Meteorological factors and ambient bacterial levels in a subtropical urban environment.
We conducted a study to investigate the characteristics and determinants of ambient bacteria in Taipei, Taiwan from August 2004 to March 2005. We monitored ambient culturable bacteria in Shin-Jhuang City, an urban area in the Taipei metropolitan areas, using duplicate Burkard Portable Air Samplers with R2A agar. The average concentration of total bacteria was 1,986 colony-forming units per cubic meter of air (CFU/m(3)) (median = 780 CFU/m(3)) over the study period, with the highest level in autumn. Most bacterial taxa had similar seasonal variation, with higher concentrations in autumn and winter. During the study period, Gram negative rods and cocci were predominant. Multivariate analyses indicated that wind speed and wind direction significantly influenced ambient bacterial distribution. Temperature and relative humidity were also important environmental factors positively associated with ambient bacterial concentrations. We observed statistically significant relationships between ambient bacteria and air pollutants, including sulfur dioxide (SO(2)), ozone, particulate matter (aerodynamic diameter ≤10 μm (PM(10))), methane and total hydrocarbons. The concentrations of methane and total hydrocarbons during the previous day were positively associated with total bacteria and Gram negative rods, respectively. Ozone level on the previous day had a negative relationship with Gram negative cocci. SO(2) level with a 3-day lag was positively correlated with concentrations of both total bacteria and Gram negative cocci. In the future, more longitudinal studies are needed to confirm the relationships and possible mechanisms between ambient bacteria and meteorological factors, as well as to evaluate the ecological and health impacts of ambient bacteria.
School of Public Health, Taipei Medical University, 5F Health Science Building, No. 250 Wu-Hsing St., Taipei, Taiwan, Republic of China.
Yi-Hua
YH
Wu
Chang-Chuan
CC
Chan
Ginger L
GL
Chew
Po-Wen
PW
Shih
Chung-Te
CT
Lee
H Jasmine
HJ
Chao
D000391:Air Microbiology; D000393:Air Pollutants / Q000032:analysis* / Q000145:classification; D001419:Bacteria / Q000145:classification / Q000302:isolation & purification*; D002947:Cities; D004784:Environmental Monitoring; D008685:Meteorological Concepts; D008697:Methane / Q000032:analysis; D010126:Ozone / Q000032:analysis; D052638:Particulate Matter / Q000032:analysis; D013458:Sulfur Dioxide / Q000032:analysis; D013624:Taiwan
D000393:Air Pollutants; D052638:Particulate Matter; D013458:Sulfur Dioxide; D010126:Ozone; D008697:Methane