[show abstract][hide abstract] ABSTRACT: In this study, the impact factors of temperature, relative humidity (RH), air exchange rate, and volatile organic compound (VOC) properties on the VOC (toluene, n-butyl acetate, ethylbenzene, and m,p-xylene) specific emission rates (SERs) and concentrations from wooden flooring were investigated by chamber test for 8 days. The tested wood in this study is not common solid wood, but composite wood made of combined wood fibers. The experiments were conducted in a stainless-steel environmental test chamber coated with Teflon. The experimental results within 8 days of testing showed that, when the temperature increased from 15 to 30 °C, the VOC SERs and concentrations increased 1.5–129 times. When the RH increased from 50% to 80%, the VOC concentrations and SERs increased 1–32 times. When the air change rate increased from 1 to 2 h−1, the VOC concentrations decreased 9–40%, while the VOC SERs increased 6–98%. The relations between the boiling points of the VOCs and each of the normalized VOC SERs and concentrations were linear with negative slopes. The relations between the vapor pressures of the VOCs and each of the normalized VOC SERs and concentrations were linear with positive slopes. At 15 °C, RH50%, the relations between the diffusivities of VOCs and each of the normalized VOC equilibrium SERs and concentrations were linear with a positive slope.
Building and Environment 02/2013; · 2.43 Impact Factor
[show abstract][hide abstract] ABSTRACT: In this study, we investigated the effect of relative humidity (RH) on the formation of secondary organic aerosol (SOA) generated from the ozonolysis of d-limonene in an environmental chamber. The mass yield and the number concentration of SOA increased seven and eight times, respectively, when the RH increased from 18% to 82%. The measured total loss rates (apparent loss rates) of the number and mass concentration of SOA in the chamber ranged from 1.70 to 1.77 h(-1) and from 2.51 to 2.61 h(-1), respectively, at a controlled ventilation rate of 0.72±0.04 h(-1). The wall-deposition-loss-rate coefficient observed (1.00±0.02 h(-1)) was approximate to the estimated value based on Zhao and Wu's model which includes the factors of turbulence, Brownian diffusion, turbophoresis and surface roughness. According to the ICRP (International Commission on Radiological Protection) model, the inhaled SOA particles are deposited primarily in the alveoli of the lung. The integrated alveolar deposited dose of the mass (surface area) of SOA over 3h accounted for 74.0-74.8% (74.3-74.9%) of the total deposited dose at the investigated RH. Raising the RH resulted in the growth of SOA particle sizes and increment of the deposition dose but did not cause significant changes in the ratio of regional to the total respiratory deposition of SOA.
Journal of hazardous materials 07/2011; 191(1-3):94-102. · 4.14 Impact Factor
[show abstract][hide abstract] ABSTRACT: To examine the inhalation exposure of cooks at night markets in Taiwan to PAHs and to estimate the corresponding potential human health risks posed by the inhalation of carcinogenic PAHs.
Eight-hour personal air samples collecting particle-bound PAHs and XAD-2 retaining PAHs in the gas phase were taken by personal PM(2.5) cyclones with cooks carrying the sampler on the shoulder while cooking at selected food stalls at four night markets in Taipei, and the concentrations of 16 priority PAHs in both particulates and air were measured with GC/MS.
The total identified PAHs in both gas and PM(2.5) phases exposed by cooks during cook hours ranged from 233,995 to 44,166 ng m(-3). Total exposed PAHs in cooks, as well as the percentage of PAHs in PM(2.5), were the highest at the barbecue stall F3. The fractions of gaseous PAHs (97%) in the four food stalls were consistently higher than the fractions of particulate PAHs (3%). The diagnostic ratios of PAHs fell within the range of those found in other studies related to cooking. At all typical food stalls in night markets except for F2, the excess lifetime cancer risk (ELCR) of cooks are beyond the acceptable target risk range of 10(-6) to 10(-4) for occupational workers set by USEPA.
