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The effect of sulphurous air pollutant exposures on symptoms, lung function, exhaled nitric oxide, and nasal epithelial lining fluid antioxidant concentrations in normal and asthmatic adults
  1. W S Tunnicliffe1,
  2. R M Harrison2,
  3. F J Kelly3,
  4. C Dunster3,
  5. J G Ayres4
  1. 1Department of Respiratory Medicine, Heartlands Hospital, Bordesley Green East, Birmingham B9 5SS, UK
  2. 2Division of Environmental Health & Risk Management, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
  3. 3School of Health and Life Sciences, Franklin-Wilkins Buildings, King’s College London, London SE1 9NN, UK
  4. 4Department of Environmental & Occupational Medicine, Liberty Safe Work Research Centre, University of Aberdeen, Aberdeen AB25 2ZP, UK
  1. Correspondence to:
 Prof. J G Ayres
 Department of Environmental & Occupational Medicine, Liberty Safe Work Research Centre, University of Aberdeen, Foresterhill Road, Aberdeen AB25 2ZP, UK; j.g.ayres{at}


Aims: To explore the effects in normal and asthmatic adults of exposure to 200 ppb sulphur dioxide (SO2) and 200 μg/m3 and 2000 μg/m3 aerosols of ammonium bisulphate (AB) and sulphuric acid (SA) (MMD 0.3 μm).

Methods: Exposures were placebo controlled, for one hour at rest, double blind in random order. ΔFEV1 was the primary outcome; secondary outcomes included symptoms, ventilation, exhaled nitric oxide (NO) concentrations, and nasal lavage fluid ascorbic (AA) and uric acid (UA) concentrations.

Results: There were no significant changes in spirometry or symptoms with any exposure in either group. SO2 exposure was associated with an increased respiratory rate relative to air exposure in the asthmatic group (SO2: 958.9 breaths/hour; air: 906.8 breaths/hour) but the mean volume breathed did not differ significantly (SO2: 318.8 litres; air: 311.4 litres). AB exposures were associated with a significant rise in [NO] in the asthmatic (+1.51 ppb, and +1.39 ppb), but not in the normal group. Mean pre- and post-exposure [AA] tended to be higher in the normal than in the asthmatic group. Within each group, [AA] did not change significantly with any exposure. Post-exposure [UA] were greater than pre-exposure concentrations for all exposures, significantly so in the normal group for all exposures except SO2. There were no significant differences in the mean change in [UA] for any exposure relative to air.

Conclusions: The pollutant exposure concentrations employed in this study were generally much greater than ambient. It is unlikely that short lived exposures at lower concentrations would show significant effects, but effects of longer term lower concentration exposures cannot be ruled out.

  • air pollution
  • sulphuric acid
  • ammonium bisulphate
  • antioxidants
  • mechanisms
  • AA, ascorbic acid
  • AB, ammonium bisulphate
  • BMA, bottled medical air
  • ELF, epithelial lining fluid
  • eNO, exhaled nitric oxide
  • FEV, forced expiratory volume
  • FVC, forced vital capacity
  • MMEF, maximum mid-expiratory flow
  • NL, nasal lavage
  • SA, sulphuric acid
  • UA, uric acid

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