The impact of outdoor air quality on respiratory and cardiovascular health is well established.^1–5 Exposure to ambient air pollution affects asthma,⁶ school absences because of asthma,⁷ emergency department visits and hospital admissions for respiratory and cardiovascular diseases,^5,8,9 and cardiopulmonary mortality.^10–13 Information about air quality and its associated health risks is communicated to the public using air quality alerts, such as the U.S. Environmental Protection Agency’s Air Quality Index.¹⁴ The Air Quality Index is a six-category index that uses daily and local measurements of air pollutants to identify air quality conditions that range from good, when air quality poses little or no health risk, to hazardous, when air quality is likely to cause serious health effects.^14,15 Air quality alerts, such as the Air Quality Index, are used to inform the public when air quality is likely to affect sensitive populations, including people with heart or lung disease.¹⁵

Broadly speaking, the effectiveness of air quality alerts depends on the extent to which individuals in sensitive populations are aware of the alerts and take action to reduce their exposures to poor air quality. Estimates of the proportion of the populations aware of air quality alerts range from one third in the general population¹⁶ to 95% among parents seeking care for a child with asthma.¹⁷ By contrast, only small fractions of the population report changing behaviors during episodes of poor air quality.^18,19 For example, data from the National Health and Nutrition Survey Examination indicate that 12% of adults reported doing something differently (e.g., spending less time outdoors, closing windows) because of poor air quality.¹⁸ Older adults, women, those with more education, and adults with respiratory or cardiovascular conditions were more likely report such an activity change.¹⁸ However, findings from qualitative research indicate that individuals with asthma or cardiovascular disease do not necessarily change their behaviors in response to air quality alerts (Scott A. Damon, unpublished observations, 2016).

Because of the well-recognized impact of air pollution on the health of individuals with pre-existing respiratory and heart disease, there is a need to better understand awareness of air quality alerts and specific actions taken, especially by at-risk individuals, to reduce air pollution exposure. The aim of this study is to assess associations of respiratory and heart disease with awareness of air quality alerts, discussing, with a health professional strategies to reduce air pollution exposure, and avoiding busy roads to reduce air pollution exposure.

Data from the summer 2014–2016 waves of the ConsumerStyles surveys conducted by the public relations firm Porter Novelli Public Services were used. Each year, ConsumerStyles surveys are conducted as cross-sectional surveys of a random sample of adults from KnowledgePanel^®, an Internet panel of ≅55,000 men and women aged ≥18 years. Sampling is probability-based to be representative of the U.S. adult population. Additional details about the survey are available elsewhere.^20–22 From 2014 through 2016, the summer waves of the ConsumerStyles surveys (hereafter referred to as SummerStyles) were conducted among the sample of adults who responded to the spring waves of the ConsumerStyles surveys (i.e., SpringStyles). Analysis of ConsumerStyles data is exempt from IRB review at the Centers for Disease Control and Prevention.

Demographic characteristics and respiratory and heart disease status of the respondents are shown in Table 1. The average age of respondents was 46.8 years (SD=17.4 years, range, 18–94 years). Overall, 6.9% reported having asthma, 2.3% reported having emphysema/COPD, and 3.4% reported having heart disease. There was little overlap between the three conditions, with 0.7% of the population (n=95) reporting asthma and emphysema/COPD, 0.5% (n=48) reporting asthma and heart disease, and 0.6% (n=73) reporting emphysema/COPD and heart disease. Of the 12,599 respondents, 49.2% were aware of air quality alerts where they live, 3.0% had discussed with a health professional strategies to reduce air pollution exposure, and 27.3% always/usually avoided busy roads to reduce their air pollution exposure when walking, biking, or exercising outdoors.

The percentage of adults aware of air quality alerts increased with increasing age and educational attainment and was highest among white, non-Hispanic respondents (54.9%, 95% CI=53.7, 56.1), higher among men than women (52.6%, 95% CI=51.1, 54.1 vs 46.0%, 95% CI=44.6, 47.4, respectively), and higher among former smokers (52.3%, 95% CI=50.5, 54.2) and lifetime non-smokers (49.1%, 95% CI=47.7, 50.5) than current smokers (43.5%, 95% CI=40.7, 46.2; Table 2). The percentage of adults who reported always/usually avoiding busy roads to reduce air pollution exposure generally followed similar patterns across categories of age and smoking status; however, more variation was observed across categories of educational attainment and race/ethnicity and the percentage was higher among women than men. The numbers of respondents who discussed with a health professional strategies to reduce air pollution exposure were low and no clear patterns were identified in the percentages across demographic categories.

Weighted percentages reporting the three aspects of air quality awareness and unadjusted PRs are shown in Table 3. In adjusted models, asthma was associated with increased prevalence of awareness of air quality alerts (PR=1.11, 95% CI=1.04, 1.20), discussing with a health professional strategies to reduce air pollution exposure (PR=4.88, 95% CI=3.74, 6.37), and always/usually avoiding busy roads to reduce air pollution exposure (PR=1.13, 95% CI=1.01, 1.27; Table 4). Emphysema/COPD was positively associated with discussing with a health professional strategies to reduce air pollution exposure (PR=3.31, 95% CI=2.21, 4.95). Heart disease was not associated with awareness of air quality alerts, discussing with a health professional strategies to reduce air pollution exposure, or always/usually avoiding busy roads to reduce air pollution exposure. Heart disease was, however, positively associated with never avoiding busy roads to reduce air pollution exposure (PR=1.14, 95% CI=1.03, 1.27).

