Antioxidant supplementation and respiratory functions among workers exposed to high levels of ozone

Am J Respir Crit Care Med. 1998 Jul;158(1):226-32. doi: 10.1164/ajrccm.158.1.9712053.


Ozone exposure has been related to adverse respiratory effects, in particular to lung function decrements. Antioxidant vitamins are free-radical scavengers and could have a protective effect against photo-oxidant exposure. To evaluate whether acute effects of ozone on lung functions could be attenuated by antioxidant vitamin supplementation, we conducted a randomized trial using a double-blind crossover design. Street workers (n = 47) of Mexico City were randomly assigned to take daily a supplement (75 mg vitamin E, 650 mg vitamin C, 15 mg beta carotene) or a placebo and were followed from March to August 1996. Pulmonary function tests were done twice a week at the end of the workday. During the follow-up, the mean 1-h maximum ozone level was 123 ppb (SD = 40). During the first phase, ozone levels were inversely associated with FVC (beta = -1.60 ml/ppb), FEV1 (beta = -2.11 ml/ppb), and FEF25-75 (beta = -4.92 ml/ppb) (p < 0.05) in the placebo group but not in the supplement group. The difference between the two groups was significant for FVC, FEV1, and FEF25-75 (p < 0.01). During the second phase, similar results were observed, but the lung function decrements in the placebo group were smaller, suggesting that the supplementation may have had a residual protective effect on the lung. These results need to be confirmed in larger supplementation studies.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Antioxidants / therapeutic use*
  • Cross-Over Studies
  • Dietary Supplements*
  • Double-Blind Method
  • Humans
  • Male
  • Middle Aged
  • Occupational Diseases / prevention & control
  • Occupational Exposure*
  • Ozone / adverse effects*
  • Respiration / drug effects*
  • Respiratory Function Tests
  • Respiratory Tract Diseases / prevention & control
  • Spirometry
  • Vitamin E / blood
  • beta Carotene / blood
  • beta Carotene / therapeutic use*


  • Antioxidants
  • beta Carotene
  • Vitamin E
  • Ozone