Effects of air cleaners and school characteristics on classroom concentrations of particulate matter in 34 elementary schools in Korea

Park, Ju‐Hyeong; Lee, Tae Jung; Park, Ju Hee; Oh, Hyung Na; Jo, Young Min

doi:10.1016/j.buildenv.2019.106437

Cited by 60 publications

(38 citation statements)

References 26 publications

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“…Our measurements as well as previous studies (e.g., Polidori et al, 2013;Chen et al, 2015;Park et al, 2020) demonstrate that operating air purifiers continuously in a closed room also reduces the amount of particulate matter (PM2.5 and PM10) considerably. The WHO recommends that the average exposure levels to PM 2.5 should be below 10 µg/m 3 because higher exposure increases the risks of ischaemic heart disease, chronic obstructive pulmonary disease, lung cancer, cerebrovascular disease leading to stroke, and various other diseases.…”

Section: Co-benefitssupporting

confidence: 89%

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Testing mobile air purifiers in a school classroom: Reducing the airborne transmission risk for SARS-CoV-2

Curtius

Granzin

Schrod

2020

Preprint

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Airborne transmission of SARS-CoV-2 through virus-containing aerosol particles has been established as an important pathway for Covid-19 infection. Suitable measures to prevent such infections are imperative, especially in situations when a high number of persons convene in closed rooms. Here we tested the efficiency and practicability of operating four air purifiers equipped with HEPA filters in a high school classroom while regular classes were taking place. We monitored the aerosol number concentration for particles > 3 nm at two locations in the room, the aerosol size distribution in the range from 10 nm to 10 μm, PM10 and CO2 concentration. For comparison, we performed similar measurements in a neighboring classroom without purifiers. In times when classes were conducted with windows and door closed, the aerosol concentration was reduced by more than 90 % within less than 30 minutes when running the purifiers (air exchange rate 5.5 h-1). The reduction was homogeneous throughout the room and for all particle sizes. The measurements are supplemented by a calculation estimating the maximum concentration levels of virus-containing aerosol from a highly contagious person speaking in a closed room with and without air purifiers. Measurements and calculation demonstrate that air purifiers represent a well suited measure to reduce the risks of airborne transmission of SARS-CoV-2 substantially. Staying for two hours in a closed room with a super infective person, we estimate that the inhaled dose is reduced by a factor of six when using air purifiers with a total air exchange rate of 5.7 h-1.

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Section: Co-benefitssupporting

confidence: 89%

“…A few studies have tested air purifiers in classrooms, e.g. as a measure to reduce exposure to PM for children with asthma (Jhun et al, 2018), , the efficiency to remove ultrafine particles, black carbon, PM 2.5 and PM 10 was tested (Polidori et al, 2013), or PM2.5 and PM10 alone (Park et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Testing mobile air purifiers in a school classroom: Reducing the airborne transmission risk for SARS-CoV-2

Curtius

Granzin

Schrod

2020

Preprint

View full text Add to dashboard Cite

show abstract

“…Our measurements as well as previous studies (e.g., Chen et al 2015;Park et al 2020;Polidori et al 2013) demonstrate that operating air purifiers continuously in a closed room also reduces the amount of particulate matter (PM 2.5 and PM 10 ) considerably. The WHO recommends that the average exposure levels to PM 2.5 should be below 10 µg/m 3 because higher exposure increases the risks of ischaemic heart disease, chronic obstructive pulmonary disease, lung cancer, cerebrovascular disease leading to stroke, and various other diseases.…”

Section: Co-benefitssupporting

confidence: 88%

Testing mobile air purifiers in a school classroom: Reducing the airborne transmission risk for SARS-CoV-2

