Association of indoor and outdoor bacterial and fungal bioaerosols with respiratory symtoms among children aged 10-11 years in selected schools in Hulu Langat, Malaysia

The presence of bacterial and fungal bioaerosols is almost inevitable in most enclosed environment and they are not all pathogenic as some may exist as a normal flora while some are airborne pathogens. This study was designed to characterize the type and bacterial and fungal bioaerosol concentrations in primary schools and its association with respiratory symptoms among school children. Environmental monitoring and bioaerosol sampling were conducted in five randomly selected schools. The sampling device used for monitoring bacteria and fungal bioaerosol was the Duo SAS Super 360 microbiological air sampler and Q-Trak IAQ Monitor was used for monitoring the temperature and relative humidity. Identification of bacteria and fungi was done using both conventional and molecular methods. Modified ISAAC questionnaire was distributed and completed by 201 school children together with their parents for respiratory health assessment. Normal flora bacteria was the most frequently isolated bacteria including Staphylococcus spp., Pseudomonas spp. and Bacillus spp. Terribacillus spp. found in this study has never been reported from any other studies. The most frequently isolated fungal genera were Aspergillus, Penicillium, Fusarium, Rhizopus and Zygomycetes. The average bacterial concentration in indoor and outdoor air were 1025(±612) CFU/m3 and 1473(±1261) CFU/m3,respectively while the average fungal bioaerosol concentration in indoor and outdoor air were 292(±83) CFU/m3 and 401(±235) CFU/m3, respectively. The percentages of bacterial and fungal samples that were within the ACGIH recommended levels were 44% and 33.8% respectively. Ratio of indoor to outdoor fungi concentration was below 1.0 suggesting minimal inside generative source for fungal bioaerosols. The ratio of indoor to outdoor bacteria concentration was approaching 1.0 suggesting the presence of potential internal generative source of microorganisms and inadequate ventilation. Building occupants might be one of the potential sources of microorganisms in indoor air as bacteria concentration without occupants was significantly lower than with occupants (p<0.05). School children commonly reported chronic cough with phlegm (29.9%), itchy watery eyes and nose (28.4%) and wheezing or whistling in chest (20.9%). Allergy to dust recorded the highest prevalence (35.8%) compared to the other allergies. The most frequently isolated bacteria Staphylococcus spp. and Bacillus spp. showed no association with respiratory symptoms except with sore throat. Aspergillus spp. showed association with common reported respiratory symptoms among school children compared to Penicillium and Rhizopus spp. exposure. Asthma and allergy showed association with parental history of asthma and allergy but no association with bioaerosol exposure. Exposure to high fungi concentration that is more than 500CFU/m3 in indoor air of school environment was the prominent risk factors associated with respiratory symptoms reported by school children as compared to bacteria concentration and types of bioaerosols is dated.

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