Original Article

Journal of Exposure Science and Environmental Epidemiology (2016) 26, 133–140; doi:10.1038/jes.2015.66; published online 21 October 2015

Impact of traffic-related air pollution on acute changes in cardiac autonomic modulation during rest and physical activity: a cross-over study

Tom Cole-Hunter1,2,3, Scott Weichenthal4, Nadine Kubesch1,2,3, Maria Foraster5, Glòria Carrasco-Turigas1,2,3, Laura Bouso1,2,3, David Martínez1,2,3, Dane Westerdahl6, Audrey de Nazelle7 and Mark Nieuwenhuijsen1,2,3

  1. 1Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Spain
  2. 2Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
  3. 3Department of Experimental and Health Sciences, Universitat Pompeu Fabra (UPF), Barcelona, Spain
  4. 4Air Health Effects Science Division, Health Canada, Ottawa, Canada
  5. 5Swiss Tropical and Public Health Institute, Basel, Switzerland
  6. 6Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, USA
  7. 7Centre for Environmental Policy, Imperial College London, London, England

Correspondence: Dr. Tom Cole-Hunter, Centre for Research in Environmental Epidemiology, C/Doctor Aiguader 88, Barcelona 08003, Spain. Tel.: +34 93214 7317. Fax: +34 93214 7302. E-mail: tcolehunter@creal.cat

Received 20 March 2015; Revised 27 August 2015; Accepted 29 August 2015
Advance online publication 21 October 2015



People are often exposed to traffic-related air pollution (TRAP) during physical activity (PA), but it is not clear if PA modifies the impact of TRAP on cardiac autonomic modulation. We conducted a panel study among 28 healthy adults in Barcelona, Spain to examine how PA may modify the impact of TRAP on cardiac autonomic regulation. Participants completed four 2-h exposure scenarios that included either rest or intermittent exercise in high- and low-traffic environments. Time- and frequency-domain measures of heart rate variability (HRV) were monitored during each exposure period along with continuous measures of TRAP. Linear mixed-effects models were used to estimate the impact of TRAP on HRV as well as potential effect modification by PA. Exposure to TRAP was associated with consistent decreases in HRV; however, exposure–response relationships were not always linear over the broad range of exposures. For example, each 10μg/m3 increase in black carbon was associated with a 23% (95% CI: −31, −13) decrease in high frequency power at the low-traffic site, whereas no association was observed at the high-traffic site. PA modified the impact of TRAP on HRV at the high-traffic site and tended to weaken inverse associations with measures reflecting parasympathetic modulation (P≤0.001). Evidence of effect modification at the low-traffic site was less consistent. The strength and direction of the relationship between TRAP and HRV may vary across exposure gradients. PA may modify the impact of TRAP on HRV, particularly at higher concentrations.


heart rate variability; noise; particles; physical activity; traffic-related air pollution


BC, black carbon; BMI, body mass index; BP, blood pressure; b.p.m., beats per minute; HF, high frequency power; HR, heart rate; HRV, heart rate variability; LAeq, A-weighted decibels (dB) of sound pressure; LF, low frequency power; LF:HF, ratio of low to high frequency power; NO, nitrogen oxide; NO2, nitrogen dioxide; NOX, nitrogen oxides; PM2.5, particulate matter ≤2.5μm (fine); RMSSD, root mean square of successive differences in adjacent NN intervals; SDNN, standard deviation of normal to normal intervals; TRAP, traffic-related air pollution; UFP, ultrafine particle.