For chronic bronchitis, our assessment relies on one
study.13 The advantage of the study is the reporting of
effects of PM on the incidence of chronic bronchitis
among a population with very low rates of smoking. This
measure was particularly useful for the economic
valuation and had been used before.14 It is of note,
however, that the Swiss SAPALDIA study24 corroborates
the US findings, showing increased prevalence of
chronic bronchitis symptoms also in Europe, as shown
before in the USA