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

Abstract

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

Benefits of influenza vaccination on the associations between ambient air pollution and allergic respiratory diseases in children and adolescents: New insights from the Seven Northeastern Cities study in China

“…The independent effects of air pollution or influenza vaccination on childhood allergic respiratory diseases have been extensively investigated (Dong et al 2011;Goodman et al 2017;Herbert et al 2017;Ray et al 2017;Yang et al 2018). However, few studies have investigated potential effect modification by vaccination for high risk populations.…”

Assessing the impact of air pollution on childhood asthma morbidity: how, when, and what to do

“…Exposure to air pollutants has been consistently linked with poor asthma control in children, with numerous studies showing reduced lung function (2**–7**)(Table 1) and increased rates of rescue medication use, emergency department visits, and hospitalizations for asthma exacerbation (8*–13)(Table 2). In this section, we discuss the most recent evidence for the effects of air pollutants on pediatric asthma.…”

“…Nitrogen oxides and volatile organic compounds react in the presence of sunlight to generate ozone (O 3 ), a by-product of photochemical smog. Both acute and long term exposure to O 3 is associated with negative pulmonary health effects including lower FEV 1 /FVC ratio (4*), increased asthma-related ED visits (30, 33) and hospital admissions (13), and more severe asthma exacerbations (9). Short term O 3 exposures during the months of August and September were positively associated with hospital admission for asthma among children 5–14 years in Texas, even after controlling for pollen and viral infections (13).…”

“…Both acute and long term exposure to O 3 is associated with negative pulmonary health effects including lower FEV 1 /FVC ratio (4*), increased asthma-related ED visits (30, 33) and hospital admissions (13), and more severe asthma exacerbations (9). Short term O 3 exposures during the months of August and September were positively associated with hospital admission for asthma among children 5–14 years in Texas, even after controlling for pollen and viral infections (13). Children are particularly susceptible, with a nearly 10% increase in risk of ED visits for asthma for each interquartile range (IQR) increase in O 3 , with the largest effect found in 6–19 year olds (33).…”

Relationship between exposure to ozone and exacerbation requiring hospital admission among patients with asthma: a case-control study in central Taiwan

“…Accumulating pieces of evidence have shown that exposure to O 3 correlated with exacerbation of asthma. [8][9][10] Goodman et al investigated the effects of O 3 on asthma exacerbation in Texas and found a positive association between increased O 3 exposure and hospital admission due to asthma in patients aged 5-14 years. 9 Sacks et al, using a time-stratified case-crossover study in North Carolina, also reported a positive association between O 3 and asthma-associated emergency department visits in children (5-17 years of age).…”