Distribution of health survey for England households and participants across variables of interest
| Variable | Households | People aged 16–79 |
|---|---|---|
| Percentages shown in parentheses. | ||
| Survey year | ||
| 1995 | 9084 (34.4) | 15340 (39.1) |
| 1996 | 9350 (35.4) | 15688 (40.0) |
| 1997 | 7992 (30.2) | 8223 (21.0) |
| Social class of head of household | ||
| I (professional) | 1550 (5.9) | 2538 (6.5) |
| II (managerial) | 7091 (26.8) | 11242 (28.6) |
| IIIN (skilled non-manual) | 3827 (14.5) | 4973 (12.7) |
| IIIM (skilled manual) | 6999 (26.5) | 11107 (28.3) |
| IV (semi-skilled) | 3947 (14.9) | 5389 (13.7) |
| V (unskilled) | 1503 (5.7) | 1928 (4.9) |
| Missing | 1509 (5.7) | 2074 (5.3) |
| Urban-rural category | ||
| 1 (wholly urban) | 19621 (74.3) | 28732 (73.2) |
| 2 (urban fringe) | 3135 (11.9) | 4805 (12.2) |
| 3 (semi-rural) | 1625 (6.2) | 2549 (6.5) |
| 4 (wholly rural) | 1708 (6.5) | 2668 (6.8) |
| Missing | 337 (1.3) | 497 (1.3) |
| Ambient air quality index (quintiles across all wards) | ||
| 1 (lowest air pollution) | 1768 (6.7) | 2694 (6.9) |
| 2 | 3479 (13.2) | 5312 (13.5) |
| 3 | 4468 (16.9) | 6733 (17.2) |
| 4 | 7079 (26.8) | 10591 (27.0) |
| 5 (highest air pollution) | 9295 (35.2) | 13424 (34.2) |
| Missing | 337 (1.3) | 497 (1.3) |
| Smoker | ||
| Never | 12260 (31.2) | |
| Former | 14810 (37.7) | |
| Current | 11049 (28.2) | |
| Missing | 1132 (2.9) | |
| Passive smoking exposure (smoker smokes inside household residence) | ||
| No (includes current smokers) | 34334 (87.5) | |
| Yes | 4916 (12.5) | |
| Missing | 1 (0.0) | |
| Sex | ||
| Male | 18100 (46.1) | |
| Female | 21151 (53.9) | |
| Ever diagnosed with asthma | ||
| No | 34477 (87.8) | |
| Yes | 4756 (12.1) | |
| Missing | 18 (0.1) | |
| Maximum valid FEV1 | ||
| Missing | 6346 (16.2) | |
| Non-missing | 32905 (83.8) | |
| Mean FEV1 | 3149.0 ml | |
| Standard deviation | 1012.3 ml | |