Objectives Epidemiological studies of air pollution on cardiovascular health show associations of cardiac mortality and admissions with exposure to nitrogen dioxide (NO2) at low concentrations. These associations could be causal or NO2 could be acting as a surrogate measure for another air pollutant, most likely ultrafine particles. No studies of cardiac susceptibility to acute exposure to NO2 have been undertaken.
Methods Randomised controlled exposures to NO2 (400 ppb for 1 h) and air in subjects with coronary heart disease and impaired left ventricular systolic function not taking β adrenoceptor blocking drugs.
Results There were no significant changes in heart rate, blood pressure, leucocyte coping capacity or any heart rate variability measure following NO2 exposure compared with air.
Conclusion These findings suggest that NO2 does not affect heart rate variability at these concentrations (which are high for urban background levels) and in the absence of other pollutants. While a synergistic effect has not been ruled out, these data lend support to the idea that the epidemiological data associating cardiac outcomes with NO2 are more likely due to an associated pollutant rather than NO2 itself.
- Nitrogen dioxide
- air pollution
- coronary heart disease
- heart rate variability
- occupational asthma
- clinical medicine
- time series study
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Funding This project was supported by a grant from the Colt Foundation.
Competing interests None.
Patient consent Obtained.
Ethics approval Ethical approval was provided by the Grampian NHS Regional Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.