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Asthma Research and Practice

, 3:6

First Online: 01 August 2017Received: 27 September 2016Accepted: 19 July 2017


BackgroundMany studies have evaluated associations between asthma emergency department ED visits, hospital admissions HAs, and ambient ozone O3 across the US, but not in Texas. We investigated the relationship between O3 and asthma HAs, and the potential impacts of outdoor pollen, respiratory infection HAs, and the start of the school year in Texas.

MethodsWe obtained daily time-series data on asthma HAs and ambient O3 concentrations for Dallas, Houston, and Austin, Texas for the years 2003–2011. Relative risks RRs and 95% confidence intervals CIs of asthma HAs per 10-ppb increase in 8-h maximum O3 concentrations were estimated from Poisson generalized additive models and adjusted for temporal trends, meteorological factors, pollen, respiratory infection HAs, day of the week, and public holidays. We conducted a number of sensitivity analyses to assess model specification.

ResultsWe observed weak associations between total asthma HAs and O3 at lags of 1 day RR10 ppb = 1.012, 95% CI: 1.004–1.021, 2 days RR10 ppb = 1.011, 95% CI: 1.002–1.019, and 0–3 days RR10 ppb = 1.017, 95% CI: 1.005–1.030. The associations were primarily observed in children aged 5–14 years e.g., for O3 at lag 0–3 days, RR10 ppb = 1.037, 95% CI: 1.011–1.064, and null in individuals 15 years or older. The effect estimates did not change significantly with adjustment for pollen and respiratory infections, but they attenuated considerably and lost statistical significance when August and September data were excluded. A significant interaction between time around the start of the school year and O3 at lag 2 day was observed, with the associations with pediatric asthma HAs stronger in August and September RR10 ppb = 1.040, 95% CI: 1.012–1.069 than in the rest of the year October–July RR10 ppb = 1.006, 95% CI: 0.986–1.026.

ConclusionsWe observed small but statistically significant positive associations between total and pediatric asthma HAs and short-term O3 exposure in Texas, especially in August and September. Further research is needed to determine how the start of school could modify the observed association between O3 and pediatric asthma HAs.

KeywordsOzone Air pollution Asthma hospital admissions Epidemiology Time series AbbreviationsAAAAIAmerican Academy of Allergy, Asthma and Immunology

CIConfidence Interval

EDEmergency Department

FEV1Forced Expiratory Volume in One Second

FVCForced Vital Capacity

HAHospital Admission

ICD-9International Classification of Disease, 9th Revision

IRBInstitutional Review Board

NAAQSNational Ambient Air Quality Standard

NABNational Allergen Bureau


PpbParts Per Billion

RRRelative Risk

SDStandard Deviation

TCEQTexas Commission on Environmental Quality

TDSHSTexas Department of State Health Services

USUnited States

Electronic supplementary materialThe online version of this article doi:10.1186-s40733-017-0034-1 contains supplementary material, which is available to authorized users.

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Autor: Julie E. Goodman - Ke Zu - Christine T. Loftus - Ge Tao - Xiaobin Liu - Sabine Lange


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