A Comparison between Temperature-Controlled Laminar Airflow Device and a Room Air-Cleaner in Reducing Exposure to Particles While Asleep

People spend approximately one third of their life sleeping. Exposure to pollutants in the
sleep environment often leads to a variety of adverse health effects, such as development
and exacerbation of asthma. Avoiding exposure to these pollutants by providing a sufficient
air quality in the sleep environment might be a feasible method to alleviate these health
symptoms.
We performed full-scale laboratory measurements using a thermal manikin positioned on
an experimental bed. Three ventilation settings were tested: with no filtration system operated,
use of portable air cleaner and use of a temperature-controlled laminar airflow (TLA)
device. The first part of the experiment investigated the air-flow characteristics in the breathing
zone. In the second part, particle removal efficiency was estimated. Measured in the
breathing zone, the room air cleaner demonstrated high turbulence intensity, high velocity
and turbulence diffusivity level, with a particle reduction rate of 52% compared to baseline
after 30 minutes. The TLA device delivered a laminar airflow to the breathing zone with a
reduction rate of 99.5%. During a periodical duvet lifting mimicking a subject's movement in
bed, the particle concentration was significantly lower with the TLA device compared to the
room air cleaner. The TLA device provided a barrier which significantly reduced the introduction
of airborne particles into the breathing zone. Further studies should be conducted for
the understanding of the transport of resuspended particles between the duvet and the laying body.