Table 3– Lessons learned from reviewing the air pollution and chronic obstructive pulmonary disease (COPD) evidence and the remaining uncertainties in interpreting this literature
TopicLimitations in interpretation
Epidemiological evidenceIn spite of plausible models of biological mechanisms, direct epidemiological evidence of the long-term effects of air pollution on COPD prevalence and incidence remains suggestive but not conclusive
COPD phenotypesA major obstacle to understanding causality relates to loose and heterogeneous definitions of COPD phenotypes
Life-time course of diseasesAir pollution affects the growth and decline of lung function but the link between these processes and the development of COPD is not well investigated
Role of acute versus long-term effectsAir pollution causes acute respiratory symptoms and exacerbations of COPD An accumulation of damage to airways resulting from these acute effects is a plausible basis for any link between air pollution and the development of COPD, but direct evidence is lacking