Exposure to PM2.5, Ultrafine and Black Carbon Particles in Green vs. Non-Green Homes

摘要

Environmental concerns for improved energy consumption are driving a green building/remodeling movement. Energy conservation efforts have resulted in tighter buildings, which have led to a reduction in the air exchange rates between indoor and outdoor environments. Poor air exchange rates could lead to an increase in particles that often originate from indoor sources (tobacco smoke, cooking), but decrease particles from outdoor sources (traffic, combustion). We assessed the concentration of particles alongside air exchange rates (AER) in 30 non-green and 27 green homes. Particles ≤ 2.5 μm (PM2.5) were sampled on 37 mm, 2.0 μm pore-size PTFE membrane filters using single-stage Personal Modular Impactors (SKC, Inc.) and analyzed gravimetrically. In addition, real-time number concentrations of ultrafine particles and mass concentrations of black carbon were assessed using a P-Trak condensation nuclei counter (TSI Inc.) and microAeth® monitors (AethLabs), respectively. Capillary adsorption tubes (CAT) and sources were placed in different locations of the homes to determine the AER. Information on home characteristics was collected by questionnaires. At baseline (immediately post renovation) the AER was significantly higher (p=0.02) in non-green homes (median=3.1 h-1) as compared to green homes (median=1.1 h-1). The geometric mean of PM2.5 was 80 μg.m-3 in green homes and 56 μg.m-3 in non-green homes (p=0.1) and the geometric mean of the number concentration of ultrafine particles was 26087 cm-3 in green homes and 32535 cm-3 in non-green homes (p=0.2). Preliminary data show a higher concentration of ultrafine particles in green homes at 6 months (p=0.05) and at 12 months (p=0.3). Black carbon, which was measured only at 12 months, showed an increasing trend (p=0.06) in non-green homes. Further data analysis will tease out the influence of human activity versus the renovation status of homes.