Table 3.

Estimated increase in the daily number of deaths for all ages associated with an increase of 10 µg/m³ of O₃ concentrations (average of lags 0 and 1) at the 25th and 75th percentile of the center-specific distribution of selected effect modifiers

	US			Europe			Canada
	25 %	75 %	t-value	25 %	75 %	t-value	25 %	75 %	t-value
NO2 coefficient variation	0.156	0.010	−2.870	0.210	0.170	−0.485	0.394	0.502	1.328
Mean SO2	0.058	0.253	2.785	0.195	0.209	0.157	0.285	0.594	2.156
O3 coefficient variation	0.024	0.185	2.683	0.330	0.142	−2.647	0.364	0.441	0.597
Mean NO2/PM10	−0.007	0.159	2.639	0.224	0.192	−0.429	0.488	0.320	−1.582
Mean temperature	0.269	0.001	−4.398	0.203	0.199	−0.040	0.356	0.445	0.831
% ≥75 year	0.132	0.132	−0.022	0.190	0.229	0.518	0.276	0.535	2.680
Age-standardized mortality	−0.136	0.138	3.811	0.143	0.254	1.073	0.330	0.505	1.137
% Unemployed	0.023	0.191	2.454	0.176	0.167	−0.068	0.347	0.467	1.877

The variables shown displayed significant effect modification in at least four out of eight models applied in at least one center (i.e., Canada, Europe, the US)

O₃ ozone, NO₂ nitrogen dioxide, SO₂ sulfur dioxide, PM₁₀ particulate matter <10 µm aerodynamic diameter