Bacterial community analysis of floor dust and HEPA filters in air purifiers used in office rooms in ILAS, Beijing

Abstract

Air purifiers with high-efficiency particulate air (HEPA) filters remove not only particulate matter but also airborne microorganisms in indoor environments. We investigated the bacterial community in HEPA filters (used for 1 year) and that in the floor dust of 12 office rooms in Beijing. We found that the viable bacteria proportion in the filter was significantly higher than that in the floor dust (p < 0.001). The Non-Metric Multi-Dimensional Scaling analysis showed that the bacterial communities in the filters and dust were significantly different (p = 0.001). The Chao1, Shannon-Wiener and phylogenetic diversity values in the filter were significantly higher than those in the dust (p < 0.001). The predominant bacterial classes in the filter were Alphaproteobacteria and Actinobacteria, whereas those in the dust were Bacteroidia, Clostridia and Bacilli. Human occupancy contributed more to the bacterial community in the filter than that in the dust. Klebsiella and Alloprevotella in the dust and filters positively correlated with the occupancy density. Soil bacteria contributed to a significantly higher proportion of the bacteria in the HEPA filter (p < 0.001). In contrast, human oral, indoor air and outdoor haze contributed to a higher proportion of the bacteria in the dust samples (p < 0.001, p < 0.01 and p < 0.05, respectively). As HEPA filters serve as an ecological niche for indoor bacteria, they should be carefully investigated during the assessment of indoor environmental health. People spend the majority of their time indoors, wherein air pollution levels highly correlate with outdoor pollution levels 1-6. In recent years, haze pollution, fine particulate matter (PM) in particular, has been reported to increase human mortality rates owing to the development of heart disease 7,8 , stroke, respiratory disease 9 and lung cancer 10,11. The level of air pollution in China is substantially higher than in many developed countries 12. Moreover, its threat to public health has become a serious concern, particularly concerning haze events 13. Thus, an effective technology is essential for the removal of PM from indoor environments during periods of haze. To this end, air purifiers with high-efficiency particulate air (HEPA) filters are widely used in the indoor environment, particularly in areas with heavy haze 14. People are exposed to various microbes in indoor environments. Many factors could affect indoor microbial composition, including human occupancy, occupant behavior, pets and outdoor environment 15-18. The air purifier was mainly used to remove indoor PM, partly comprising microorganisms. Microbes in the air could be transmitted to the HEPA filter in the air purifier. Suzuki et al. (2003) collected swab samples from the air purifier filters in the houses of seven healthy children with varicella. They found the varicella-zoster virus was detected in 29% of filters in air purifiers by day 3 19. Furthermore, Maus et al. (2001) studied the effect of the filters on the viability of microbes. They reported microb...

Should homes and workplaces purchase portable air filters to reduce the transmission of SARS-CoV-2 and other respiratory infections? A systematic review

“…This left two studies included in the review. One included study was conducted in Beijing in 2020 within an office setting [ 14 ]. The other study was conducted in the USA in 2019 in an emergency room [ 15 ].…”

Calidad microbiológica del aire en un Centro Comunitario de Salud Familiar de Talcahuano, Región del Biobío, Chile

“…El ambiente interno de los centros de atención en salud constituye un hábitat natural para los microorganismos (bacteria, virus, hongos, parásitos), pudiendo ingresar éstos a través del aire que se introduce al abrir puertas y ventanas y así permanecer en las superficies y en el polvo 12 . Sin embargo, es reconocido, que la fuente más importante de microrganismos son las personas que ingresan a estos recintos, quienes los transportan, principalmente, en su piel y vías respiratorias 13 . Además, conociendo que el hombre inhala alrededor de 6-10 litros Infecciones Asociadas a la Atención de Salud Artículo de Investigación de aire por minuto, se hace necesario asegurar una buena calidad del aire, de tal forma de no afectar la salud de las personas que ingresan a esos recintos 13 .…”

“…Sin embargo, es reconocido, que la fuente más importante de microrganismos son las personas que ingresan a estos recintos, quienes los transportan, principalmente, en su piel y vías respiratorias 13 . Además, conociendo que el hombre inhala alrededor de 6-10 litros Infecciones Asociadas a la Atención de Salud Artículo de Investigación de aire por minuto, se hace necesario asegurar una buena calidad del aire, de tal forma de no afectar la salud de las personas que ingresan a esos recintos 13 . Así, la OMS ha publicado una serie de artículos enfocados en este tema, dando énfasis a que la calidad del aire, al interior de los recintos, es un aspecto cada vez más importante para la salud ocupacional y pública, puesto que afecta la salud de las personas, en especial aquellas más vulnerables, debido a su edad o estado de salud 1,2 .…”

“…Por otra parte, se ha descrito que la presencia de bacterias y hongos en el aire, al interior de recintos cerrados, está influenciada por distintos factores ambientales entre los que se encuentran la T, la HR, la ventilación y aire acondicionado, los niveles de dióxido de carbono, concentración de oxígeno, polvos antropogénicos, tipo y materiales de construcción 3,16 . Aunque, sin duda, en recintos cerrados no industriales, la fuente más importante de microorganismos en el aire es la presencia humana 13,15,16 . En este estudio no se encontró correlación significativa entre los factores ambientales de T, HR y el recuento microbiológico (P > 0,05).…”

Untitled

“…Air Filters -Air purifiers with high-efficiency particulate filters remove particulate matter as well as microorganisms in the indoor environment [41]. These are flat and pleated filters used to mechanically filter the airborne particles.…”