Table 6

Further investigation of associations with PEF exacerbations and dyspnoea: single and multiple pollutant models*

Model^*	Single pollutant models			Multiple pollutant models
Model^*	OR^† (unit change)	SE	p Value	OR^† (unit change)	SE	p Value	OR^‡ (IQR change)
Symptomatic fall in PEF (N=78)
Model 1
NO₂	1.004	0.003	0.137	0.999	0.003	0.709	0.983
PM₁₀	1.006	0.003	0.029	1.007	0.003	0.042	1.140
Model 2
NO₂	1.004	0.003	0.137	1.002	0.004	0.654	1.025
Black smoke	1.007	0.004	0.050	1.005	0.005	0.306	1.049
Model 3
PM₁₀	1.006	0.003	0.029	1.006	0.004	0.083	1.126
Black smoke	1.007	0.004	0.050	1.000	0.005	0.953	0.998
Model 4
NO₂	1.004	0.003	0.137	0.999	0.004	0.725	0.980
PM₁₀	1.006	0.003	0.029	1.007	0.004	0.064	1.137
Black smoke	1.007	0.004	0.050	1.001	0.006	0.907	1.006
Dyspnoea n=77
Model 1
NO₂	1.003	0.003	0.338	0.997	0.003	0.380	1.017
PM₁₀	1.006	0.002	0.008	1.008	0.003	0.007	1.031
Model 2
NO₂	1.003	0.003	0.338	1.001	0.004	0.760	0.961
Black smoke	1.003	0.005	0.526	1.003	0.006	0.598	1.159
Model 3
PM₁₀	1.006	0.002	0.008	1.008	0.003	0.007	1.156
Black smoke	1.003	0.005	0.526	0.996	0.006	0.455	0.961
Model 4
NO₂	1.003	0.003	0.338	0.998	0.004	0.578	0.970
PM₁₀	1.006	0.002	0.008	1.008	0.003	0.005	1.168
Black smoke	1.003	0.005	0.526	0.998	0.007	0.733	0.979

↵* In addition to individual pollutants (previous day), each model includes outdoor temperature (average of the min and maximum) and season (four categories) plus control for autocorrelation. Models 1–3 each contain two pollutants analysed together. Model 4 includes all three pollutants.
↵† ORs are for a 1 unit change in pollution level (ppb for NO₂, O₃, SO₂; μg/m³ for PM₁₀, black smoke).
↵‡ ORs are for an IQR change in pollutant level.
PEF, peak expiratory flow; PM, particulate matter.