How do ultrafine particles in urban air affect ambulatory blood pressure

INTRODUCTION: Air in urban areas is usually contaminated with particle matter. High concentrations lead to a rise in the risk of cardiovascular and respiratory diseases. Some studies have reported that ultrafine particles (UFP) play a greater role in cardiovascular diseases than other particle matter, particularly regarding hypertensive crises and DBP, although in the latter such effects were described concerning clinical blood pressure (BP). In this study, we evaluate the relationship between 24-h ambulatory BP monitoring (ABPM) and atmospheric UFP concentrations in Barcelona. METHODS: An observational study of individual patients' temporal and geographical characteristics attended in Primary Care Centres and Hypertensive Units during 2009-2014 was performed. RESULTS: The participants were 521 hypertensive patients, mean age 56.8 years (SD 14.5), 52.4% were women. Mean BMI was 28.0 kg/m and the most prominent cardiovascular risk factors were diabetes (N = 66, 12.7%) and smoking (N = 79, 15.2%). We describe UFP effects at short-term and up to 1 week (from lag 0 to 7). For every 10 000 particle/cm UFP increase measured at an urban background site, a corresponding statistically significant increase of 2.7 mmHg [95% confidence interval = (0.5-4.8)] in 24-h DBP with ABPM for the following day was observed (lag 1). CONCLUSION: We have observed that a rise in UFP concentrations during the day prior to ABPM is significantly associated with an increase in 24 h and diurnal DBP. It has been increasingly demonstrated that UFP play a key role in cardiovascular risk factors and, as we have demonstrated, in good BP control.