Considerations for assessing validity and adversity of biomarker changes

1. Analytical validation
2. Relevance to a clinical condition
3. Appropriateness for proposed use: population versus individual characterisation
4. Presence of multiple converging biomarkers
5. Degree of adherence to Bradford Hill considerations for judging a causal link to air pollution (especially dose/response, replication, biological plausibility and cessation of exposure)
6. Adversity considerations as in table 1 (including adversity of associated clinical end-points)