Major study of 59 million Americans shows fine particles from air pollution increase heart disease risk

In a recent study published in BMJ, researchers assessed exposure-response relationships between chronic fine-sized particulate matter (PM2.5) exposure and the likelihood of first-time hospitalization for cardiovascular disease (CVD) subgroups.

Study: Exposure-response relationship between chronic exposure to fine particles and risk of hospitalization for major cardiovascular diseases: a population-based cohort study.  Image Credit: Kzenon/Shutterstock.comStudy: Exposure-response relationship between chronic exposure to fine particles and risk of hospitalization for major cardiovascular diseases: a population-based cohort study., Image Credit: Kzenon/


PM2.5, a minor component of air pollution, significantly contributes to CVD by inducing inflammation, vasoconstriction, cardiac electrical abnormalities, and blood clot formation.

Chronic exposure increases the risk of CVD-related hospitalization and death. Studies often focus on one or two CVD subtypes, neglecting to explore sensitive ones.

Comparing effect sizes across subtypes can help us understand the processes and recommend targeted strategies to reduce the impact of PM2.5.

about the study

In the current population-based cohort study, researchers evaluated exposure-response correlations between chronic PM2.5 Risk and probability of initial hospitalization for the seven main CVD subtypes and their combinations.

The study included Medicare beneficiaries aged 65 and older in the continental United States (US) from 2000 to 2016. The team added fine particulate matter estimates calibrated to each participant's residence postal code as a proxy for exposure assessment.

The primary outcome measures were initial hospitalization risk for cerebrovascular diseases, ischemic heart diseases, cardiomyopathy, heart failure, valvular heart diseases, abdominal and thoracic aortic aneurysms, arrhythmias, or a combination of these cardiovascular disease subtypes.

The researchers designed a causal-type framework that is resistant to confounding effects and biases caused by inaccuracies in exposure-response estimates.
The study included Medicare beneficiaries aged 65 and older living in the United States (US) and registered with the fee-for-service program from 2000 to 2016.

The researchers created a separate cohort for each CVD subtype by tracking each beneficiary annually until the initial hospitalization, death, or study termination, whichever came first.

They examined the risk of initial hospitalization for composite CVD outcomes by monitoring each beneficiary year until initial hospitalization for the investigated CVD, mortality, or study termination, whichever occurred first. Formed another study group.

The researchers used spatially weighted logistic regression to estimate daily ambient PM 2.5 values ​​on a 1.0 km2 grid across the United States from 2000 to 2016.

They blended predictions from machine-learning-based algorithms and incorporated information sources such as weather, satellite imagery, land use factors, monitoring information, and chemical model simulations.

They used regression calibration to improve grid-level particulate matter estimates and eliminate biases in health-impact estimates due to exposure errors.


The research included 59,761,494 individuals with 476,953,892 follow-up years; The majority were white (84%), with a higher proportion of female beneficiaries (55%). Most participants (75%) were between 65 and 74 years of age when the research began.

During the trial, 18% of participants enrolled with Medicaid. 22% required hospitalization due to a combination of cardiovascular disease. The most common CVD subtype was ischemic heart disease, which affected 8.8% of recipients.

Other common diseases were cerebrovascular disease (7.7%), heart failure (6.6%), and arrhythmias (6.5%). Three-year average exposure to PM2.5 was associated with an increased relative risk of early hospitalization for cerebrovascular diseases, ischemic heart diseases, cardiomyopathy, heart failure, abdominal and thoracic aortic aneurysms and arrhythmias.

Exposure-response curves for composite cardiovascular disease showed a monotonically increased risk related to exposure to fine particles.

Exposures greater than ≤5.0 µg m-3 [air quality standard issued by the World Health Organization]The relative risk at exposures ranging from 9.0 to 10 µg m-3 during the analysis, including the United States mean of 9.70 µg m-3, was 1.3.

The risk of composite CVD-related hospitalization increased from 2.6% with exposures less than or equal to 5.0 μg m-3 to 3.4% with exposures between 9.0 and 10 μg m-3.

Effects persisted for ≥3.0 years after exposure to PM2.5. Education, age, health care access, and neighborhood socioeconomic deprivation influenced PM2.5 sensitivity.

The highest risk for overall cardiovascular disease and the most common cardiovascular disease CVD subtypes (cerebrovascular disease, ischemic heart disease and heart failure) was related to immediate PM2.5 exposure at lag 0, and a significantly lower effect at lag 1.0 followed by a at lag 2.0. Shortage.

Female beneficiaries were more likely to develop overall cardiovascular disease, heart failure, and ischemic heart disease, although the risk of cardiomyopathy was lower.

Young beneficiaries and individuals aged 65 to 74 years are more likely to be hospitalized for CVD and subtypes. People living in areas with low high school graduation rates, high deprivation levels, or long hospital distances likely experienced the greatest consequences.


The study findings showed that long-term exposure to fine-sized particles increases the risk of cerebrovascular diseases, ischemic heart disease, cardiomyopathy, heart failure, arrhythmias, and abdominal and thoracic aortic aneurysms.

Exposure-response curves shifted for several CVD subtypes, indicating the lack of a safe range for cardiovascular health.

Adhering to WHO's air quality standards of ≤5 µg/m3 can provide significant benefits. Susceptibility varies depending on participants' age, health care access, educational attainment, and neighborhood deprivation.

Cardiac arrhythmias and heart failure are among the most vulnerable CVD subtypes in patients exposed to PM2.5.

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