Decline in air pollution and change in prevalence in respiratory symptoms and chronic obstructive pulmonary disease in elderly women

Table 2 Prevalence of respiratory symptoms, chronic bronchitis at baseline (1985 - 1994) and at follow-up (2006) and COPD at baseline (1985-1994) and at follow-up (2007/2008) in a subgroup of elderly women

	Prevalence
	Baseline			Follow-up
Respiratory health outcome	all	Ruhr area	rural areas	all	Ruhr area	rural areas
Chronic Bronchitis by physician's diagnosis ^a	N = 2073 (8.2%)	N = 1167 (9.3%)	N = 905 (6.6%)	N = 2032 (11.6%)	N = 1125 (13.6%)	N = 90782 (9.0%)
Chronic cough ^a	N = 2110 (20.6%)	N = 1175 (22.7%)	N = 935 (18.0%)	N = 1947 (26.5)	N = 1079 (27.9%)	N = 868 (24.7%)
Chronic cough with phlegm production ^a	N = 2099 (9.5%)	N = 1168 10.1%	N = 931 8,8%	N = 1979 (13.3%)	N = 1098 (13.5%)	N = 890 (13.2%)
Mild COPD ^b FEV ₁ /FVC < 0.7	N = 384 (8.6%)	N = 201 10.5%	N = 183 6.6%	N = 347 (18.2%)	N = 179 (12.9%)	N = 163 (22.7%)
Moderate COPD ^b FEV ₁ /FVC< 0.7 and FEV ₁ < 80% predicted	N = 384 (3.7%)	N = 201 5.0%	N = 183 2.2%	N = 347 (6.6%)	N = 179 (5.6%)	N = 163 (8.0%)

^aReported by participant
^bOnly in a subgroup that was invited for the follow-up examination in 2007/2008. Women with asthma were excluded

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