TABLE 4.
SENSITIVITY ANALYSES: RATE RATIOS AND 95% CONFIDENCE INTERVALS FOR INTERQUARTILE RANGE INCREASES IN THREE-DAY MOVING AVERAGE POPULATION-WEIGHTED AMBIENT AIR POLLUTANT CONCENTRATIONS
| Alternative Model Specifications |
||||||
|---|---|---|---|---|---|---|
| Base Model* RR (95% CI) | No URI Control† RR (95% CI) | Time-series‡ RR (95% CI) | Case-crossover§ RR (95% CI) | Bi-monthly windows‖ RR (95% CI) | Lag -1 Pollution¶ RR (95% CI) | |
| Warm season (May–October) | ||||||
| Ozone | 1.082 (1.043–1.123) | 1.106 (1.066–1.147) | 1.071 (1.025–1.119) | 1.092 (1.049–1.137) | 1.058 (1.014–1.104) | 1.015 (0.991–1.039) |
| Nitrogen dioxide | 1.066 (1.038–1.095) | 1.073 (1.045–1.102) | 1.058 (1.028–1.088) | 1.096 (1.065–1.127) | 1.065 (1.034–1.098) | 1.000 (0.981–1.019) |
| Carbon monoxide | 1.068 (1.034–1.102) | 1.073 (1.039–1.107) | 1.062 (1.030–1.096) | 1.090 (1.054–1.127) | 1.053 (1.016–1.092) | 1.009 (0.988–1.031) |
| Sulfur dioxide | 1.030 (1.002–1.058) | 1.033 (1.006–1.062) | 1.021 (0.992–1.051) | 1.009 (0.981–1.039) | 1.014 (0.984–1.046) | 1.007 (0.990–1.025) |
| PM10 | 1.026 (1.001–1.051) | 1.043 (1.018–1.068) | 1.031 (1.005–1.058) | 1.057 (1.030–1.085) | 1.022 (0.994–1.050) | 1.024 (1.005–1.043) |
| PM10–2.5 | 1.025 (0.991–1.059) | 1.032 (0.998–1.067) | 1.028 (0.992–1.065) | 1.062 (1.026–1.099) | 0.984 (0.945–1.024) | 1.004 (0.983–1.025) |
| PM2.5 | 1.043 (1.016–1.070) | 1.060 (1.033–1.088) | 1.041 (1.012–1.071) | 1.043 (1.015–1.072) | 1.015 (0.984–1.046) | 1.024 (1.004–1.045) |
| PM2.5 sulfate | 1.027 (1.004–1.049) | 1.040 (1.017–1.063) | 1.025 (1.002–1.048) | 1.024 (1.000–1.047) | 1.003 (0.977–1.029) | 1.017 (1.001–1.034) |
| PM2.5 elemental carbon | 1.041 (1.010–1.072) | 1.051 (1.020–1.083) | 1.032 (1.000–1.065) | 1.057 (1.024–1.090) | 1.036 (0.984–1.091) | 1.000 (0.979–1.020) |
| PM2.5 organic carbon | 1.034 (1.007–1.062) | 1.047 (1.020–1.075) | 1.036 (1.005–1.067) | 1.050 (1.021–1.079) | 1.019 (0.987–1.052) | 1.000 (0.982–1.018) |
| PM2.5 water-soluble metals | 1.029 (1.003–1.055) | 1.039 (1.013–1.065) | 1.021 (0.996–1.047) | 1.030 (1.004–1.057) | 1.015 (0.986–1.045) | 0.992 (0.976–1.009) |
| Cold season (November–April) | ||||||
| Ozone | 1.044 (0.992–1.098) | 1.062 (1.010–1.118) | 1.013 (0.953–1.077) | 1.053 (0.996–1.113) | 1.019 (0.961–1.080) | 1.004 (0.973–1.036) |
| Nitrogen dioxide | 1.016 (0.992–1.040) | 1.023 (1.000–1.048) | 1.007 (0.982–1.033) | 1.020 (0.994–1.047) | 1.022 (0.995–1.050) | 0.999 (0.983–1.014) |
| Carbon monoxide | 1.005 (0.985–1.025) | 1.017 (0.997–1.037) | 1.002 (0.982–1.023) | 1.003 (0.981–1.025) | 1.005 (0.982–1.028) | 0.999 (0.986–1.012) |
| Sulfur dioxide | 1.001 (0.978–1.025) | 1.000 (0.977–1.024) | 1.009 (0.984–1.034) | 0.999 (0.975–1.025) | 1.014 (0.988–1.040) | 1.003 (0.990–1.017) |
| PM10 | 1.018 (0.994–1.043) | 1.026 (1.001–1.051) | 1.009 (0.983–1.035) | 1.033 (1.006–1.061) | 1.020 (0.992–1.049) | 0.995 (0.976–1.014) |
| PM10–2.5 | 1.041 (1.010–1.073) | 1.036 (1.006–1.068) | 1.018 (0.985–1.052) | 1.073 (1.041–1.107) | 1.042 (1.004–1.080) | 1.001 (0.981–1.020) |
| PM2.5 | 1.005 (0.978–1.031) | 0.995 (0.969–1.022) | 0.999 (0.971–1.028) | 1.027 (0.998–1.056) | 1.012 (0.982–1.044) | 0.982 (0.961–1.003) |
| PM2.5 sulfate | 0.991 (0.953–1.029) | 0.976 (0.939–1.014) | 0.980 (0.941–1.022) | 1.026 (0.983–1.070) | 1.012 (0.968–1.059) | 0.971 (0.943–1.000) |
| PM2.5 elemental carbon | 1.003 (0.981–1.026) | 1.005 (0.983–1.028) | 0.998 (0.974–1.022) | 1.014 (0.992–1.037) | 1.004 (0.979–1.030) | 0.996 (0.981–1.012) |
| PM2.5 organic carbon | 1.000 (0.985–1.016) | 0.999 (0.984–1.015) | 0.998 (0.981–1.105) | 1.007 (0.992–1.023) | 1.002 (0.985–1.020) | 0.994 (0.983–1.010) |
| PM2.5 water-soluble metals | 1.005 (0.968–1.043) | 1.004 (0.967–1.043) | 0.985 (0.949–1.023) | 1.017 (0.978–1.058) | 0.994 (0.949–1.042) | 0.998 (0.974–1.023) |
Definition of abbreviations: CI = confidence interval; PM = particulate matter less than 10, 2.5, or 10–2.5 μm in aerodynamic diameter; RR = rate ratio; URI = upper respiratory infections.
Bold typeface indicates confidence intervals that do not include the null value.
The “base model” is the primary statistical model as described in the Methods section. The results in this column are reproduced from Table 2.
Model is identical to the base model, except there is no control for pediatric emergency department visits for upper respiratory infections.
Model is does not contain terms for year, month, month × year interactions, month × lag 0 maximum temperature interactions, and month × day-of-week interactions. Instead cubic splines with monthly knots are included to control for long-term and seasonal trends. Daily average temperature and dew point were modeled using cubic splines with knots at the 25th and 75th percentiles. These models are analogous to those presented in earlier publications (14, 18, 20, 31).
Model contains three-way interactions between year, month, and day-of-week and does not contain month × lag 0 maximum temperature interactions.
Model is identical to the base model, except that bimonthly (twice-per-month) indicator variables are used instead of monthly indicator variables.
Model is identical to the base model, save for the addition of tomorrow's (lag -1) pollutant concentration, which has been included in the model. The results in this column are the rate ratios estimated for the lag -1 term.