The PAHs measured in the night markets originated from combustion due to food cooking. The control of gaseous PAH emissions would be more important than the fractions of particulate PAH emissions. Occupational exposure to cooking emissions in Taiwanese workers at night markets is of health concern. Thus, effective protective measures are therefore suggested to minimize cooks' exposure to such emissions, such as wearing mask of activated carbon, evacuating the exhaust into water tank with bio-surfactant to improve PAH removal, installing effective mechanical exhaust vacuum or building high exhaust fume hood above cooking ovens.
International Archives of Occupational and Environmental Health 03/2011; 84(3):231-7. · 2.10 Impact Factor
[show abstract][hide abstract] ABSTRACT: In Taiwan, there are more than 300 night markets and they have attracted more and more visitors in recent years. Air quality in night markets has become a public concern. To characterize the current air quality in night markets, four major night markets in Kaohsiung were selected for this study. The results of this study showed that the mean carbon dioxide (CO2) concentrations at fixed and moving sites in night markets ranged from 326 to 427 parts per million (ppm) during non-open hours and from 433 to 916 ppm during open hours. The average carbon monoxide (CO) concentrations at fixed and moving sites in night markets ranged from 0.2 to 2.8 ppm during non-open hours and from 2.1 to 14.1 ppm during open hours. The average 1-hr levels of particulate matter with aerodynamic diameters less than 10 microm (PM10) and less than 2.5 microm (PM2.5) at fixed and moving sites in night markets were high, ranging from 186 to 451 microg/m3 and from 175 to 418 microg/m3, respectively. The levels of PM2.5 accounted for 80-97% of their respective PM10 concentrations. The average formaldehyde (HCHO) concentrations at fixed and moving sites in night markets ranged from 0 to 0.05 ppm during non-open hours and from 0.02 to 0.27 ppm during open hours. The average concentration of individual polycyclic aromatic hydrocarbons (PAHs) was found in the range of 0.09 x 10(4) to 1.8 x 10(4) ng/m3. The total identified PAHs (TIPs) ranged from 7.8 x 10(1) to 20 x 10(1) ng/m3 during non-open hours and from 1.5 x 10(4) to 4.0 x 10(4) ng/m3 during open hours. Of the total analyzed PAHs, the low-molecular-weight PAHs (two to three rings) were the dominant species, corresponding to an average of 97% during non-open hours and 88% during open hours, whereas high-molecular-weight PAHs (four to six rings) represented 3 and 12% of the total detected PAHs in the gas phase during non-open and open hours, respectively.
Journal of the Air & Waste Management Association (1995) 03/2010; 60(3):369-77. · 1.20 Impact Factor
[show abstract][hide abstract] ABSTRACT: Long-term changes of the ring-widths of Masson pine (Pinus massoniana L.) growing at polluted and unpolluted sites in the Pearl River Delta of south China were compared to evaluate the growth patterns in response to the atmospheric pollution since the late 1970s. Trees at the currently polluted sites had statistically lower ring-widths than those at the unpolluted site since the early 1980s. Standard chronologies at the polluted sites showed consistent decrease in growth since the 1990s. Climate-growth model developed by the multi-stepwise regression at the unpolluted site explained 91.1% of the tree growth variation from year to year and thus it was suggested to be a control chronology index to predict the growth patterns of the pine trees in the study. Growth patterns at the polluted sites estimated by the model revealed negative departure from the control chronology index since the 1980s. The actual and estimated tree-ring indices even at the polluted sites showed synchronousness and statistical correlation in growth patterns prior to the 1980s. The significant increase of the mean differences between the actual and estimated indices and the statistical decrease of the correlation between the control index and the polluted ones after 1980 (especially after 1990) also demonstrated that the growth of pine trees deceased during the most recent years and the atmospheric pollution might be the main factor contributing to the growth decrease. The method of tree-ring analysis demonstrated high suitability and urgent necessity to assess the pine forest health and to improve the forest management in south China where potential forest decline (in particular, current die back) of Masson pine was on process.