Quality scores of the included studies
| Exposure, first author (year) | Study design | Follow-up time | Response rate | Exposure measure | Exposure–response relation | Confounder control | Total score |
| Cotton workers | |||||||
| Glindmeyer (1991)30 | 1 | 0 | 0 | 1 | 1 | 0 | 3 |
| Wang (2003)31 | 1 | 0 | 1 | 1 | 1 | 1 | 5 |
| Wang (2005)14 | 1 | 1 | 1 | 1 | 1 | 1 | 6 |
| Grain workers | |||||||
| Huy (1991)32 | 1 | 1 | 1 | 1 | 1 | 1 | 6 |
| Olfert (2005)33 | 1 | 0 | 0 | 0 | 1 | 1 | 3 |
| Pahwa (2008)15 | 1 | 1 | 1 | 0 | 1 | 1 | 5 |
| Post (1998)34 | 1 | 0 | 0 | 1 | 1 | 1 | 4 |
| Senthilselvan (2010)35 | 1 | 1 | 1 | 0 | 1 | 1 | 5 |
| Farmers | |||||||
| Bolund (2015)36 | 1 | 1 | 1 | 1 | 1 | 1 | 6 |
| Gainet (2007)37 | 1 | 1 | 1 | 0 | 1 | 1 | 5 |
| Iversen (2000)20 | 1 | 1 | 1 | 0 | 0 | 1 | 4 |
| Mauny (1997)38 | 1 | 0 | 1 | 0 | 1 | 0 | 3 |
| Schwartz (1995)21 | 1 | 0 | 1 | 1 | 1 | 1 | 5 |
| Senthilselvan (1997) 39 | 1 | 0 | 1 | 0 | 0 | 1 | 3 |
| Thaon (2011)16 | 1 | 1 | 1 | 0 | 1 | 1 | 5 |
| Vogelzang (1998)40 | 1 | 0 | 1 | 1 | 1 | 0 | 4 |
| Paper workers | |||||||
| Sigsgaard (2004)19 | 1 | 1 | 1 | 1 | 1 | 0 | 5 |
| Wood workers | |||||||
| Glindmeyer (2008)41 | 1 | 0 | 0 | 1 | 1 | 1 | 4 |
| Jacobsen (2008)42 | 1 | 1 | 1 | 1 | 1 | 1 | 6 |
| Noertjojo (1996)43 | 1 | 1 | 1 | 1 | 1 | 1 | 6 |
Study design (longitudinal=1), follow-up time (≥6 years=1, <6 years=0), response rate (>50%=1, <50% or unknown=0), exposure measure (dust measurements=1, no dust measurements=0), exposure–response relation (analysed=1, not analysed=0), and confounder control (all of smoking, sex, age and height=1, other=0).