Spatial distribution of the size-fractional PNC and Pedestrian exposure to PM at an urban signalized intersection

To evaluate the respiratory health risk of pedestrians at signalized intersections, it is crucial to accurately investigate their spatial distribution of particulate matter (PM) in the air and the respiratory exposure dose to the public. The particle number concentrations (PNCs) of different sizes (10-2500 nm) along the horizontal and vertical vibrations of the intersection were measured in Xi'an, China, and the respiratory deposition dose (RDD) rate of pedestrians was calculated to estimate the pedestrian exposure level. The mean PNC at the intersection's entrance (1.59 x 10(4) # cm(-3)) was larger than at its exit (1.34 x 10(4) # cm(-3)) irrespective of the particle mode. At the exit, moreover, the PNC values decreased exponentially with increasing distance from the parking baseline of the intersection, while no such damping characterized the entrance to it. Concerning the vertical vibration of the intersection, both nucleation and Aitken modes of PNC peaked at a 0.4-m height and the maximum PNC in the accumulation mode and coarse mode appeared at a height of 3.4-4.5 m. Average RDD rate at the signalized intersection's entrance and exit was respectively 8.103 mu g h(-1) and 7.523 mu g h(-1). For this same intersection, the highest PM exposure dose was 8.444 mu g h(-1) for the elderly, followed by 8.061 mu g h(-1) for adults, and 3.221 mu g h(-1) for children.

Automated summary

The study investigates the respiratory health risk of pedestrians at a signalized intersection in Xi'an, China, by analyzing the spatial distribution of particulate matter (PM) and the respiratory exposure dose. Results show that the particle number concentrations (PNCs) were higher at the entrance compared to the exit, and peaked at different heights for different particle modes in the vertical vibration of the intersection. The study also calculated the respiratory deposition dose (RDD) rate for pedestrians at the intersection, showing varying exposure levels for different age groups.