Airborne particles in indoor environment of homes, schools, offices and aged care facilities: The main routes of exposure

Abstract

It has been shown that the exposure to airborne particulate matter is one of the most significant environmental risks people face. Since indoor environment is where people spend the majority of time, in order to protect against this risk, the origin of the particles needs to be understood: do they come from indoor, outdoor sources or both? Further, this question needs to be answered separately for each of the PM mass/number size fractions, as they originate from different sources. Numerous studies have been conducted for specific indoor environments or under specific setting. Here our aim was to go beyond the specifics of individual studies, and to explore, based on pooled data from the literature, whether there are generalizable trends in routes of exposure at homes, schools and day cares, offices and aged care facilities. To do this, we quantified the overall 24h and occupancy weighted means of PM, PM and PN - particle number concentration. Based on this, we developed a summary of the indoor versus outdoor origin of indoor particles and compared the means to the WHO guidelines (for PM and PM) and to the typical levels reported for urban environments (PN). We showed that the main origins of particle metrics differ from one type of indoor environment to another. For homes, outdoor air is the main origin of PM and PM but PN originate from indoor sources; for schools and day cares, outdoor air is the source of PN while PM and PM have indoor sources; and for offices, outdoor air is the source of all three particle size fractions. While each individual building is different, leading to differences in exposure and ideally necessitating its own assessment (which is very rarely done), our findings point to the existence of generalizable trends for the main types of indoor environments where people spend time, and therefore to the type of prevention measures which need to be considered in general for these environments.

Airborne spread of expiratory droplet nuclei between the occupants of indoor environments: A review

“…This section is intended to review the general influence of factors on the airborne transmission indoors. However, it should be noted that different types of indoor environment (eg, residential buildings, office buildings, schools, hospitals, and aircraft cabins) could have very distinctive issues and characteristics of airborne transmission, basically because of their different geometries and layouts of indoor spaces, air distribution methods, supply flow rates, occupant densities, occupants’ behaviors, etc . For example, residential buildings do not have a fixed layout of occupants and they are mostly naturally ventilated when the outdoor air temperature is acceptable.…”

Exposure to ultrafine particles in children until 18 years of age: A systematic review

“…A recent literature review by Morawska et al has summed up the UFP levels measured outdoors and indoors in houses, offices, schools, and day‐care centers, measured by international studies. Only one recent literature review regarding child exposure was found .…”

“…Studies carried out in rural environments showed a higher indoor UFP concentration (Figure ). In the review by Morawska et al, in which the UFP exposure levels found in different studies were weighted and expressed as mean exposure levels, these were higher indoors than outdoors (1.44·10 4 and 1.31·10 4 part/cm 3 , respectively). This is probably due to the fact that in these environments there are fewer outdoor UFP sources compared with urban or suburban areas .…”

Indoor air pollution and exposure assessment of the gulf cooperation council countries: A critical review

“…Indoor air pollution is a serious health problem as it causes about 4.5 million annual deaths globally resulting from pneumonia (12%), stroke (34%), ischemic heart diseases (IHD) (26%), chronic obstructive pulmonary diseases (COPD) (22%), and lung cancer (LC) (6%) (Amoatey et al, 2017;Tageldin et al, 2012;Thurston et al, 2016;WHO, 2018). Indoor air pollution has been extensively studied in homes (Morawska et al, 2017;Rohra and Taneja, 2016), schools (Cai et al, 2015;Forns et al, 2017), hospitals (Cabo Verde et al, 2015;Wang et al, 2015b), offices (Azuma et al, 2018;Song et al, 2015), restaurants (Dai et al, 2018;Fazlzadeh et al, 2015), and subway metros (Kim et al, 2015;Xu and Hao, 2017). However, indoor air pollution continues to be a global problem, especially in developing countries.…”

“…These indoor air pollutants generally originate from the ambient environment. However, in cities with high ambient air pollutant levels, indoor air pollutants may be of greater concern (Morawska et al, 2017).…”