Air pollution, both indoor and outdoor raises death risk: SPACE study
Iran: Air pollution, whether indoors (fuel use in poorly ventilated homes) or outdoors increases the risk of all-cause and cardiovascular death over a period of 10 years, reveals a study of more than 50,000 adults living in Iran. The findings from the Spatial Assessment of Cardiovascular Events (SPACE) study was published in the journal PLOS One on June 24, 2022.
"Our findings show that the disease burden attributable to the environment may be as large as traditional cardiovascular risk factors," Michael B. Hadley, Icahn School of Medicine at Mount Sinai, New York, New York, USA, and colleagues wrote in their study. "This represents a critical opportunity for targeted policies and programs. Additionally, these findings demonstrate the feasibility and utility of environmental data incorporation in survival models, even in low-income settings.
Environmental exposures contribute to a growing proportion of global mortality. Considering this, there is a need for large cohort studies to characterize the independent impact of environmental exposures on mortality in low-income settings. Dr. Hadley and the team, therefore, developed a spatial environmental model to estimate the independent associations between these environmental exposures and all-cause and cardiovascular mortality.
The researchers collected data on individual and environmental risk factors for a multiethnic cohort of 50,045 individuals in a low-income region in Iran. Environmental risk factors included: household fuel use and ventilation; ambient fine particular matter air pollution; distance to percutaneous coronary intervention (PCI) center; proximity to traffic; population density; socioeconomic environment; local land use; and nighttime light exposure.
The key findings of the study were as follows:
- Several environmental factors demonstrated associations with mortality after adjusting for individual risk factors. Ambient fine particulate matter air pollution predicted all-cause mortality (per μg/m3, HR 1.20) and cardiovascular mortality (HR 1.17, 95% CI 0.98, 1.39).
- · Biomass fuel use without chimney predicted all-cause mortality (reference = gas, HR 1.23) and cardiovascular mortality (HR 1.36).
- · Kerosene fuel use without chimney predicted all-cause mortality (reference = gas, HR 1.09) and cardiovascular mortality (HR 1.19).
- · Distance to PCI center predicted all-cause mortality (per 10km, HR 1.01) and cardiovascular mortality (HR 1.02).
- · Proximity to traffic predicted all-cause mortality (HR 1.13).
- · In a separate validation cohort, the multivariable model effectively predicted both all-cause mortality (AUC 0.76) and cardiovascular mortality (AUC 0.81).
- · Population attributable fractions demonstrated a high mortality burden attributable to environmental exposures.
The authors wrote in their conclusion, "independent of each other and of individual risk factors, several environmental factors predicted cardiovascular and all-cause mortality. Mortality attributable to environmental factors represents a critical opportunity for targeted policies and programs."
Citation: Hadley MB, Nalini M, Adhikari S, Szymonifka J, Etemadi A, Kamangar F, et al. (2022) Spatial environmental factors predict cardiovascular and all-cause mortality: Results of the SPACE study. PLoS ONE 17(6): e0269650. https://doi.org/10.1371/journal.pone.0269650
