Characterizations and relationships between indoor and outdoor bioaerosols were examined in an occupied office building, equipped with an air conditioning (HVAC) system, in Tempe, Arizona, USA. A two-stage microbial a...Characterizations and relationships between indoor and outdoor bioaerosols were examined in an occupied office building, equipped with an air conditioning (HVAC) system, in Tempe, Arizona, USA. A two-stage microbial air sampler was used to collect bioaerosols both inside and outside the office at fixed locations in space and at regular time intervals from August to December, 2000. Simultaneous measurements of bioaerosol, temperature, relative humidity, light intensity and wind speed were performed to explore the effects of environmental factors on bioaerosol levels. Twenty species of airborne bacteria and four genera of airborne fungi were found in our samples. The particle sizes of most outdoor and indoor bioaerosols were larger than 8.0 mm. According to the measurements of sampling days, the concentrations of outdoor bioaerosols were highest in the morning, but declined in the afternoon and reached the lowest point in the evening. The concentration peak of indoor bioaerosol (especially at the lower level) occurred in the evening, suggesting that the concentration of indoor bioaerosols follows that of outdoors, but with a time delay due to the lag associated with indoor-outdoor air exchange. With regard to the effects of four environmental factors temperature, relative humidity, light intensity, and wind speed, the relative humidity had the most pronounced influence on the outdoor bioaerosol concentrations with the number of bacteria and fungi increasing sharply on a day of high relative humidity in the desert area.展开更多
Traffic is a main source of air pollutants in urban areas and consequently daily peak exposures tend to occur during commuting.Personal exposure to particulate matter(PM)was monitored while cycling and travelling by b...Traffic is a main source of air pollutants in urban areas and consequently daily peak exposures tend to occur during commuting.Personal exposure to particulate matter(PM)was monitored while cycling and travelling by bus,car and metro along an assigned route in Lisbon(Portugal),focusing on PM_(2.5) and PM_(1)0(PM with aerodynamic diameter<2.5 and 10μm,respectively)mass concentrations and their chemical composition.In vehicles,the indoor-outdoor interplay was also evaluated.The PM_(2.5) mean concentrations were 28±5,31±9,34±9 and 38±21μg/m 3 for bus,bicycle,car and metro modes,respectively.Black carbon concentrations when travelling by car were 1.4 to 2.0 times higher than in the other transport modes due to the closer proximity to exhaust emissions.There are marked differences in PM chemical composition depending on transport mode.In particular,Fe was the most abundant component of metro PM,derived from abrasion of rail-wheel-brake interfaces.Enhanced concentrations of Zn and Cu in cars and buses were related with brake and tyre wear particles,which can penetrate into the vehicles.In the motorised transport modes,Fe,Zn,Cu,Ni and K were correlated,evidencing their common traffic-related source.On average,the highest inhaled dose of PM_(2.5) was observed while cycling(55μg),and the lowest in car travels(17μg).Cyclists inhaled higher doses of PM_(2.5) due to both higher inhalation rates and longer journey times,with a clear enrichment in mineral elements.The presented results evidence the importance of considering the transport mode in exposure assessment studies.展开更多
The time series of indoor and outdoor particle number concentrations in a naturally ventilated residential building in Xi＇an were tested simultaneously for 7 days in summer. The relationships between indoor and outdo...The time series of indoor and outdoor particle number concentrations in a naturally ventilated residential building in Xi＇an were tested simultaneously for 7 days in summer. The relationships between indoor and outdoor concentrations were examined and discussed, and linear regression analysis was employed to correlate the indoor and outdoor concentrations. The diurnal cycles of indoor and outdoor particle concentrations of different particle size ranges all showed positive correlations between indoor and outdoor number concentrations, The I/O ratios of number concentrations varied with the increase of particle size in the range of 0.89 （±0.19） to 0.99 （±0.15）.展开更多
