A model for the effect on health of repeated exposure to ozone

Exposure to ambient ozone can result in lung function decrement in humans. Clinical studies in which humans were repeatedly exposed to ozone have revealed that lung function decrement decreases after each additional exposure event. Ozone concentrations in the ambient atmosphere show strong seasonal, episodic, and diurnal fluctuations. Accordingly, in quantitative risk analysis a model is needed, which accounts for the time dependence of the lung function decrement on observed exposure patterns. This paper presents a toxico-dynamic model predicting lung function and cellular injury and repair over time. Any ozone exposure pattern can be used as an input to the model, to predict the development of lung function decrement in time. The model incorporates the biological mechanisms generally believed to play a role in the lung function decrement due to ozone exposure. A comparison was made of the model’s predictions and observed lung function decrements in seven different clinical studies. This type of ozone effect modelling and its further progress may contribute to risk evaluation and assessment of ambient exposures.