Quantifying the wildfire contribution to PAH concentrations and health effects

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Public Health

Background:

• Wildfires are a growing source of toxic air pollutants, including carcinogenic polycyclic aromatic hydrocarbons (PAHs).
• Climate change is projected to increase wildfire frequency and intensity, exacerbating air quality concerns.

Purpose of the Study:

• To quantify the influence of wildfire events on PAH concentrations, chemistry, and associated cancer risk.
• To assess the impact of fire-derived PAHs on human health risks globally.

Main Methods:

• Utilized a global three-dimensional chemical transport model to simulate fire events and PAH behavior.
• Analyzed PAH concentrations, chemical transformations, and partitioning into fine particulate matter (PM2.5).

Main Results:

• Wildfires contribute significantly to local PAH concentrations (up to 42%) and globally (approx. 4.6%).
• Fire emissions increase PM2.5, alter atmospheric oxidants, and form more toxic PAH degradation products (up to 55% of fire-sourced risk).
• Fire-derived PAHs are 51% more carcinogenic per mass than non-fire PAHs, with some regions exceeding health risk thresholds due to fire pollution.

Conclusions:

• Wildfires elevate PAH levels and increase their toxicity through chemical transformations.
• Increasing wildfire activity necessitates enhanced monitoring and mitigation strategies for public health protection.
• Addressing fire-related air pollution is crucial for managing cancer risks, particularly in fire-prone regions.