Curtius

Granzin

Schrod

2021

Aerosol Science and Technology

147

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Airborne transmission of SARS-CoV-2 through virus-containing aerosol particles has been established as an important pathway for Covid-19 infection. Suitable measures to prevent such infections are imperative, especially in situations when a high number of persons convene in closed rooms. Here we tested the efficiency and practicability of operating four air purifiers equipped with HEPA filters in a high school classroom while regular classes were taking place. We monitored the aerosol number concentration for particles > 3 nm at two locations in the room, the aerosol size distribution in the range from 10 nm to 10 µm, PM 10 and CO 2 concentration. For comparison, we performed similar measurements in a neighboring classroom without purifiers. In times when classes were conducted with windows and door closed, the aerosol concentration was reduced by more than 90 % within less than 30 minutes when running the purifiers (air exchange rate 5.5 h-1). The reduction was homogeneous throughout the room and for all particle sizes. The measurements are supplemented by a calculation estimating the maximum concentration levels of virus-containing aerosol from a highly contagious person speaking in a closed room with and without air purifiers. Measurements and calculation demonstrate that air purifiers potentially represent a well-suited measure to reduce the risks of airborne transmission of SARS-CoV-2 substantially. Staying for two hours in a closed room with a highly infective person, we estimate that the inhaled dose is reduced by a factor of six when using air purifiers with a total air exchange rate of 5.7 h-1 .

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“…Filter-type air purifiers are used to control indoor fine particulate matter in South Korea, and there has been a broad range of studies on air purifiers and fine particulate matter. However, previous studies focused on the purification effects caused by the airflow rate and filter grade of air purifiers and have not evaluated the operating method of air purifiers that considers the inflow path of fine particulate matter into the body and the breathing zone of occupants or the performance in reducing the concentration of particulate matter [11][12][13][14][15][16][17][18][19]. As various sources cause indoor fine particulate matter [20], operating a fixed air purifier can reduce the average concentration of indoor fine particulate matter, but the reduction effect against fine particulate matter in local areas such as the breathing zone of occupants is inadequate.…”

Section: Introductionmentioning

confidence: 99%

Evaluation on Air Purifier’s Performance in Reducing the Concentration of Fine Particulate Matter for Occupants according to its Operation Methods

Park

Seo

2020

IJERPH

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Fine particulate matter entering the body through breathing cause serious damage to humans. In South Korea, filter-type air purifiers are used to eliminate indoor fine particulate matter, and there has been a broad range of studies on the spread of fine particulate matter and air purifiers. However, earlier studies have not evaluated an operating method of air purifiers considering the inflow of fine particulate matter into the body or reduction performance of the concentration of fine particulate matter. There is a limit to controlling the concentration of fine particulate matter of the overall space where an air purifier is fixed in one spot as the source of indoor fine particulate matter is varied. Accordingly, this study analyzed changes in the concentration of indoor fine particulate matter through an experiment according to the discharging method and location of a fixed air purifier considering the inflow route of fine particulate matter into the body and their harmfulness. The study evaluated the purifiers’ performance in reducing the concentration of fine particulate matter in the occupants’ breathing zone according to the operation method in which a movable air purifier responds to the movement of occupants. The results showed the concentration of fine particulate matter around the breathing zone of the occupants had decreased by about 51 μg/m3 compared to the surrounding concentration in terms of the operating method in which an air purifier tracks occupants in real-time, and a decrease of about 68 μg/m3 in terms of the operating method in which an air purifier controls the zone. On the other hand, a real-time occupant tracking method may face a threshold due to the moving path of an air purifier and changes in the number of occupants. A zone controlling method is deemed suitable as an operating method of a movable air purifier to reduce the concentration of fine particulate matter in the breathing zone of occupants.

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Effects of air cleaners and school characteristics on classroom concentrations of particulate matter in 34 elementary schools in Korea

Cited by 60 publications

References 26 publications

Testing mobile air purifiers in a school classroom: Reducing the airborne transmission risk for SARS-CoV-2

Testing mobile air purifiers in a school classroom: Reducing the airborne transmission risk for SARS-CoV-2

Testing mobile air purifiers in a school classroom: Reducing the airborne transmission risk for SARS-CoV-2

Evaluation on Air Purifier’s Performance in Reducing the Concentration of Fine Particulate Matter for Occupants according to its Operation Methods

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