Inhalable particles include all particulate matter with a diameter smaller than 10 micrometers (PM10), which is broken down into finer particles smaller than 2.5 micrometers (PM2.5), which can enter the lung, and ultrafine particles with diameters less than 0.1 micrometers (100 nanometers), which can enter the blood stream.

A Helmholtz Zentrum München research team led by Prof. Dr. Annette Peters, head of the research program Epidemiology at the German Center for Diabetes Research (DZD), and Dr. Alexandra Schneider studied how ultrafine particles specifically affect the heart. They provided 64 study participants with measuring devices which recorded particle number concentrations as well as the heart activity (ECG, electrocardiogram) during daily activities. Data from an urban background station for particulate matter were considered. The recruited participants had a confirmed diagnosis of impaired glucose tolerance (IGT) or type 2 diabetes.

Change in heart rate variability after only short-term exposure

"Elevated concentrations of ultrafine particles, e.g. in dense road traffic, led to a change in heart rate variability* of the participants after only five minutes," said Peters. "Moreover, we were able to confirm effects that are already known, for example that fine particles over the course of an hour and noise are associated with impaired cardiac function."

The adverse health effects of inhalable and/or fine particles have already been established in other studies. In the present study they occur below the EU threshold limit value, which has existed for the last ten years. The role of ultrafine particles, however, is unclear: Scientists expect additional adverse health effects - but to date no threshold limit values have been established.

Health risks?

"The results are alarming because ultrafine particles occur generally in the environment and pose health risks for all of us - but especially for people who already have an elevated risk for cardiovascular disease, such as the individuals with diabetes in this study," said Peters. "We hope that with our data, we can substantiate the demands for threshold limit values and environmental standards in the future."

Citation: Peters, A. et al. (2015), Elevated particle number concentrations induce immediate changes in heart rate variability: a panel study in individuals with impaired glucose metabolism or diabetes, Particle&Fibre Toxicology, doi: 10.1186/s12989-015-0083-7