HVAC filtration for controlling infectious airborne disease transmission in indoor environments: Predicting risk reductions and operational costs

Azimi, Parham; Stephens, Brent

doi:10.1016/j.buildenv.2013.08.025

Cited by 152 publications

(154 citation statements)

References 58 publications

(52 reference statements)

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“…We assume that the low‐efficiency filters in home HAC systems are changed three times per year and, to be conservative, that the high‐efficiency filters are changed four times per year . For homes, the annual incremental cost per person of purchasing higher‐efficiency filters, CST P, is

{CST}_{normalP} = (4 P_{normalH} - 3 P_{normalL}) / O_{normalH}

…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Effectiveness and cost of reducing particle‐related mortality with particle filtration

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Chan

2017

Indoor Air

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This study evaluates the mortality-related benefits and costs of improvements in particle filtration in U.S. homes and commercial buildings based on models with empirical inputs. The models account for time spent in various environments as well as activity levels and associated breathing rates. The scenarios evaluated include improvements in filter efficiencies in both forced-air heating and cooling systems of homes and heating, ventilating, and air conditioning systems of workplaces as well as use of portable air cleaners in homes. The predicted reductions in mortality range from approximately 0.25 to 2.4 per 10 000 population. The largest reductions in mortality were from interventions with continuously operating portable air cleaners in homes because, given our scenarios, these portable air cleaners with HEPA filters most reduced particle exposures. For some interventions, predicted annual mortality-related economic benefits exceed $1000 per person. Economic benefits always exceed costs with benefit-to-cost ratios ranging from approximately 3.9 to 133. Restricting interventions to homes of the elderly further increases the mortality reductions per unit population and the benefit-to-cost ratios.

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{CST}_{normalP} = (4 P_{normalH} - 3 P_{normalL}) / O_{normalH}

…”

Section: Methodsmentioning

confidence: 99%

“…The estimated purchase prices of filters are based on data from Azimi and Stephens and data available via the Internet. For homes, we assume an average cost per filter of $4 for the MERV 6 filter and an average cost per filter of $9 for the MERV 12 filter.…”

Section: Model Inputsmentioning

confidence: 99%

Effectiveness and cost of reducing particle‐related mortality with particle filtration

Fisk

Chan

2017

Indoor Air

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“…Human pathogens that are known to be transmitted at least partially via the airborne route include a number of viral, bacterial, and fungal species. Among the known airborne transmitted viruses are those that cause measles, mumps, chicken pox, influenza, SARS, and the common cold . These include viruses with DNA genomes as well as both plus‐ and minus‐strand RNA genomes.…”

Section: Introductionmentioning

confidence: 99%

Quantifying the size-resolved dynamics of indoor bioaerosol transport and control

et al. 2017

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Understanding the bioaerosol dynamics of droplets and droplet nuclei emitted during respiratory activities is important for understanding how infectious diseases are transmitted and potentially controlled. To this end, we conducted experiments to quantify the size-resolved dynamics of indoor bioaerosol transport and control in an unoccupied apartment unit operating under four different HVAC particle filtration conditions. Two model organisms (Escherichia coli K12 and bacteriophage T4) were aerosolized under alternating low and high flow rates to roughly represent constant breathing and periodic coughing. Size-resolved aerosol sampling and settle plate swabbing were conducted in multiple locations. Samples were analyzed by DNA extraction and quantitative polymerase chain reaction (qPCR). DNA from both organisms was detected during all test conditions in all air samples up to 7 m away from the source, but decreased in magnitude with the distance from the source. A greater fraction of T4 DNA was recovered from the aerosol size fractions smaller than 1 μm than E. coli K12 at all air sampling locations. Higher efficiency HVAC filtration also reduced the amount of DNA recovered in air samples and on settle plates located 3-7 m from the source.

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“…Airborne transmitted pathogenic infections can cause various diseases and threaten human health and lives severely. Indoor pathogens can be transmitted through the heating, ventilating and air conditioning (HVAC) systems . To reduce infection risk, engineering control strategies should be implemented.…”

Section: Introductionmentioning

confidence: 99%

“…Medium‐grade filters—MERV ratings from 5 to 9, are not effective for removing small bacteria and viruses . For many general premises, it is not economically feasible to apply high ventilation rates or use high‐efficiency particulate air (HEPA) filters . Considering the adverse implication of exposure to indoor airborne pathogens on human health, there is a huge demand for efficient indoor air disinfection technologies …”

Section: Introductionmentioning

confidence: 99%

Comparison of disinfection performance of UVC‐LED and conventional upper‐room UVGI systems

2019

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We developed a novel, compact upper‐room ultraviolet germicidal irradiation system with light‐emitting diode sources (UR‐UVGI‐LED) to enhance the disinfection of bioaerosols in an enclosed room space. Its effectiveness was evaluated and compared with the conventional upper‐room ultraviolet germicidal irradiation system with mercury vapor sources (UR‐UVGI‐MV). Escherichia coli, Serratia marcescens, and Staphylococcus epidermidis were atomized under the well‐mixed condition and exposed to UR‐UVGI‐LED (or UR‐UVGI‐MV) device. The intensity output of the UR‐UVGI‐LED was also varied from 0% (no LED), 25%, 50% to 100% to further evaluate the UR‐UVGI‐LED disinfection effectiveness under different power levels. The decay rates for UR‐UVGI‐LED ranged from −0.1420 ± 0.04 min−1 to −0.3331 ± 0.07 min−1 for Escherichia coli, −0.1288 ± 0.01 min−1 to −0.3583 ± 0.02 min−1 for Serratia marcescens, and −0.0330 ± 0.01 min−1 to −0.0487 ± 0.01 min−1 for Staphylococcus epidermidis. It was noticed that the intensity level had a non‐linear influence on the UR‐UVGI‐LED’s performance. The decay rates achieved by the UR‐UVGI‐MV system were −0.3867 ± 0.08 min−1, −0.4745 ± 0.002 min−1, and −0.1624 ± 0.02 min−1 for Escherichia coli, Serratia marcescens, and Staphylococcus epidermidis, respectively. Hence, the disinfection performance of both UR‐UVGI‐LED and UR‐UVGI‐MV systems was comparable for Escherichia coli and Serratia marcescens. These results demonstrate that the UR‐UVGI‐LED system has a high potential to be used as a safe and effective irradiated light source to disinfect indoor airborne pathogens.

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HVAC filtration for controlling infectious airborne disease transmission in indoor environments: Predicting risk reductions and operational costs

Cited by 152 publications

References 58 publications

Effectiveness and cost of reducing particle‐related mortality with particle filtration

Effectiveness and cost of reducing particle‐related mortality with particle filtration

Quantifying the size-resolved dynamics of indoor bioaerosol transport and control

Comparison of disinfection performance of UVC‐LED and conventional upper‐room UVGI systems

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