文摘Characterizations and relationships between indoor and outdoor bioaerosols were examined in an occupied office building, equipped with an air conditioning (HVAC) system, in Tempe, Arizona, USA. A two-stage microbial air sampler was used to collect bioaerosols both inside and outside the office at fixed locations in space and at regular time intervals from August to December, 2000. Simultaneous measurements of bioaerosol, temperature, relative humidity, light intensity and wind speed were performed to explore the effects of environmental factors on bioaerosol levels. Twenty species of airborne bacteria and four genera of airborne fungi were found in our samples. The particle sizes of most outdoor and indoor bioaerosols were larger than 8.0 mm. According to the measurements of sampling days, the concentrations of outdoor bioaerosols were highest in the morning, but declined in the afternoon and reached the lowest point in the evening. The concentration peak of indoor bioaerosol (especially at the lower level) occurred in the evening, suggesting that the concentration of indoor bioaerosols follows that of outdoors, but with a time delay due to the lag associated with indoor-outdoor air exchange. With regard to the effects of four environmental factors temperature, relative humidity, light intensity, and wind speed, the relative humidity had the most pronounced influence on the outdoor bioaerosol concentrations with the number of bacteria and fungi increasing sharply on a day of high relative humidity in the desert area.
基金European Union through the project LIFE Index-Air(LIFE15 ENV/PT/000674)supported by Portuguese Foundation for Science and Technology(FCT)through the projects Expo LIS(LISBOA-01-0145-FEDER-032088)and UID/Multi/04349/2013,the contract CEECIND/04228/2018 and the Ph D grants SFRH/BD/129149/2017 and SFRH/BD/147074/2019。
文摘Traffic is a main source of air pollutants in urban areas and consequently daily peak exposures tend to occur during commuting.Personal exposure to particulate matter(PM)was monitored while cycling and travelling by bus,car and metro along an assigned route in Lisbon(Portugal),focusing on PM_(2.5) and PM_(1)0(PM with aerodynamic diameter<2.5 and 10μm,respectively)mass concentrations and their chemical composition.In vehicles,the indoor-outdoor interplay was also evaluated.The PM_(2.5) mean concentrations were 28±5,31±9,34±9 and 38±21μg/m 3 for bus,bicycle,car and metro modes,respectively.Black carbon concentrations when travelling by car were 1.4 to 2.0 times higher than in the other transport modes due to the closer proximity to exhaust emissions.There are marked differences in PM chemical composition depending on transport mode.In particular,Fe was the most abundant component of metro PM,derived from abrasion of rail-wheel-brake interfaces.Enhanced concentrations of Zn and Cu in cars and buses were related with brake and tyre wear particles,which can penetrate into the vehicles.In the motorised transport modes,Fe,Zn,Cu,Ni and K were correlated,evidencing their common traffic-related source.On average,the highest inhaled dose of PM_(2.5) was observed while cycling(55μg),and the lowest in car travels(17μg).Cyclists inhaled higher doses of PM_(2.5) due to both higher inhalation rates and longer journey times,with a clear enrichment in mineral elements.The presented results evidence the importance of considering the transport mode in exposure assessment studies.
基金This work was supported by the National Natural Science Foundation of China （Grant No. 50578034, Grant No. 40475047）Shanghai Educational Development Foundation Titled ＂Shuguang Project＂, P.R. China （Grant No. 03SG30）.
文摘The time series of indoor and outdoor particle number concentrations in a naturally ventilated residential building in Xi＇an were tested simultaneously for 7 days in summer. The relationships between indoor and outdoor concentrations were examined and discussed, and linear regression analysis was employed to correlate the indoor and outdoor concentrations. The diurnal cycles of indoor and outdoor particle concentrations of different particle size ranges all showed positive correlations between indoor and outdoor number concentrations, The I/O ratios of number concentrations varied with the increase of particle size in the range of 0.89 （±0.19） to 0.99 （±0.15）.
