Air quality alerts benefit asthmatics
Authors: Kaylee Ho, Jeanette Paez, Bian Liu
Journal: The Lancet Planetary Health (2018)

We have read with interest the Article by Hong Chen and colleagues,1Chen H Li Q Kaufman JS et al.Effect of air quality alerts on human health: a regression discontinuity analysis in Toronto, Canada.Lancet Planet Health. 2018; 2: e19-e26Summary Full Text Full Text PDF PubMed Scopus (48) Google Scholar particularly the evidence of reductions in asthma-related emergency-department visits associated with air quality alert programmes in Toronto (ON, Canada). We have compared changes in activity between people with asthma and people who do not have asthma using representative data from the 2007–10 National Health and Nutrition Examination Survey in the USA.2Zipf G Chiappa M Porter KS Ostchega Y Lewis BG Dostal J National health and nutrition examination survey: plan and operations, 1999–2010.Vital Health Stat 1. 2013; 56: 1-37Google Scholar In our study, the self-reported response (Yes/No) to the question “During the past 12 months, when you thought or were informed air quality was bad, did you do anything differently?” was the outcome of interest. We differentiated asthma status into four groups according to the hierarchical survey questions: lifetime asthma (1864 of 13 419), current asthma (1071 of 13 376), defined as those who still had asthma at the time of the survey, those who had an asthma attack in the past year (515 of 1069), and those who had an asthma emergency department visit in the past year (718 of 1071). We excluded missing, refused, and unknown responses. We used survey logistic regression models to test the hypothesis that asthmatics were more likely to change activities compared with non-asthmatics, adjusting for age, race and ethnicity (non-Hispanic white, non-Hispanic black, Hispanic, and other), sex, and the ratio of family income to the poverty guidelines.3National Center for Health StatisticsSpecifying Weighting Parameters.https://www.cdc.gov/nchs/tutorials/Nhanes/SurveyDesign/Weighting/intro.htmDate: 2013Date accessed: December 20, 2017Google Scholar Overall, the survey-weighted proportion of individuals who changed their activity because of bad air quality between the asthmatic and non-asthmatics was 18·7% versus 10·3% for lifetime asthma, 23·1% versus 10·5% for current asthma, 25·3% versus 21·3% for asthma attack, and 22·9% versus 23·6% for asthma the emergency department visit groups. We found that the changes in activity were statistically significant in the lifetime asthma group (adjusted OR 1·9, 95% CI 1·7–2·2) and current asthma group (2·4, 2·0–2·8). The association was not significant for asthma emergency department visits (1·2, 0·8–1·9) or asthma attack (0·9, 0·6–1·4). Our results suggest that asthmatics are more likely to modify their activity than non-asthmatics when informed of poor air quality, which might help to prevent asthma exacerbation and avert emergency department visits. Despite the limitations of our analysis, which used a cross-sectional study design based on self-reported data, our finding, along with the evidence from Chen and colleagues, shows observable benefits of air quality alerts in lessening the burden of asthma, and highlights the fundamental role such programmes can play in public health protection. As governments worldwide have used air quality alert programmes as a public strategy to reduce adverse health outcomes, more research could be done to explore innovative programmes, such as personalised systems,4Samet JM Do air quality alerts benefit public health? New evidence from Canada.Lancet Planet Health. 2018; 2: e6-e7Summary Full Text Full Text PDF PubMed Scopus (2) Google Scholar and assess the effectiveness of these interventions on public health. We declare no competing interests. Effect of air quality alerts on human health: a regression discontinuity analysis in Toronto, CanadaIn this population-based cohort, the air quality alert programme was related to some reductions in respiratory morbidity, but not any other health outcome examined. This finding suggests that issuing air quality alerts alone has a limited effect on public health and that implementing enforced public actions to reduce air pollution on high pollution days could be warranted. Together with accumulating evidence of substantial burden from long-term air pollution exposure, this study underscores the need for further strengthening of global efforts that can lead to long-term improvement of overall air quality. Full-Text PDF Open AccessAir quality alerts benefit asthmatics – Authors' replyWe appreciate the comments by Kaylee Ho and colleagues1 on our study,2 in which we evaluated the influence of an air quality alert programme on a wide array of health outcomes in Toronto, Canada. The Correspondence by Ho and colleagues presented an analysis using the 2007–10 National Health and Nutrition Examination Survey in the USA, showing that individuals who had asthma were more likely to change their behaviours in response to deterioration in air quality than those without asthma.3 Their finding adds to the ongoing scientific discussion as to whether an air quality alert programme might encourage avoidance behaviours (eg, reducing outdoor travelling and physical activities) on days with high levels of pollution. Full-Text PDF Open Access