Experimental and Numerical Analysis of the Relationship Between Indoor and Outdoor Airborne Particles in an Operating Room

Abstract

This work investigated the impact of the HVAC filtration system and indoor particle sources on the relationship between indoor and outdoor airborne particle size and concentrations in an operating room. Filters with efficiency between 65% and 99.97% were used in the investigation and indoor and outdoor particle size and concentrations were measured. A balance mass model was used for the simulation of the impact of the surgical team, deposition rate, HVAC exhaust and air change rates on indoor particle concentration. The experimental results showed that high efficiency filters would not be expected to decrease the risk associated with indoor particles larger than approximately 1 mm in size because normal filters are relatively efficient for these large particles. A good fraction of outdoor particles were removed by deposition on the HVAC system surfaces and this deposition increased with particle size. For particles of 0.3-0.5 mm in diameter, particle reduction was about 23%, while for particles 410 mm the loss was about 78%. The modelling results showed that depending on the type of filter used, the surgical team generated between 93% and 99% of total particles, while the outdoor air contributed only 1-6%.

Sources and dynamics of fluorescent particles in hospitals

“…The perturbation and movement of textiles (linen, gowns, bandages, blankets, etc.) are an important source of the airborne particle in operating rooms . Recent findings were reported by Handorean et al .…”

“…43 However, although this interference may occur, it is important to understand and consider the influence of bed making on the generation of particles in hospitals, as there were studies that correlated bioaerosols generated in hospital with the perturbations and movement of contaminated textiles. 4,14,16,17,24,44 A recent study by Dai et al 7 in operating rooms using fluorescent particle counters supports this concern and found a significant correlation between fluorescent particle counts and bacterial counts. The perturbation and movement of textiles (linen, gowns, bandages, blankets, etc.)…”

“…This finding must be viewed with caution, because some materials that can influence strongly the generation of florescence particles, for example, bleached cotton fibers . However, although this interference may occur, it is important to understand and consider the influence of bed making on the generation of particles in hospitals, as there were studies that correlated bioaerosols generated in hospital with the perturbations and movement of contaminated textiles . A recent study by Dai et al .…”

“…Given this diversity of sources, regular environmental surveys and suitable control measures are necessary to help to reduce hospital‐acquired infections . Despite the importance of good environmental hygiene in hospitals, few experimental studies have focused on air quality there and the existing information on this topic is limited …”

“…3 Despite the importance of good environmental hygiene in hospitals, few experimental studies have focused on air quality there and the existing information on this topic is limited. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Of particular significance in hospitals are bioaerosols, which are airborne particles of biological origin and include microorganisms, as well as their metabolites, toxins, or fragments. 19,20 Information about the relative contribution of different sources to indoor bioaerosol levels is very limited, despite their potential health impacts.…”