Using lichen as bioindicator of air pollution: Acid deposition Monitoring and Assessment Third country Training

The different sources of potential confounding in time series studies of air pollution and mortality can be broadly classified as either measured or unmeasured. Important measured confounders include weather variables such as temperature and dewpoint temperature. Daily temperature measurements are readily available for metropolitan areas in the USA and numer- ous studies have demonstrated a relationship between temperature and mortality which is gen- erally positive for warm summer days and negative for cold winter days (e.g. Curriero et al. (2002)). One approach to adjusting for confounding by temperature is to include non-linear functions of current and previous day temperature (and dewpoint) in the model (Schwartz, 1994a; Kelsall et...