Indoor particle dynamics and cognitive performance of occupants in sleeping environments
Chai, Ming Sheng
Date of Issue2015
School of Civil and Environmental Engineering
As people tend to spend most of their time indoors, indoor particle exposures possibly constitute a significant portion of the overall exposure to these harmful particulate matter (PM). Singaporeans spend an average of 6.5 hours sleeping, which takes up more than one quarter of their lifetime. Therefore, there is a need to measure the indoor air quality (IAQ) of sleeping environments and determine their indoor environmental status. During the conduct of objective assessment, sampling data i.e. PM concentrations and other physical parameters, were collected in four test bedrooms under air-conditioned (AC) and natural ventilation (NV), with fan-assisted conditions. The data were compared with IAQ guidelines under Singapore Ministry of Environment. Generally, the ratios of indoor and outdoor (I/O ratios) particle concentrations in all test bedrooms were less than one under both conditions, with smaller ratios shown in AC condition than in NV condition for both fine and coarse particles. The result seems to show a trend of particle deposition loss-rate coefficient, KD in relative to the air exchange rate. The particle penetration factor, P for both fine and coarse particles were one or close to unity for most of the test sites. As for air-conditioner particle removal efficiency, KAC, the value tends to be greater for particles that were larger in size. Some of the values calculated in this study could be overestimated or underestimated due to the assumptions made of the absence of indoor particle emission and additional particle dynamic processes e.g. resuspension, coagulation of particles used in the model. In subjective assessment, the cognitive performance of occupants seems to show a trend relative to each of their preferred sleeping habit i.e. occupants tend to perform better when they slept in their preferred sleeping environment. The sample size of cognitive test was expanded and the results indicate that most participants showed an improvement in their cognitive tests, which include reaction test (Test 1), memory focus test (Test 2) and visual perception and cognitive skill test (Test 3), after their sleep in both conditions, with an exception of Test 3 under AC condition.
Final Year Project (FYP)
Nanyang Technological University