Road traffic pollutions may trigger asthma symptoms and exacerbations, and this is mainly attributed to polycyclic aromatic hydrocarbon core diesel exhaust particles (DEP).

The authors carried out a randomised crossover study enrolling 60 non-smoking adults with stable mild and moderate asthma. Each participant was required to walk for 2 hours (10.30– 12.30 hours) along Oxford Street, London (used by …