An assessment of Outpatient Clinic Room Ventilation Systems and Possible Relationship to Disease Transmission

BACKGROUND: With healthcare shifting to the outpatient setting, this study examined whether outpatient clinics operating in business occupancy settings were conducting procedures in rooms with ventilation rates above, at, or below thresholds defined in the American National Standards Institute/American Society of Heating, Refrigerating and Air-Conditioning Engineers/American Society for Health Care Engineering Standard 170 for Ventilation in Health Care Facilities and whether lower ventilation rates and building characteristics increase the risk of disease transmission. METHODS: Ventilation rates were measured in 105 outpatient clinic rooms categorized by services rendered. Building characteristics were evaluated as determinants of ventilation rates, and risk of disease transmission was estimated using the Gammaitoni-Nucci model. RESULTS: When compared to Standard 170, 10% of clinic rooms assessed did not meet the minimum requirement for general exam rooms, 39% did not meet the requirement for treatment rooms, 83% did not meet the requirement for aerosol-generating procedures, and 88% did not meet the requirement for procedure rooms or minor surgical procedures. CONCLUSIONS: Lower than standard air changes per hour were observed and could lead to an increased risk of spread of diseases when conducting advanced procedures and evaluating persons of interest for emerging infectious diseases. These findings are pertinent during the SARS-CoV-2 pandemic, as working guidelines are established for the healthcare community

Inbuilt potential of YEM medium and its constituents to generate Ag/Ag₂O nanoparticles.

We discovered that Yeast Extract Mannitol (YEM) medium possessed immense potential to generate silver nanoparticles from AgNO3 upon autoclaving, which was evident from (i) alteration in color of the medium; (ii) peak at ∼410 nm in UV-Vis spectrum due to surface plasmon resonance specific to silver nanoparticles; and (iii) TEM investigations. TEM coupled with EDX confirmed that distinct nanoparticles were composed of silver. Yeast extract and mannitol were key components of YEM medium responsible for the formation of nanoparticles. PXRD analysis indicated crystalline geometry and Ag/Ag2O phases in nanoparticles generated with YEM medium, yeast extract and mannitol. Our investigations also revealed that both mannitol and yeast extract possessed potential to convert ∼80% of silver ions in 0.5 mM AgNO3 to nanoparticles, on autoclaving for 30 min at 121°C under a pressure of 1.06 kg/cm(2). Addition of filter sterilized AgNO3 under ambient conditions to pre-autoclaved YEM medium and yeast extract brought about color change due to the formation of silver nanoparticles, but required prolonged duration. In general, even after 72 h intensity of color was significantly less than that recorded following autoclaving. Silver nanoparticles formed at room temperature were more heterogeneous compared to that obtained upon autoclaving. In summary, our findings demonstrated that (i) YEM medium and its constituents promote synthesis of silver nanoparticles; and (ii) autoclaving enhances rapid synthesis of silver nanoparticles by YEM medium, yeast extract and mannitol

Evaluation of silver nanoparticles formed by incubating filter-sterilized AgNO₃ with pre-autoclaved yeast extract (YE) under ambient conditions.

<p><b>a</b>: Alteration in color of YE with 0, 0.1, 0.25 and 0.5 mM AgNO₃ after 72 h. <b>b</b>: UV-Vis absorption spectra of YE incubated with 0, 0.1, 0.25 and 0.5 mM AgNO₃ for 72 h. <b>c</b>: TEM images of silver nanoparticles formed under ambient conditions.</p

Characterization of silver nanoparticles formed by autoclaving AgNO₃ with mannitol and yeast extract (YE).

<p><b>a–b</b>: TEM images of silver nanoparticles synthesized with 53 mM Mannitol. <b>c–d</b>: TEM images of silver nanoparticles synthesized with 0.1% YE. <b>e–f</b>: EDX spectra of nanoparticles formed with mannitol and YE, respectively, showing the peaks for Ag, indicating nanoparticles to be composed of silver. Other prominent peaks of C and Cu, noted in the figure are due to the carbon coated copper grids. <b>Inset e–f</b>: SAED pattern of the silver nanoparticles formed with mannitol and YE, respectively, showing the crystalline nature of the nanoparticles.</p

Evaluation of silver nanoparticles formed by autoclaving AgNO₃ with yeast extract (YE) and mannitol.

<p><b>a</b>: Alteration in color of 0.1, 0.25 and 0.5 mM AgNO₃ autoclaved with 53 mM mannitol and 0.1% yeast extract. <b>b–c</b>: UV-Vis absorption spectra of 0.1, 0.25 and 0.5 mM AgNO₃ after autoclaving with 53 mM mannitol and 0.1% yeast extract, respectively.</p

Evaluation of contribution of YEM medium components for silver nanoparticles generation upon autoclaving with AgNO₃.

<p><b>a</b>: Alteration in color of 0.25 mM AgNO₃ upon autoclaving with different components of YEM medium namely, yeast extract (YE), mannitol, MgSO4, NaCl and K2HPO4 medium individually. <b>b</b>: UV-Vis absorption spectra of 0.25 mM AgNO₃ after autoclaving with YEM medium, yeast extract, mannitol, MgSO4, NaCl and K2HPO4.</p

Evaluation of silver nanoparticles formed by incubating filter-sterilized AgNO₃ with pre-autoclaved YEM medium under ambient conditions.

<p><b>a–b</b>: Alteration in color of YEM medium incubated in presence of 0, 0.1, 0.25 and 0.5 mM AgNO₃ after ∼8 h (a) and 72 h (b). <b>c</b>: UV-Vis absorption spectra of 0, 0.1, 0.25 and 0.5 mM AgNO₃ incubated with YEM medium for 72 h. <b>d</b>: TEM image of silver nanoparticles formed under ambient conditions.</p