Study site classification by urbanisation, indoor and outdoor pollution, and altitude
| Degree of urbanisation | Use of biomass fuel | Outdoor air pollution | Altitude | |
| Lima | Highly urbanised | Rare | High | Sea level |
| Tumbes | Semiurban | Moderately prevalent | Low | Sea level |
| Puno, urban | Urban | Rare | Low | 3825 m above sea level |
| Puno, rural | Rural | Highly prevalent | Low | 3825 m above sea level |
Table adapted from previous work.20