The researchers carried out a total of 82 single runs covering the length of 176 km. These runs were repeated on a 2.1 km predefined route between the origin (University campus) and destination (a local school) to simulate morning drop-off (8-10 AM; local time) and afternoon pick-up (3-5 PM) times of school children.
Compared with cyclist height, the average bike-trailer concentration of coarse (fine) particles was higher by up to 14% and 18% during morning and afternoon runs, respectively. The lockdown restrictions when schools were closed led to a reduction in bike-trailer concentrations by up to 91% compared with eased lockdown period when schools re-opened in March 2021.
The researchers also tried trailer covers, which led up to a 50% reduction in fine particles during morning runs. However, that doesn’t change the outcome as the abstract of the research states:
“Young children carried in bike trailers are exposed to higher air pollution concentrations compared with the cyclist, particularly during peak morning periods at urban pollution hotspots such as traffic lights.”