Effects of the exposure to ultrafine particles on heart rate in a healthy population

The correlation amongst exposure to ultrafine particle concentrations and heart rate in a large healthy population was investigated. The study was conducted by continuously monitoring for seven days fifty volunteers in terms of exposure to particle concentrations, heart rate and physical activity performed through portable monitors. Data were analyzed adopting a linear mixed model able to manage the obtained repeated measures and to recognize a general trend resulting from the subject-specific patterns. Results show that the short-term exposure to ultrafine particle concentrations is positively associated with the heart rate for the different physical activities of the subject investigated (laying down, sitting, standing positions). In particular, a logarithmic correlation was recognized with a sharper increase of about 4–6 bpm for a variation of the particle number concentration of 2 × 104 part/cm3 and a slighter effect for further increases of about 0.1–0.2 × 10−4 bpm/(part/cm). Capsule A positive correlation can be associated between the exposure to ultrafine particles and the heart rate.