Table 4.
RRs (95% CI) and P Values in Associations Between 10 μg/m3 Increments of PM2.5 Concentrations and PVC Counts in First‐Degree and Third‐Degree Polynomial Distributed Lag Models
| First‐degree model* | Third‐degree model† | |||
|---|---|---|---|---|
| RR (95% CI) | P value | RR (95% CI) | P value | |
| Lag 0, instantaneous | 1.003 (0.997, 1.016) | 0.68 | 0.994 (0.981, 1.008) | 0.42 |
| Lag 1, 0.5–1.0 h prior | 1.009 (0.997, 1.022) | 0.13 | 1.025 (1.008, 1.042) | <0.01 |
| Lag 2, 1.0–1.5 h prior | 1.016 (1.004, 1.028) | <0.01 | 1.013 (1.003, 1.023) | 0.01 |
| Lag 3, 1.5–2.0 h prior | 1.023 (1.004, 1.035) | 0.02 | 1.018 (1.001, 1.035) | 0.04 |
| Cumulative, within 2.0 h | 1.052 (1.003, 1.103) | 0.04 | 1.050 (1.002, 1.101) | 0.04 |
All models were adjusted for age, race, sex, body mass index percentile, temperature, and relative humidity. PM2.5 indicates fine particles with aerodynamic diameters ≤2.5 μm; PVC, premature ventricular contraction; and RR, rate ratio.
*
In the first‐degree model, P values for zero‐ and first‐degree polynomials were 0.68 and <0.01, respectively.
†
In the third‐degree model, P values for zero‐, first‐, second‐, and third‐degree polynomials were 0.42, <0.01, 0.04, and 0.17, respectively.