Bioaerosols: Assessment of indoor air quality in Mexico’s hydrocarbon industry

Introduction
Bioaerosols are airborne particles originating from biological sources. Examples of these particles include fungi, bacteria, viruses, mycotoxins, and pollen. Bioaerosols can be especially problematic in indoor environments, causing a variety of human illnesses. In the present study, quantification and identification of bioaerosols (bacteria and fungi, specifically) were carried out in office buildings of the hydrocarbon industry located in central and northern Mexico, in order to evaluate their presence in indoor common use areas. 

Methods
The study was conducted from August, 2010 to June, 2011. An environmental slit-to-agar sampler (flow rate 140 L/min) was placed in indoor common use areas such as offices, bathrooms, dining rooms, laboratories and warehouses. Outdoor environments were used as a control for each site. Dampness, temperature, number of staff and cleanliness in each area were measured. Molecular methods were used for the identification of the isolates.

Results
Eleven work sites were evaluated in the states of Guanajuato, Michoacán, Coahuila, Nuevo Leon and Tamaulipas. Worksites near contaminated water bodies and urban zones presented elevated bioaerosols concentration. Bathrooms were the indoor sites with the highest concentrations of bioaerosols (164-2240 CFU/m3 for fungi and 44-706 CFU/m3 for bacteria), followed by offices and dining rooms. Dampness and number of staff were factors associated with the concentration of bioaerosols. Aspergillus, Penicillium y Fusarium were the most represented genera. 

Discussion
Assessments of air quality of worksites most commonly focus on the concentration of volatile organic compounds, often excluding the microbiological aspects in indoor sites. To limit bioaerosols concentrations, it is important to properly clean and ensure suitable ventilation in heavily populated areas of the workplace.