The vast majority of patients with chronic respiratory disease live in low- and middle-income countries (LMICs). Paradoxically, relevant interventions often fail to be effective particularly in these settings, as LMICs lack solid evidence on how to implement interventions successfully. Therefore, we aimed to identify factors critical to the implementation of lung health interventions in LMICs, and weight their level of evidence.This systematic review followed Cochrane methodology and PRISMA reporting standards. We searched eight databases without date- or language restrictions in July 2019, and included all relevant original, peer-reviewed articles. Two researchers independently selected articles, critically appraised them (using CASP/MetaQAT), extracted data, coded factors (following CFIR), and assigned levels of confidence in the factors (via GRADE-CERQual). We meta-synthesised levels of evidence of the factors based on their frequency and the assigned level of confidence. (PROSPERO:CRD42018088687)We included 37 articles out of 9111 screened. Studies were performed across the globe in a broad range of settings. Factors identified with a high level of evidence were 1) Understanding needs of local users, 2) ensuring Compatibility of interventions with local contexts (cultures, infrastructures), 3) identifying influential stakeholders and applying Engagement strategies, 4) ensuring adequate Access to knowledge and information, and 5) addressing Resource Availability All implementation factors and their level of evidence were synthesised in an implementation tool.To conclude, this study identified implementation factors for lung health interventions in LMICs, weighted their level of evidence, and integrated the results into an implementation tool for practice. Policymakers, non-governmental organisations, practitioners, and researchers may use this FRESH AIR Implementation tool to develop evidence-based implementation strategies for related interventions. This could increase interventions' implementation success, thereby optimising the use of already-scarce resources and improving health outcomes.