Concentrations, Source Identification, and Lung Cancer Risk Associated with Springtime PM_2.5-Bound Polycyclic...

Area of Science:

• Environmental Science
• Public Health
• Chemical Analysis

Background:

• Particulate matter (PM2.5) is a major air pollutant linked to adverse health effects.
• Polycyclic Aromatic Hydrocarbons (PAHs) are carcinogenic compounds often adsorbed onto PM2.5.
• Understanding PAH sources and associated health risks is crucial for urban air quality management.

Purpose of the Study:

• To investigate the pollution levels, identify sources, and assess the lung cancer risk of PM2.5-bound PAHs in Nanjing during spring.
• To analyze the diurnal variations of PAHs and their carcinogenic potential.
• To evaluate the inhalation exposure and incremental lung cancer risk across different demographic groups.

Main Methods:

• PM2.5 samples were collected in Nanjing in spring 2016.
• Sixteen priority PAHs were extracted and analyzed using established methods.
• Diagnostic ratios were employed to identify PAH emission sources.
• Inhalation exposure and incremental lung cancer risk were calculated based on measured concentrations.

Main Results:

• Mean concentrations of PAHs and BaP equivalent (BaPeq) were 3.98 ± 1.01 ng/m³ and 0.29 ± 0.08 ng/m³, respectively, considered low globally.
• PAH levels peaked during morning and evening traffic rush hours.
• Diagnostic ratios indicated traffic exhaust, particularly from diesel vehicles, as the primary PAH source.
• Estimated median incremental lung cancer risks were below 10⁻⁸ for all demographic groups, indicating low risk.

Conclusions:

• PM2.5-bound PAHs in Nanjing during spring are at low levels, with traffic exhaust being the main contributor.
• Diurnal patterns of PAH concentrations correlate with traffic activity.
• The assessed lung cancer risk associated with PM2.5-bound PAHs is low for the population in Nanjing.