Concentrations and Sources of Airborne Particles in a NICU

Hello everyone! I’d like to draw your attention to our just published year-long study focusing on little investigated topic titled: “Concentrations and sources of airborne particles in a neonatal intensive care unit”. The main outcomes of the study are the following:

  • The contribution of outdoor particles to indoor particle mass concentrations was particularly low owing to the effectiveness of the ventilation system including HEPA filtration. Although the mass concentration of particles from outdoor air was small, the contribution of ventilation to small particles as assessed by total particle number concentration was highly sensitive to the influence of outdoor air, which highlights the importance of maintaining efficient particle filtration and limiting air infiltration through the building envelope.
  • This work has also demonstrated a strong temporal and spatial association between the indoor particle mass concentration and human occupancy, both considering the temporal pattern in the hospital overall and focusing on infant rooms in particular. The detected particle peaks tied to occupancy were substantially more discernible among larger particles, as would be expected for shedding and resuspension. Conversely, room occupancy contributed little to submicron particle generation.
  • Within-room emissions made the highest relative source contribution to baby room coarse particle concentrations. Near-room emissions also contributed substantially to baby room coarse particle loads, especially in relation to the small contribution from outdoor air, indicating a possibility to reduce infants’ exposure by further isolating the air in their room from nearby air outside the room.
  • That the occupancy-associated emissions within the room are dominant contributors to airborne particulate concentrations in NICU environments suggests that they may also be an environmental factor influencing infant health. Further evidence supporting this view emerged from our pilot study, revealing that the particle concentrations inside an infant incubator were a substantial proportion of those in room air.
  • Emerging evidence supports a view that occupancy is an important source of indoor airborne bacteria and fungi. It seems worthwhile to consider whether improved nosocomial infection control can be achieved by further limiting bioaerosol emissions associated with occupancy.

It’s also worth noting we have amassed several thousand swab and wipe samples from around this NICU. While the data is still being generated, early results point to an environment largely dominated by skin associated microorganisms. In tracking biomass across time, our data echoes that of the indoor “wasteland” recently reported, but we do find some reservoirs of active growth. More details on microbes in the NICU will be presented during an oral presentation in a couple of weeks at the Sloan MoBE conference in Boulder.

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