Houston Methodist Researcher Exposes Link Between Air Pollution, Cardiometabolic Disease and Cancer

Individuals' exposure to environmental pollution is an overlooked and underappreciated risk factor for heart disease and cancer, according to two recent review articles co-authored by a researcher at the Houston Methodist DeBakey Heart and Vascular Center.

In the publications, Dr. Sadeer Al-Kindi, associate director of Cardiovascular Prevention & Wellness and medical director of The Center for Health & Nature at Houston Methodist, examines how pollutants in the air not only exacerbate cardiometabolic diseases such as diabetes but also compound health risks in cancer patients.

"Genetically humans are 99% similar, and the 1% genetic difference does not account for the full variety of conditions and diseases we see," Dr. Al-Kindi said. "In reality, where you live and what you're exposed to often matters more than your genetics with respect to disease, and yet our current understanding of how these factors affect our health is insufficient."

The papers — one published in The Lancet Diabetes & Endocrinology, the other in JACC: CardioOncology — address this information gap by providing a summary of the epidemiological evidence and mechanistic underpinnings linking air pollution with cardiovascular disease.

The research also outlines approaches to improve awareness and recommends personal-level, community, governmental and policy interventions to help mitigate the growing global public health risk of air pollution exposure.

The link between air pollution and cardiometabolic disease

The Lancet paper highlights how long-term exposure to fine particulate matter is responsible for an estimated 20% of global type 2 diabetes cases.

Known as PM2.5, airborne particles with a diameter of 2.5 micrometers or smaller are primarily emitted from vehicles, industrial activities and wildfires.

The authors call attention to an alarming statistic — that nearly 99% of the global population lives in areas where air pollution levels exceed World Health Organization air quality guidelines (<5 μg/m³ annually). Instead, the mean global annual population-weighted PM2.5 concentration is estimated at 32.8 μg/m³.

According to Dr. Al-Kindi, the primary investigator of the Lancet article, air pollution's impact on heart health extends far beyond traditional risk factors.

"For years, cardiologists have focused on internal contributors such as cholesterol, obesity and blood pressure," he noted. "But our research is increasingly showing that high exposure to air pollution can raise your risk of type 2 diabetes by up to 25%, making it one of the largest independent risk factors."

The article outlines the mechanisms through which air pollution contributes to cardiometabolic risk, including systemic inflammation, oxidative stress, hypothalamic-pituitary-adrenal axis activation, central nervous system activation and disruptions in glucose metabolism.

Research from Dr. Al-Kindi and others has shown that prolonged exposure to pollutants can increase insulin resistance, elevate blood pressure and heart rate, and accelerate the development of atherosclerosis and other forms of heart disease, the leading cause of death globally.

In addition to advocating for cleaner energy policies, governing bodies and health organizations can impact this public health crisis through education and targeted interventions.

Portable air cleaners, for instance, are practical and inexpensive in-home strategies that can help acutely reduce PM2.5 exposures by as much as 60%, the paper suggests.

A 'double whammy' for cancer patients

In the JACC: CardioOncology paper, Dr. Al-Kindi and colleagues reviewed multiple large-scale studies examining how air pollution compounds risk for patients who already face a heightened vulnerability — they're battling cancer.

The researchers found that cancer patients exposed to high levels of PM2.5 were significantly more likely to develop cardiovascular disease, a leading cause of non-cancer-related deaths among survivors of cancer.

"Patients with cancer are already dealing with aggressive treatments that strain the heart," Dr. Al-Kindi explained. "When you add the chronic stress of air pollution exposure, it creates a perfect storm for cardiovascular complications."

A 2021 study examining the medical records of more than 5.5 million cancer patients and survivors found that a 10 μg/m³ increase in PM2.5 was associated with 24% increase in cardiopulmonary mortality and 31% increase in cardiovascular disease mortality.

Not surprisingly, lung cancer patients exposed to higher levels of air pollution showed the strongest and most consistent association with cardiovascular disease. But the connection was also pronounced in breast, prostate, kidney and bladder cancer patients as well.

The article also explored health disparities in air pollution exposure, showing that lower-income and minority populations often face the highest environmental burdens.

"There is an environmental justice component to this issue," Dr. Al-Kindi noted. "Communities with the least resources often experience the worst air quality, putting their residents at increased risk for both heart disease and cancer."

Moving toward solutions

While the findings highlight a serious public health challenge, Dr. Al-Kindi believes they also present an opportunity for meaningful intervention.

The studies should help regulators and public health officials advocate for policies that improve air quality, such as stricter emissions regulations. They also call for individual-level actions like wearing masks in high-pollution areas and using air filtration systems in susceptible individuals' homes.

"There is no single solution to air pollution's impact on heart disease, but awareness is the first step," Dr. Al-Kindi said. "Our goal is to integrate environmental health into mainstream cardiology and oncology discussions. The more we understand these links, the better we can protect at-risk populations."

With Houston Methodist's continued research leadership in cardiovascular prevention and environmental health, Dr. Al-Kindi and colleagues hope to pave the way for a heightened awareness that considers not just genetics and lifestyle in risk prediction models, but the air we breathe and the environment in which we live.