Palma, April 29, 2026.– A new study published in the journal Diabetes Care reveals that long-term exposure to air pollution may contribute to an increase in total body fat as well as a reduction in lean mass (or fat-free mass) in older adults with overweight or obesity and metabolic syndrome.

The research, led by investigators from the Balearic Islands Health Research Institute (IdISBa) and the CIBER area of Obesity and Nutrition Physiopathology (CIBEROBN), in collaboration with researchers from the CIBER areas of Diabetes and Associated Metabolic Diseases (CIBERDEM) and Epidemiology and Public Health (CIBERESP), as well as other national and international centers, analyzed data from 1,454 participants in the PREDIMED-Plus trial. This multicenter study is a pioneering cardiovascular prevention trial in Spain, funded with more than €15 million through different competitive calls, with major contributions from the Carlos III Health Institute (ISCIII) and the CIBER Consortium.

The research team assessed residential exposure to air pollutants such as black carbon, fine particulate matter (PM2.5), and nitrogen dioxide (NO₂), and examined their association with detailed measurements of body composition obtained by bone densitometry, also known as DEXA or DXA (dual-energy X-ray absorptiometry). Participants were mainly from five Spanish cities (Pamplona, León, Palma, Reus, and Barcelona), with Barcelona showing the highest concentrations of the three air pollutants.

The results show that higher levels of air pollution are associated with a greater increase in total fat mass, as well as with greater losses of lean mass both after one year and after three years of follow-up. According to the authors, these changes in body composition are especially relevant because fat accumulation and lean mass loss are closely linked to an increased cardiometabolic risk, particularly in individuals with excess body weight.

Dr. Ariadna Curto, first author of the study, notes: “Black carbon, a clear marker of urban traffic, was the pollutant with the greatest impact. Living in areas with higher levels was associated with a loss of almost one kilogram of lean mass over three years, highlighting the importance of considering air pollution as an environmental factor that can influence metabolic health.”

Dr. Dora Romaguera, senior author of the study, adds: “Our study is also one of the first to analyze this association in relation to visceral fat, which accumulates in the abdominal cavity. The effect was only evident in participants under 65 years of age, suggesting that pollutants may favor greater visceral fat accumulation in younger adults, whose adipose tissue still has the capacity to expand.”

The authors call for future longitudinal studies to more precisely assess the role of visceral fat accumulation and lean mass loss in metabolically vulnerable populations such as the one studied. The study also reinforces the need for public policies aimed at reducing exposure to air pollutants and promoting healthier environments, especially in urban areas where pollution levels tend to be higher.

The CIBER (Biomedical Research Networking Center) is a cooperative research consortium that brings together basic and clinical research groups from across the country to work in a networked manner and transfer scientific results to clinical practice, industry, and society. It operates under the Carlos III Health Institute (ISCIII), which is the main funding and supervisory body.V