of a chemical disinfectant foam and spraying of a chemical disinfectant using ultrasounds. Ozone has well-documented antibacterial properties and can be used to inactivate a wide range of microorganisms, including viruses and bacteria, which can be resistant to other disinfectants Kim et al. This gas can effectively penetrate the hard-to-reach areas of air-conditioning ducts and all other indoor spaces, making it possible to achieve a very high level of disinfection Otter et al.

However, as a highly reactive gas, ozone levels should never exceed the level of 0. Biocides used for the disinfection of air-conditioning systems usually contain 2-propanol isopropyl alcohol , i.

As already shown, 2-propanol is more effective against Staphylococcus aureus and Escherichia coli than ethanol Burcea et al. It is easily available, so it is most widely used for ventilation duct cleaning and as a disinfectant in healthcare. Alcohols are most effective when mixed with purified water. This form facilitates their diffusion through the cell membranes of microorganisms. Therefore, this process should be mechanically supported by, for example a source of ultrasounds.

The device used in our study produces high-frequency ultrasounds 1. This spraying of the disinfectant, through the inlet and outlet ducts air and ventilation of the vehicle, reaches the evaporator of the air-conditioner and cleans all the components of the air-conditioning system in cars.

Air-conditioning service engineers using this type of product must have experience and knowledge of the construction of ventilation systems in various vehicle brands. Many studies have documented the presence of many types of harmful biological agents in the air in vehicles Aquino et al.

The current airborne microorganism concentrations inside the studied cars were found to be similar to those published in other reports Lee and Jo ; Li et al. This means that car drivers and passengers may be exposed to direct contact with biological agents that are occupational hazards and which are potentially pathogenic.

The cars tested were contaminated with allergenic fungal species Aspergillus spp. The presence of fungi in high concentrations can cause the appearance of allergic reactions and various nonspecific adverse health outcomes such as sick building syndrome SBS.

The moulds of Alternaria , Aspergillus , Cladosporium , Fusarium , Rhizopus and Penicillium species are associated with allergy and respiratory problems Aquino et al. On the basis of the results obtained, it can be concluded that air-conditioning systems in cars should be regularly disinfected to eliminate bacterial and fungal contaminants that may be the cause of adverse health effects on humans. The tested methods of servicing automotive air-conditioning systems in the cars studied work so efficiently to cause a reduction of microbial contamination of the air inside the vehicle cabin.

The highest disinfection efficiency was observed for ozonisation combined with the manual application of a chemical disinfectant into the car air-conditioning system and spraying a chemical disinfectant using ultrasounds.

The qualitative analysis of the air microbiota in the cars studied indicated the presence of bacterial and fungal microorganisms which, according to the Ordinance of the Minister of Health , are classified into risk group 2. Direct contact with those microorganisms may cause adverse health effects for drivers and passengers alike.

Among the most common fungal representatives were those from the Alternaria , Aspergillus , Cladosporium and Penicillium genera. Vehicle air-conditioning systems should be systematically maintained. The whole system should be regularly disinfected to eliminate microbiological contaminants. Air Qual Atmos Health 11 10 —