Model misspecification, measurement error, and apparent supralinearity in the concentration-response relationship between PM2.5 and mortality.

A growing number of studies have produced results that suggest the shape of the concentration-response (C-R) relationship between PM2.5 exposure and mortality is "supralinear" such that incremental risk is higher at the lowest exposure levels than at the highest exposure levels. If the C-R function is in fact supralinear, then there may be significant health benefits associated with reductions in PM2.

A simulation-based assessment of the ability to detect thresholds in chronic risk concentration-response functions in the presence of exposure measurement error.

An important question when setting appropriate air quality standards for fine particulate matter (PM2.5) is whether there exists a "threshold" in the concentration-response (C-R) function, such that PM2.5 levels below this threshold are not expected to produce adverse health effects.

Integrated Uncertainty Analysis for Ambient Pollutant Health Risk Assessment: A Case Study of Ozone Mortality Risk.

The U.S. Environmental Protection Agency (EPA) uses health risk assessment to help inform its decisions in setting national ambient air quality standards (NAAQS).

Uncertainty in the estimated risk of lung function decrements owing to ozone exposure.

In the most recent Health Risk and Exposure Assessment (HREA) for Ozone, the US Environmental Protection Agency (EPA) used an exposure-response function estimated on clinical data to calculate the risk of lung function decrements in a series of population-level simulations. These risk estimates are subject to both statistical uncertainty (which arises because the exposure-response function was estimated on a sample of clinical observations) and model uncertainty (which arises because there are different plausible ways to model the relationship between ozone exposure and lung function decrement). In this paper, we describe and apply an approach that allows us to estimate the statistical uncertainty present in these risk estimates.