Comparison of daily and seasonal exposures of young monkeys to ozone

Walter S. Tyler, Nancy K. Tyler, Jerold A Last, Martha J. Gillespie, Thomas J. Barstow

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


Oxidant air pollution tends to occur in both seasonal and daily cycles of polluted and clean air. To compare the effects of these 2 cycles, we exposed 2 groups of 7-month-old male monkeys to 0.25 ppm (0.49 mg/m3) of ozone (UV photometric standard) 8 h/day either daily or, in the seasonal model, days of alternate months during a total exposure period of 18 months. This is a longer ozone exposure period than any previously reported. A control group breathed only filtered air. Young monkeys were studied as their lungs are similar to those of man and their lungs, like those of man, grow over a period of several years. Monkeys from the seasonal exposure model, but not those exposed daily, had significantly increased total lung collagen content, chest wall compliance, and inspiratory capacity. All monkeys exposed to ozone had respiratory bronchiolitis with significant increases in related morphometric parameters. The only significant difference between seasonal and daily groups was in the volume fraction of macrophages. Even though the seasonally exposed monkeys were exposed to the same concentration of ozone for only half as many days, they had larger biochemical and physiological alterations and equivalent morphometric changes as those exposed daily. Lung growth was not completely normal in either exposed group. Long-term effects of oxidant air pollutants which have a seasonal occurence may be more dependent upon the sequence of polluted and clean air than on the total number of days of pollution. Estimations of the risks of human exposure to seasonal air pollutants from effects observed in animals exposed daily may underestimate long-term pulmonary damage.

Original languageEnglish (US)
Pages (from-to)131-144
Number of pages14
Issue number2
StatePublished - 1988
Externally publishedYes


  • Chest wall compliance
  • Lung collagen
  • Ozone
  • Post-exposure effects
  • Respiratory bronchiolitis

ASJC Scopus subject areas

  • Toxicology


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