10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Influence of Occupant Characteristics on Indoor Microbiome
DAHAE SEONG, Shamia Hoque, USC
Abstract Number: 1459 Working Group: Bioaerosols
Abstract Indoor air is an evolving environment that changes with time, occupant behavior, building interior, and ventilation design. Numerous studies have investigated the impact of surrounding environments to determine how they influence the indoor conditions and how they interact with each other. Recent studies have revealed that human activity and occupancy highly influence indoor microbial composition and concentration. The influence of male to female gender rations has been observed at university dormitories and restrooms. Some microbes have been revealed to show a gender signature, such as Corynebacterium and Lactobacillus, typically identified at specific gender assigned rest rooms. Although indoor microbes have been widely studied at diverse locations we are still trying to assign sources to the components of the microbiome. In this study we look at the impact of different age groups, room function and seasonal changes. Sampling is being conducted across different school buildings at different locations. The schools are classified into elementary school, high school, and university. The objective of the study is to investigate how the microbial composition and their concentrations vary (if any) with different age groups and different usage of room. Since sampling is being conducted over a long period of time, the effects of weather will also be assessed.
The age groups are classified into three groups, childhood (4 to 11 years old), adolescence (12 to 18 years old), and adulthood (older than 18 years). Ambient air and surfaces are sampled. Bacteria from ambient air are collected through a passive sampling using Petri dishes filled with nutrient agar. Surface samples are collected using sterile swabs. Samples have been being collected on October 2017, December 2017 and January 2018. Samplings at all schools were conducted in the classroom, boy’s and girl’s locker rooms, and libraries which students consistently use, but have a different occupancy rate and gender-ratios. The presence and persistence of microbes can be influenced by the surface types present. Since the most predominant surface materials in the schools were wood, plastics, and metal, three different materials were selected as swab locations. HVAC systems were operating during the sampling time.
Analysis of the results show that inhalable particles under 0.5 µm were dominant in both locker rooms. The number of particles in the boy’s locker room was much higher than the girl’s locker room sampled at high schools. The microbial concentration in the samples from both high school and university locations show that that male-occupied rooms had more variation in the microbiome than rooms routinely used only by females (male and female locker rooms). This was also observed in another study and this could be because men scattered skin cells more than women. Predominant indoor microorganisms, Staphylococcus, Micrococcus, and Bacillus, were identified in all the locker rooms and classrooms. At all sampling locations, except one classroom, Staphylococcus was dominant. Micrococcus sp., Bacillus sp., Rhodotorula sp., and Aerococcus were the other species identified. The sampling was conducted during a cold spell. The weather influence was noticed on the microbial composition which included Rhodotorula sp., and Aerococcus. These species grow more at lower temperature than others such as Bacillus which was also identified. For a more in depth understanding of the age impact, more samples from schools with children in the age groups of 4 – 11 have to be collected. The ultimate goal is to determine if there is a correlation between the microbiome diversity and quantity to occupant and building characteristics.