Inclusion and exclusion criteria for screening articles
| Domain | Inclusion criteria | Exclusion criteria |
| Study type/design | Pooled data analysis of cohort or case–control studies | Ecological study case series |
| Meta-analysis of cohort or case–control studies | ||
| Systematic review of cohort or case–control studies | ||
| Cohort study | ||
| Case–control study | ||
| Study population | Never-smokers (<100 cigarettes in lifetime) | |
| Exposure | Indoor or residential radon exposure | Mining radon exposure |
| Comparator | No or lower radon exposure | |
| Outcome | Lung cancer diagnosis or death | |
| Time of publication | Published from 1 January 1990 to 5 March 2020 | Published before 1990 |
| Publication type | Full-text published article | Editorials, conference proceedings, abstracts, posters, narrative reviews, commentaries, grey literature |
| Language | English | Language other than English |