The risk of heart failure was higher in low- and middle-income countries when compared to high-income countries.
Both short- and long-term exposure to air pollution is associated with a significantly increased risk of heart failure (HF), according to a study published in Environmental Health Perspectives.
The research was conducted by analyzing 100 studies covering 20 countries that investigated the association between air pollutants—specifically PM2.5, PM10, NO2, SO2, CO, and O3—and HF hospitalization, incidence, or mortality, the investigators wrote.
The studies were split into a group analyzing short-term exposure if the interval between exposure and HF was 30 days or less, and another group analyzing long-term exposure if the interval was 1 year or greater, according to the study authors. The groups contained 81 and 19 studies, respectively.
For short-term exposure studies, 48 used a time-series analysis, 30 studies used a case-crossover analysis, 1 study used both of those analyses, and 2 cohort studies with survival analysis used the Cox proposition hazard risk model. For long-term exposure studies, all 19 used the cohort design, the study authors explained.
In the analysis of short-term exposure to air pollution, the study results showed a significant positive correlation with HF. A10μg/m3 increment of PM2.5 and PM10 was estimated to result in a 1.8% (RR = 1.018, 95% CI: 1.011, 1.025) and 1.6% (RR = 1.016, 95% CI: 1.011, 1.020) increase in the risk of HF hospitalization and mortality, respectively, according to the study results.
Notably, the risk of HF associated with each of the pollutants was higher in low- and middle-income countries (LMICs) when compared to high-income countries. Further, compared with Europe and North America, adverse impacts of pollutants on HF were generally larger in Asia, the study investigators found.
Among the 19 cohort studies analyzing long-term exposure to air pollutants, 14 of them assessed associations for PM2.5, 8 for PM10, 10 for NO2, 5 for O3, 3 for CO, and 2 for SO2. A10μg/m3 increment in PM2.5 and PM10 was associated with a 74.8% (RR = 1.748, 95% CI: 1.112, 2.747) and 21.2% (RR = 1.212, 95% CI: 1.010, 1.454) increased overall risk of HF, respectively, the results of the study show.
Further, the study found that a 10-ppb increment in NO2 was also associated with a 20.4% (RR = 1.204, 95% CI: 1.069, 1.356) higher risk of HF, while neither CO nor O3 was significantly related to the outcome of HF. The study authors wrote that an assessment of all 81 short-term exposure and 19 long-term exposure studies showed a low risk of bias.
In discussing the results, the investigators noted that both short- and long-term exposure to PM2.5, PM10, and NO2 were estimated to be significantly associated with higher risk of HF, whereas only short-term exposure to SO2 and CO had significant associations with HF. Neither short- nor long-term exposure to O3 was shown to be significantly associated with increased HF risk.
The researchers discussed strengths of their study, including assessing the relationship of long-term exposure to particulate and gaseous air pollutants with HF for the first time and incorporating studies conducted in different countries and regions to provide a more extensive evaluation of the impact on HF.
Limitations that the investigators discussed included significant heterogeneity across all pollutants in both short- and long-term exposures, the assessment of only each individual pollutant and not the combined effect, and limited information from LMICs about gaseous pollutants.
“Our results reinforce the impact of air pollution on cardiovascular health. Sustained public and environmental policies and actions aimed at controlling air pollution are needed to reduce the burden of HF,” the study authors concluded.
Jia Y, Lin Z, Li C, et al. Effect of air pollution on heart failure: systematic review and meta-analysis. Environ. Health Perspect. 2023; 131(7). doi:10.1289/EHP11506