These data show that awareness of air quality alerts, discussing with a health professional strategies to reduce air pollution exposure, and taking action to reduce air pollution exposure by avoiding physical activity on busy roads are more common among adults with respiratory diseases than among adults without respiratory diseases. These findings support existing evidence that adults with asthma are not only more aware of, but also more likely to change their outdoor activities because of, media alerts about air quality than adults without asthma.¹⁹ In this study, emphysema/COPD was positively associated with discussing with a health professional strategies to reduce air pollution exposure, whereas heart disease was only associated with never avoiding busy roads to reduce air pollution exposure. Taken together, these findings broaden the available information about the extent to which targeting messages about air quality may raise awareness about air quality alerts and motivate behavior changes to reduce air pollution exposure among adults at risk of exacerbations during periods of unhealthy air quality.

The SummerStyles data are weighted to reflect the U.S. population of adults and the weighted prevalences of asthma (6.9%) and heart disease (3.4%) reported from these data are similar to estimates of these conditions from other nationally representative data sources. In 2015, for example, among U.S. adults aged 18 years and older, the prevalence of asthma was estimated to be 7.6%²³ and the prevalence of coronary heart disease was estimated to be 3.7%.²⁴ Regarding air quality awareness, weighted results indicate that 49% of the U.S. population of adults are aware of air quality alerts where they live, 3% have discussed with a healthcare professional strategies to reduce air pollution exposure, and 27% always/usually avoid busy roads to reduce air pollution exposure when walking, biking, or exercising outdoors. Previous epidemiologic research reveals distinct challenges involved in using air quality alerts to trigger changes in behavior. In 2008, Semenza et al.¹⁶ reported that air quality alerts were not effective in changing adults’ behaviors and that when behavior changes did occur they were more often motivated by perceptions of poor air quality than by air quality alerts. The observed variations in awareness of air quality alerts and avoiding busy roads to reduce air pollution exposure across categories of age, educational attainment, and other demographic traits, as well as across categories of health status, suggest that targeted interventions might improve awareness of air quality alerts and willingness to make changes during periods of poor air quality.

These analyses include data collected over 3 years. Increases from 2014 to 2016 in percentages of the entire population that were aware of air quality alerts and that always/usually avoided busy roads to reduce air pollution exposure were modest and not statistically significant at α=0.05 (data not shown), but nonetheless suggest increases over time toward more air quality awareness. By contrast, the low percentages and minimal variation across demographic characteristics and over time in discussing with a health professional strategies to reduce air pollution exposure (data not shown) suggest that interventions aimed at increasing knowledge and changing behaviors among health professionals are warranted.

For these analyses, data collected over three cycles of SummerStyles surveys were pooled together. This analytic decision increased the size of the analytic sample, decreased the magnitudes of the errors associated with estimates of prevalence, and eased interpretation of the results by presenting a single result for each exposure–outcome association. Indeed, there was little variation in the estimates across the 3 years; however, this analytic approach precludes presenting results that provide information about trends in air quality awareness over time. Similarly, because these analyses included data pooled from 3 survey years, respondents who completed the survey in 2 or more years were included in the final population more than once. As a result, responses provided by the 1,658 (16%) respondents who participated in two of the three surveys and the 380 (4%) who participated all 3 years are not independent. Because the data were weighted to reflect the distribution of the U.S. population on nine individual- and household-level factors, duplicate respondents could not be removed while preserving the representativeness of the sample. Examining correlations in responses provided by those who participated in 2 years revealed higher correlations between repeated questions about health status (asthma: ρ=0.77; emphysema/COPD: ρ=0.72; heart disease: ρ=0.56) than between repeated questions about air quality awareness (awareness of air quality alerts: ρ=0.47; discussing with a health professional: ρ=0.23; avoiding busy: ρ=0.43). The correlation coefficients for air quality awareness responses do not suggest that these findings are affected by highly correlated data, but do suggest that air quality awareness varies over time. Efforts to improve air quality awareness among sensitive populations likely need to include periodic or ongoing public health messages, rather than a one-time message.

For this study, heart disease was defined using responses to questionnaire items about having atrial fibrillation, congestive heart failure, and other heart disease. Ideally, a broad definition of heart disease would also include having a history of coronary artery disease, bypass surgery or angioplasty, an internal cardiac defibrillator, a stroke or transient ischemic attack, and blockages in the arteries of the neck and legs. Collectively, these conditions represent those with known heart disease who are at risk of adverse outcomes because of poor air quality. Because these conditions were not included in the questionnaire, the findings presented might not be representative of air quality awareness in the population with these other aspects of heart disease. Nonetheless, these results—in particular, the finding that heart disease was associated with never avoiding busy roads to reduce air pollution exposure—highlight an opportunity for raising awareness about air quality and its potential health effects among people with known heart disease.

These findings reveal important opportunities for preventing exacerbations among adults with respiratory and heart disease. For example, efforts to improve asthma control could include increasing awareness about air quality, air quality alerts, the health impacts of exposure to poor air quality, and changes in behaviors that may reduce exposures during episodes of poor air quality. Similarly, Million Hearts^®, a national initiative to prevent one million heart attacks and strokes over 5 years, provides an opportunity to increase air quality awareness among people with heart disease. Messages raising awareness about the impact of poor air quality on people with known heart disease, how to receive air quality alerts, and how to change behaviors based on alerts, can be disseminated repeatedly through the initiative’s robust social media channels, e-newsletters, and patient materials. Million Hearts can also activate clinical partners and health advocates to equip clinicians with tools that address these issues.

In this study, existing respiratory disease, but not heart disease, was associated with increased air quality awareness. In conjunction with the current understanding of the mechanisms by which air pollution exposures exacerbate existing disease among adults with asthma, COPD, and heart disease,^2,3,25 and affect respiratory and cardiovascular mortality globally,²⁶ these findings reveal opportunities to raise awareness about air quality alerts and behavior changes aimed at reducing air pollution exposure during periods of unhealthy air quality.