| Adults living in participating households | 17 355 | 17 656 | 9300 | 17 488 |
| Adults who completed health questionnaire (% of adults in participating households) | 16 055 (92.5) | 16 443 (93.1) | 8582 (92.3) | 15 647 (89.5) |
| White adults who completed questionnaire | 15 119 | 15 410 | 8086 | 14 546 |
| White adults with lung function measures (% of white adults who completed questionnaire) | 12 428 (82.2) | 12 969 (84.2) | 6829 (84.5) | 10 749 (73.9) |
| White adults with complete data on lung function, covariates and all four pollutants (% of white adults who completed questionnaire) | 11 400 (75.4) | 11 963 (77.6) | 6359 (78.6) | 10 607 (72.9) |