Sanjeev Bista, PhD laureate, under the supervision of Basile Chaix, DR INSERM

Using portable sensors, we measured personal concentrations of black carbon (BC), nitrogen dioxide (NO₂), nitrogen monoxide (NO), carbon monoxide (CO), ozone (O₃), and particles with aerodynamic diameters below 2.5 µm (PM_2.5). We collected participants’ ambulatory BP measurements (30-minute intervals) over two follow-up days. Inhaled doses of air pollutants were calculated from the ventilation rates estimated from body acceleration. Our study was conducted in Grand Paris, France.

We found that public transport, private motorized vehicles, and biking trip stages exposed participants to high BC concentration. In contrast, biking trip stages had higher inhaled doses of BC than all other modes due to the increased ventilation rate. The effect of BC exposure on BP decreased with the increase in exposure period, with prior 5-minute BC exposure increasing the systolic BP by 0.57 and diastolic BP by 0.36 mmHg per 1-μg/m³. Likewise, per quartile increase in air pollutants concentration (BC, NO₂, NO, CO and O₃) mixture in the previous 5-minute to 1-hour exposure windows were associated with systolic BP elevations decreasing from 2.13 mmHg to 1.40 mmHg, and similar results were observed for inhalation mixtures. 

Our finding implies that the existing bike lanes and newly proposed ones should be shifted further away than they are from motorized traffic. Reducing dependency on cars and promoting cycling for daily trips is one of the suggested pathways to reducing ambient pollution and improving cardiovascular health.