Finally, we assessed the inclusion of potential intermediate variables, co-morbidities, and use of different lags for daily temperature and NO2 levels before examination (lags: 1, 2, 3, and the average from 0too 3 days), compared with lag 0 (used by default).
In Fig. 2, we graph the average call rate for each distinct temperature value as a function of temperature at different lags ranging from 0 34.
Second, where the PSSM matrix was subjected to auto-cross covariance (ACC) transformation (for details consult Dong et al. [35]) at different lags lg varying from 5 to 40.
To examine the temporal relationship of PM2.5 constituents with mortality, we fitted the models with different lag structures from 0 lag days to 3 lag days because our previous work on PM2.5 and daily mortality in China showed little evidence of a significant association with a lag beyond 3 days (Kan et al. 2007; Ma et al. 2011).
For the linear approximation of rainfall models, the 75 and 95% cut-off points were chosen, corresponding with 3 mm and 34 mm rainfall for lag 0. Associations between rainfall at different lags and mortality were weak – only lag 0 3 rainfall deviated from the other presented models (see Fig. 4).
Schwartz et al. (2008) provide an example from air pollution where a five-knot linear spline model was used with different lags on pollution exposure.
The association between the outcome and each independent variable was measured separately and at different time lags (from −14 days to +14 days).
Furthermore, results of sensitivity analyses based on alternative results (e.g., using different exposure lags) from the individual studies, and inclusion of data from a study of potash miners (Mohner et al. 2013), which ranged from lnRR 0.00061 to 0.0011 for a 1-μg/m-year increase in EC, were not substantially different from our main estimate of 0.00098 (95% CI: 0.00055, 0.00141).
The different lag associations ranging from an immediate F eNO response to the preceding 5 hr of PM2.5 to 2-day average PM2.5 also suggest different sources and varying biologic mechanisms are at play.
We also calculated different lag time exposure windows from recruitment date using residential and Milan monitors.
