title: Beneficial cardiovascular effects of reducing exposure to particulate air pollution with a simple facemask.
abstract: BACKGROUND
  Exposure to air pollution is an important risk factor for cardiovascular morbidity and mortality, and is associated with increased blood pressure, reduced heart rate variability, endothelial dysfunction and myocardial ischaemia. Our objectives were to assess the cardiovascular effects of reducing air pollution exposure by wearing a facemask.
  
  
  METHODS
  In an open-label cross-over randomised controlled trial, 15 healthy volunteers (median age 28 years) walked on a predefined city centre route in Beijing in the presence and absence of a highly efficient facemask. Personal exposure to ambient air pollution and exercise was assessed continuously using portable real-time monitors and global positional system tracking respectively. Cardiovascular effects were assessed by continuous 12-lead electrocardiographic and ambulatory blood pressure monitoring.
  
  
  RESULTS
  Ambient exposure (PM2.5 86 +/- 61 vs 140 +/- 113 mug/m3; particle number 2.4 +/- 0.4 vs 2.3 +/- 0.4 x 104 particles/cm3), temperature (29 +/- 1 vs 28 +/- 3 degrees C) and relative humidity (63 +/- 10 vs 64 +/- 19%) were similar (P > 0.05 for all) on both study days. During the 2-hour city walk, systolic blood pressure was lower (114 +/- 10 vs 121 +/- 11 mmHg, P < 0.01) when subjects wore a facemask, although heart rate was similar (91 +/- 11 vs 88 +/- 11/min; P > 0.05). Over the 24-hour period heart rate variability increased (SDNN 65.6 +/- 11.5 vs 61.2 +/- 11.4 ms, P < 0.05; LF-power 919 +/- 352 vs 816 +/- 340 ms2, P < 0.05) when subjects wore the facemask.
  
  
  CONCLUSIONS
  Wearing a facemask appears to abrogate the adverse effects of air pollution on blood pressure and heart rate variability. This simple intervention has the potential to protect susceptible individuals and prevent cardiovascular events in cities with high concentrations of ambient air pollution.
authors.affiliation: Centre for Cardiovascular Sciences, Edinburgh University, Edinburgh, UK. jeremy.langrish@ed.ac.uk.
authors.forename: Jeremy P
authors.initials: JP
authors.lastname: Langrish
authors.forename: Nicholas L
authors.initials: NL
authors.lastname: Mills
authors.forename: Julian Kk
authors.initials: JK
authors.lastname: Chan
authors.forename: Daan Lac
authors.initials: DL
authors.lastname: Leseman
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Aitken
authors.forename: Paul Hb
authors.initials: PH
authors.lastname: Fokkens
authors.forename: Flemming R
authors.initials: FR
authors.lastname: Cassee
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Ken
authors.initials: K
authors.lastname: Donaldson
authors.forename: David E
authors.initials: DE
authors.lastname: Newby
authors.forename: Lixin
authors.initials: L
authors.lastname: Jiang