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Table 5 Relative risks of pediatric asthma HAs (5–14 years) per 10-ppb increase in daily 8-h maximum O3 concentrations, stratified by time period, with adjustments for pollen and respiratory infections, in Dallas, Houston, and Austin, Texas from 2003 to 2011

From: Ambient ozone and asthma hospital admissions in Texas: a time-series analysis

O3 concentrations

Model 1a

Model 2b

Model 3c

Full year

Full year

August–September

October–July

Same day

1.023

(1.004–1.043)

1.023

(1.004–1.043)

1.036

(1.007–1.066)

1.017

(0.995–1.039)

Pinteraction = 0.24

Lag 1 day

1.022

(1.004–1.040)

1.021

(1.003–1.040)

1.025

(0.997–1.054)

1.020

(0.999–1.041)

Pinteraction = 0.75

Lag 2 day

1.016

(0.998–1.034)

1.016

(0.998–1.034)

1.040

(1.012–1.069)

1.006

(0.986–1.026)

Pinteraction = 0.03

Lag 0–3 days

1.031

(1.005–1.058)

1.031

(1.005–1.057)

1.053

(1.015–1.093)

1.020

(0.991–1.050)

Pinteraction = 0.12

  1. HA hospital admission, ppb parts per billion, SD standard deviation, O 3 ozone
  2. aModel 1 adjusted for cubic splines of calendar time (8 d.f. per year), cubic splines of same-day temperature (3 d.f.), cubic splines of the average of lag 1 through 3 day temperature (3 d.f.), cubic splines of same-day dew point (3 d.f.), cubic splines of the average of lag 1 through 3 day dew point (3 d.f.), day of the week, public holidays, total pollen counts (lag 0–2 days, categorical), and total respiratory infection HAs (lag 0–2 days, cubic splines with 3 d.f.)
  3. bModel 2 was Model 1 with additional adjustment for the start of school year (indicator variable for August/September)
  4. cModel 3 was Model 1 with additional adjustment for the start of school year (indicator variable for August/September) and the interaction between the start of school year and ambient O3 concentrations