Detection of ozone toxicity during continuous exercise via the effective dose concept

Area of Science:

• Environmental Health
• Pulmonary Toxicology
• Human Physiology

Background:

• The effective dose concept (concentration × duration × ventilation) is used for ozone (O3) toxicity but primarily validated for resting or intermittent exercise.
• Predicting pulmonary function impairment from O3 exposure during continuous exercise requires further investigation of this concept.

Purpose of the Study:

• To assess the validity of the effective dose concept in predicting pulmonary function impairment during continuous exercise.
• To compare simple product and weighted function methods for calculating effective dose.
• To determine the O3 concentration threshold for toxicity during moderate-intensity continuous exercise.

Main Methods:

• Eight trained males underwent 18 exposure protocols with filtered air and varying O3 concentrations (0.20–0.40 ppm) during continuous exercise (30–80 min).
• Pulmonary function and ventilatory patterns were measured.
• Effective dose was calculated as a simple product and via multiple regression.

Main Results:

• Ozone effective dose correlated significantly with pulmonary function impairment and altered ventilatory patterns.
• Multiple regression highlighted O3 concentration as the primary predictor of toxicity.
• The O3 toxicity threshold during exercise at ~65% maximum O2 uptake was between 0.20 and 0.30 ppm.

Conclusions:

• While the effective dose concept has limitations in predicting individual O3 toxicity, it remains a valuable approach for research.
• Ozone concentration is the most critical factor in determining toxicity during continuous exercise.
• Individual variability in O3 response necessitates further investigation into predictive models.