Decadal Shifts in PAH Sources and Health Risks in China under Clean Air Actions.

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Public Health

Background:

• Long-term monitoring of atmospheric polycyclic aromatic hydrocarbons (PAHs) is crucial for assessing pollution and health risks.
• Accurate source attribution of PAHs, particularly distinguishing biomass burning from fossil fuel combustion, remains a challenge.

Purpose of the Study:

• To precisely quantify sources of atmospheric PAHs in China across multiple years (2008, 2013, 2017, 2020).
• To evaluate the effectiveness of air quality policies on PAH emission trends and associated health risks.

Main Methods:

• Integration of radiocarbon (¹⁴C) analysis of black carbon with positive matrix factorization (PMF) for source apportionment.
• Analysis of PAH source contributions and toxicity (BaP_eq) trends over time.

Main Results:

• Air quality actions in Phase I (2013-2017) significantly reduced PAHs (-49.4%), mainly from reduced coal combustion.
• Phase II (2018-2020) showed stable biomass burning emissions, but rising transportation emissions became a major contributor.
• A concurrent increase in PAH toxicity and health risks was observed during Phase II, linked to traffic exhaust.

Conclusions:

• China's air quality policies have had differential impacts on PAH sources, with initial success in reducing coal-related emissions.
• The growing contribution of traffic emissions poses a significant challenge, increasing overall PAH toxicity and health risks.
• Urgent energy transformation and vehicle electrification are necessary to mitigate future PAH burdens and protect public health.