title: Ambulatory heart rate of professional taxi drivers while driving without their typical psychosocial work stressors: a pilot study.
abstract: BACKGROUND
  Few studies have examined ambulatory cardiovascular physiological parameters of taxi drivers while driving in relation to their occupational hazards. This study aims to investigate and quantify the impact of worksite physical hazards as a whole on ambulatory heart rate of professional taxi drivers while driving without their typical worksite psychosocial stressors.
  
  
  METHODS
  Ambulatory heart rate (HRdriving) of 13 non-smoking male taxi drivers (24 to 67 years old) while driving was continuously assessed on their 6-hour experimental on-road driving in Los Angeles. Percent maximum HR range (PMHRdriving) of the drivers while driving was estimated based on the individual HRdrivingvalues and US adult population resting HR (HRrest) reference data. For analyses, the HRdrivingand PMHRdrivingdata were split and averaged into 5-min segments. Five physical hazards inside taxi cabs were also monitored while driving. Work stress and work hours on typical work days were self-reported.
  
  
  RESULTS
  The means of the ambulatory 5-min HRdrivingand PMHRdrivingvalues of the 13 drivers were 80.5 bpm (11.2 bpm higher than their mean HRrest) and 10.7 % (range, 5.7 to 19.9 %), respectively. The means were lower than the upper limits of ambulatory HR and PMHR for a sustainable 8-hour work (35 bpm above HRrestand 30 % PMHR), although 15-27 % of the 5-min HRdrivingand PMHRdrivingvalues of one driver were higher than the limits. The levels of the five physical hazards among the drivers were modest: temperature (26.4 ± 3.0 °C), relative humidity (40.7 ± 10.4 %), PM2.5(21.5 ± 7.9μg/m3), CO2(1,267.1 ± 580.0 ppm) and noise (69.7 ± 3.0 dBA). The drivers worked, on average, 72 h per week and more than half of them reported that their job were often stressful.
  
  
  CONCLUSIONS
  The impact of physical worksite hazards alone on ambulatory HR of professional taxi drivers in Los Angeles generally appeared to be minor. Future ambulatory heart rate studies including both physical and psychosocial hazards of professional taxi drivers are warranted.
authors.affiliation: Center for Occupational and Environmental Health, University of California Irvine, 100 Theory, Suite 100, Irvine, CA 92617 USA.
authors.forename: BongKyoo
authors.initials: B
authors.lastname: Choi
authors.affiliation: Center for Occupational and Environmental Health, University of California Irvine, 100 Theory, Suite 100, Irvine, CA 92617 USA ; Department of Occupational Health, Catholic University of Daegu, Gyeongsan, South Korea.
authors.forename: SangJun
authors.initials: S
authors.lastname: Choi
authors.affiliation: Center for Occupational and Environmental Health, University of California Irvine, 100 Theory, Suite 100, Irvine, CA 92617 USA ; Department of Occupational and Environmental Health, Yong In University, Yongin, South Korea.
authors.forename: JeeYeon
authors.initials: J
authors.lastname: Jeong
authors.affiliation: Center for Occupational and Environmental Health, University of California Irvine, 100 Theory, Suite 100, Irvine, CA 92617 USA ; Department of Family Medicine, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: JiWon
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Environmental Health Sciences, University of California Los Angeles, Los Angeles, CA USA.
authors.forename: Shi
authors.initials: S
authors.lastname: Shu
authors.affiliation: Department of Environmental Health Sciences, University of California Los Angeles, Los Angeles, CA USA.
authors.forename: Nu
authors.initials: N
authors.lastname: Yu
authors.affiliation: Center for Occupational and Environmental Health, University of California Irvine, 100 Theory, Suite 100, Irvine, CA 92617 USA ; Department of Preventive Medicine, Yonsei University Wonju College of Medicine, Wonju, South Korea.
authors.forename: SangBaek
authors.initials: S
authors.lastname: Ko
authors.affiliation: Department of Environmental Health Sciences, University of California Los Angeles, Los Angeles, CA USA.
authors.forename: Yifang
authors.initials: Y
authors.lastname: Zhu
keywords: Los Angeles; Percent maximum heart rate; Physical hazards; Psychosocial hazards; Work hours; Work stress