AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Real-time, Size-Resolved Particle Concentrations in a Neonatal Intensive Care Unit
SEEMA BHANGAR, Brandon Brooks, Fuqun Vasiknanonte, Xiaochen Tang, Jillian Banfield, William Nazaroff, University of California, Berkeley
Abstract Number: 706 Working Group: Indoor Aerosols
Abstract Infants in neonatal intensive care units (NICU) are particularly vulnerable to environmental stress including air pollution. However, few studies have reported particle levels in the NICU environment. During a four-day investigation in a private-style NICU, we measured size-resolved particle number concentrations at 1-min resolution. The investigation was conducted in an empty patient room in an otherwise normally functioning NICU, to enable the measurement of parameters inside and outside the incubator, and to observe changes in response to simulated human activities. Internal doors between the room and hallway were open to mimic typical conditions. The NICU air handling system included high-efficiency particle filters.
Preliminary results show background PN levels in the room were 1-2 orders of magnitude lower than outdoors. Four-day (87 h) mean concentrations corresponding to the 6 particle size ranges (0.3-0.5, 0.5-1, 1-2, 2-5, 5-10, >10 micro-meter) were 45, 17, 7.7, 9.2, 2.0, and 2.2 L$^(-1), respectively. Levels inside the incubator were further reduced owing to the presence of a filter in the incubator air inlet. Incubator/room PN concentration ratios ranged from 0.7 to 0.1 across the size ranges evaluated, except when the internal humidifier – which was a source of particles – was in operation. The air-exchange rate of the humidifier was approximately 9 h$^(-1).
The presence and activities of occupants were associated with distinct particle peaks across all measured size ranges. The highest levels were observed when fabrics were handled. However, against the low background, even small perturbations – such as from a person entering and sitting in the room for a few minutes – were discernible. The data are being further analyzed to evaluate the fraction of the total particle signal attributable to occupancy. We are also exploring the use of a material-balance model to estimate human emissions as a function of particle size and the type of activity.