Inclusion criteria | Exclusion criteria |
Original articles Epidemiological or observational studies such as cross-sectional, cohort, or case-control studies Only human studies Articles published in English, French Focus on traffic related air pollution Focus on population working or living along a major/trunk road Studies had reported clearly at least one of the exposure variables related to TRAP Studies had reported respiratory symptoms or respiratory diseases Studies examined the association between traffic related air pollution (TRAP) and development of respiratory symptoms or respiratory diseases | Non-research studies, off-topic studies, studies concerning populations not exclusively exposed to traffic-related air pollution Review, commentaries Animal studies Abstract or full articles not available Studies about TRAP but not on major/trunk road Studies that measured exclusively pollution exposure to non-traffic related air pollution |