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Adaptation to ozone: duration of effect
The American Review of Respiratory Disease
|May 1, 1981
Summary
Repeated exposure to ozone (O3) causes the lungs to adapt, reducing immediate pulmonary function changes. This adaptation varies individually and typically lasts less than two weeks.
Area of Science:
- Environmental Health
- Pulmonary Medicine
- Toxicology
Background:
- Ozone (O3) is a major air pollutant with known respiratory effects.
- Repeated exposure to ozone can lead to an adaptive response, diminishing subsequent pulmonary function decrements.
- Individual variability in ozone sensitivity and adaptation is a significant factor in respiratory health outcomes.
Purpose of the Study:
- To determine the time course of adaptation to repeated ozone exposure.
- To investigate the persistence of this adaptive response over time.
- To identify factors influencing the development and duration of ozone adaptation.
Main Methods:
- Twenty-four subjects underwent intermittent exercise with controlled exposures to filtered air and 0.5 ppm ozone over several days.
- Pulmonary function, specifically FEV1 (Forced Expiratory Volume in 1 second), was measured to assess the impact of ozone.
- Subjects were re-exposed to ozone at 1, 2, or 3-week intervals after initial adaptation to evaluate persistence.
Main Results:
- The most significant decrease in FEV1 occurred on the second day of ozone exposure.
- Adaptation to ozone required 2 to 5 consecutive days of exposure, varying among individuals.
- Adaptation duration showed individual variability, lasting from 7 to 20 days, with shorter persistence in more sensitive individuals.
Conclusions:
- Repeated daily ozone exposure induces an adaptive response that lessens pulmonary function changes.
- More sensitive individuals require a greater number of sequential exposures to achieve adaptation.
- The duration of ozone adaptation is variable and generally short-lived, particularly for sensitive populations.