Room ventilation and the risk of airborne infection transmission in 3 health care settings within a large teaching hospital

Knibbs, Luke D.; Morawska, Lidia; Bell, Scott C.; Grzybowski, Piotr

doi:10.1016/j.ajic.2011.02.014

Cited by 94 publications

(70 citation statements)

References 24 publications

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“…These results were found at locations both directly in front of the coughing simulator and away from the initial cough aerosol plume, suggesting that exposure to the cough aerosol would occur anywhere in the room. This is consistent with modeling results reported by Knibbs et al, (28) although they and other authors also found that the configuration and direction of the ventilation system, and other factors, can have a large impact on exposure and that these factors are difficult to predict and control. (17,29,30) In a similar manner to the time scale discussion above, our results show that ventilation has a much greater effect on exposure over the long term than in the short period immediately after a cough.…”

Section: Discussionsupporting

confidence: 82%

Dispersion and Exposure to a Cough-Generated Aerosol in a Simulated Medical Examination Room

Lindsley

King

Thewlis

et al. 2012

Journal of Occupational and Environmental Hygiene

102

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Few studies have quantified the dispersion of potentially infectious bioaerosols produced by patients in the health care environment and the exposure of health care workers to these particles. Controlled studies are needed to assess the spread of bioaerosols and the efficacy of different types of respiratory personal protective equipment (PPE) in preventing airborne disease transmission. An environmental chamber was equipped to simulate a patient coughing aerosol particles into a medical examination room, and a health care worker breathing while exposed to these particles. The system has three main parts: (1) a coughing simulator that expels an aerosol-laden cough through a head form; (2) a breathing simulator with a second head form that can be fitted with respiratory PPE; and (3) aerosol particle counters to measure concentrations inside and outside the PPE and at locations throughout the room. Dispersion of aerosol particles with optical diameters from 0.3 to 7.5 μm was evaluated along with the influence of breathing rate, room ventilation, and the locations of the coughing and breathing simulators. Penetration of cough aerosol particles through nine models of surgical masks and respirators placed on the breathing simulator was measured at 32 and 85 L/min flow rates and compared with the results from a standard filter tester. Results show that cough-generated aerosol particles spread rapidly throughout the room, and that within 5 min, a worker anywhere in the room would be exposed to potentially hazardous aerosols. Aerosol exposure is highest with no personal protective equipment, followed by surgical masks, and the least exposure is seen with N95 FFRs. These differences are seen regardless of breathing rate and relative position of the coughing and breathing simulators. These results provide a better understanding of the exposure of workers to cough aerosols from patients and of the relative efficacy of different types of respiratory PPE, and they will assist investigators in providing research-based recommendations for effective respiratory protection strategies in health care settings.

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Section: Discussionsupporting

confidence: 82%

Dispersion and Exposure to a Cough-Generated Aerosol in a Simulated Medical Examination Room

Lindsley

King

Thewlis

et al. 2012

Journal of Occupational and Environmental Hygiene

102

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“…Among indoor environments where bioaerosols are considered a problem, hospitals are of major concern as in these environments there are a wide range of people such as hospital and medical staff, service users, patients and visitors who can contact bioaerosols and inhale them (11,12). Therefore, the presence of excess bioaerosol in hospitals air can be a serious health threat (13). Perdelli et al (14) studied fungi load in different wards of a hospital.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Bioaerosols in Five Educational Hospitals Wards Air in Hamedan, During 2011-2012

Hoseinzadeh

Samarghandie

Ghiasian

et al. 2013

Jundishapur J Microbiol

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Background: Some human diseases such as tuberculosis, Legionnaires' disease and different forms of bacterial pneumonia, coccidioidomycosis, influenza, measles, and gastrointestinal illnesses are the result of exposure to bioaerosols. In addition, they are associated with some noninfectious airway diseases, such as allergies and asthma. Objectives: In the education hospitals of Hamedan University of medical sciences, there were no previous qualitative and quantitative studies of bioaerosols in the air of wards, so in this study the quality and quantity of bioaerosols in hospital ward's air was investigated to establish a reference for future studies or measures. Materials and Methods:In this cross sectional research, 30 wards in five educational hospitals of Hamadan city were studied. More than 180 air samples were collected from the hospitals. The samples were transferred to blood agar and Sabouraud medium and cultivated immediately. Type and number of colonies were determined in the laboratory. Bioaerosol concentrations were calculated in terms of cfu/ m 3 . After bioaerosols isolation, the isolates were identified by morphology of colony, Gram staining and by standard biochemical tests as required for bacterial or fungal bioaerosols. The SPSS software was used for data management. ANOVA and t-test statistical analyses were also used. Results:As the results demonstrated, highest and lowest averages of bioaerosol density were obtained from Shahid Beheshti and Fatemieh Hospitals (36.18 cfu/m 3 Vs. 24.03 cfu/m 3 ), respectively. Highest and lowest concentrations of bioaerosols were found in Women1 and operating room wards of Fatemiyeh Hospital, respectively (54.4cfu/m 3 VS. 13.3cfu/m 3 ). It appears that there had been no significant correlation between concentration of bioaerosols in the hospitals and available guideline values (P = 0.3). The highest fungal populations were Penicelium spp. (32.06%), Cladosporium spp. (20.5%), Aspergillus fumigatus (14.61%) and A. niger (7.43%), respectively. The highest bacterial population was coagulase-negative staphylococci (32.49%), Bacillus spp. (14.74%), Micrococcus spp. (13.68%) and Staphylococcus aureus (11.34%), respectively. Conclusions: Quantitative bioaerosols concentration in the air of some hospitals was more than the available guideline i.e. 30 cfu/m 3 . Bioaerosol density of all surveyed hospitals can relate to patients presence in wards and their visitors, incorrect ventilation, and probably inefficient disinfection. Most surveyed hospitals have no air treatment systems thus to reduce bioaerosol concentration, standard ventilation systems should designed and utilized.

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“…Studies conducted under full scale conditions [12][13][14][15], within laboratory test facilities [16][17][18] and more recently through computational simulation [19][20][21][22][23][24][25][26][27] have all improved the understanding of infection risk which is directly influencing building design and ventilation guidance.…”

Section: Introductionmentioning

confidence: 99%

Measurement of ventilation and airborne infection risk in large naturally ventilated hospital wards

Gilkeson

Camargo‐Valero

Pickin

et al. 2013

Building and Environment

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Room ventilation and the risk of airborne infection transmission in 3 health care settings within a large teaching hospital

Abstract: Given the absence of definitive ventilation guidelines for hospitals, air-exchange measurements combined with modeling afford a useful means of assessing, on a case-by-case basis, the suitability of room ventilation for preventing airborne disease transmission.

Cited by 94 publications

References 24 publications

Dispersion and Exposure to a Cough-Generated Aerosol in a Simulated Medical Examination Room

Dispersion and Exposure to a Cough-Generated Aerosol in a Simulated Medical Examination Room

Evaluation of Bioaerosols in Five Educational Hospitals Wards Air in Hamedan, During 2011-2012

Measurement of ventilation and airborne infection risk in large naturally ventilated hospital wards

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