The baseline characteristics of participants and death rates according to exposure category
| Mean NO2 concentration for 2000–2005 (μg/m3) | ||||
| ≤20.3 (n=3008)* | 20.3–26.5 (n=3007)* | 26.5–32.1 (n=3007)* | >32.1 (n=3007)* | |
| Person-years | 15928 | 15725 | 15805 | 15727 |
| Mean age, years (SD) | 74 (5.4) | 74 (5.4) | 74 (5.4) | 74 (5.5) |
| Female (%)† | 1484 (49) | 1452 (48) | 1466 (49) | 1473 (49) |
| Mean body mass index (SD)‡ | 22 (3.0) | 22 (3.1) | 22 (3.1) | 22 (3.0) |
| Smoking category† | ||||
| Non-smoker | 2069 (69) | 2062 (69) | 2040 (68) | 2063 (69) |
| Ex-smoker | 356 (12) | 348 (12) | 353 (12) | 343 (11) |
| Current smoker | 464 (15) | 480 (16) | 488 (16) | 475 (16) |
| Unknown | 119 (4.0) | 117 (3.9) | 126 (4.2) | 126 (4.2) |
| Hypertension (%) | 979 (33) | 915 (30) | 975 (32) | 893 (30) |
| Diabetes (%) | 218 (7.2) | 229 (7.6) | 225 (7.5) | 239 (7.9) |
| Financial capability† | ||||
| Capable | 1572 (52) | 1677 (56) | 1699 (57) | 1748 (58) |
| Non-capable | 964 (32) | 887 (30) | 861 (29) | 845 (28) |
| Unknown | 472 (16) | 443 (15) | 447 (15) | 414 (14) |
| Death rate (%)† | ||||
| All cause | 318 (11) | 311 (10) | 322 (11) | 281 (9.3) |
| Cardiopulmonary (I10–70/J00–J99) | 131 (4.4) | 149 (5.0) | 147 (4.9) | 166 (5.5) |
| Circulatory disease (I10–70) | 82 (2.7) | 108 (3.6) | 101 (3.4) | 103 (3.4) |
| Ischaemic heart disease (I20–I25) | 19 (0.6) | 17 (0.6) | 22 (0.7) | 33 (1.1) |
| Other cardiac disease (I26–51) | 17 (0.6) | 33 (1.1) | 26 (0.9) | 30 (1.0) |
| Cerebrovascular disease (I60–69) | 44 (1.5) | 57 (1.9) | 51 (1.7) | 39 (1.3) |
| Other circulatory disease | 2 (0.1) | 1 (0.0) | 2 (0.1) | 1 (0.0) |
| Pulmonary disease (J00–J99) | 49 (1.6) | 41 (1.4) | 46 (1.5) | 63 (2.1) |
| Pneumonia and influenza (J10–29) | 24 (0.8) | 21 (0.7) | 28 (0.9) | 35 (1.2) |
| COPD and allied conditions (J40–47) | 12 (0.4) | 8 (0.3) | 7 (0.2) | 8 (0.3) |
| Other pulmonary disease | 13 (0.4) | 12 (0.4) | 11 (0.4) | 20 (0.7) |
| Lung cancer (C33–C34) | 23 (0.8) | 16 (0.5) | 27 (0.9) | 20 (0.7) |
| Other causes§ | 164 (5.5) | 146 (4.9) | 148 (4.9) | 95 (3.2) |
Participants were men and women aged 65 years or over living in the study areas in 1999.
↵* In the subsequent analyses, totally 12 029 participants were included after exclusion of those without a known cause of death and those who were lost to follow-up during 1999–2002.
↵† No. (%) of participants is shown. Death rates (%) are calculated by dividing the number of mortalities by the total number of participants in each category. Percentages may not sum to 100% due to rounding.
↵‡ Body mass index is calculated as body weight (kg) divided by height squared (m2).
↵§ Mortality from other causes is defined as deaths due to causes other than cardiopulmonary disease or lung cancer.
COPD, chronic obstructive pulmonary disease.