Table 2

Effects of Air Pollution and Other Environmental Exposures on Estimates of Severe Influenza Illness, Washington, USA

Ranjani Somayaji, Moni B. Neradilek, Adam A. Szpiro, Kathryn H. Lofy, Michael L. Jackson, Christopher H. Goss, Jeffrey S. Duchin, Kathleen M. Neuzil, and Justin R. Ortiz

Author affiliations: University of Calgary, Calgary, Alberta, Canada (R. Somayaji); University of Washington, Seattle, Washington, USA (R. Somayaji, A.A. Szpiro, C.H. Goss, J.S. Duchin); The Mountain-Whisper-Light Statistics, Seattle (M.B. Neradilek); Washington State Department of Health, Shoreline, Washington, USA (K.H. Lofy); Kaiser Permanente Washington Health Research Institute, Seattle (M.L. Jackson); Seattle & King County Public Health, Seattle (J.S. Duchin); University of Maryland School of Medicine, Baltimore, Maryland, USA (K.M. Neuzil, J.R. Ortiz)

Main Article

Population attributable risk of influenza-associated respiratory and circulatory hospitalizations by age group modeled with and without environmental covariates, October 2001–December 2012

Model type	Age group
Model type	0–6 mo	7–23 mo	2–4 y	5–14 y	15–49 y	50–64 y	≥65 y
Without environmental covariates*
All influenza, %	2.0 (0.6–3.4)	0.8 (−0.8 to 2.3)	2.0 (0.6–3.4)	4.8 (3.7–6.0)	0.8 (0.3–1.1)	0.6 (0.2–1.0)	0.7 (0.4–1.0)
Influenza A, %†	2.7 (1.4–4.0)	1.5 (0.2–2.9)	2.3 (1.0–3.5)	3.6 (2.5–4.7)	0.7 (0.3–1.0)	0.5 (0.1–0.8)	0.4 (0.1–0.6)
Influenza B, %	−0.7  (−1.6 to 0.2)	−0.8 (−1.6 to 0.1)	−0.2  (−1.1 to 0.6)	1.3  (0.7–1.9)	0.1  (−0.1 to 0.3)	0.1  (−0.1 to 0.3)	0.3  (0.1–0.5)
With environmental covariates*
All influenza, %	1.9 (0.5–3.3)	0.8 (−0.8 to 2.2)	2.0 (0.6–3.4)	4.8 (3.7–6.0)	0.7 (0.3–1.0)	0.5 (0.1–0.9)	0.6 (0.3–1.0)
Influenza A, %†	2.4 (1.2–3.7)	1.5 (0.1–2.9)	2.3 (1.0–3.5)	3.7 (2.6–4.8)	0.6 (0.2–0.9)	0.4 (0.0–0.8)	0.3 (−0.0 to 0.6)
Influenza B, %	−0.6 (−1.4 to 0.4)	−0.8 (−1.6 to 0.1)	−0.2 (−1.1 to 0.6)	1.2 (0.5–1.8)	0.1 (−0.1 to 0.3)	0.1 (−0.1 to 0.3)	0.3 (0.1–0.5)
Difference‡
All influenza	−0.1	0	0	0	−0.1	−0.1	−0.1
Influenza A†	−0.3	0	0	0.1	−0.1	−0.1	−0.1
Influenza B	0.1	0	0	−0.1	0	0	0

*Environmental covariates included daily averages of temperature, relative humidity, dew point, and particulate matter with a diameter <2.5 μm.
†We could not discern between influenza A(H3N2) and influenza A(H1N1) because of testing limitations over the study period.
‡With covariates minus without covariates.

Main Article

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