Campfire Smoke as a Source of PAH and BTEX Inhalation Exposure: Implications for Cancer Risk

Introduction
Campfires are a popular outdoor recreational activity that promotes social interaction and leisure. However, wood combustion generates particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs), volatile organic compounds (VOCs), and BTEX compounds, which may adversely affect human health. While exposure to these pollutants has been extensively studied in occupational settings, data regarding inhalation exposure during recreational campfire activities remain limited. This pilot study aimed to assess air pollution levels and estimate the associated cancer risk for campfire participants.

Materials and Methods
Measurements were conducted during a single campfire event involving sausage roasting over a wood fire. Air samples were collected at a distance of 1 m from the fire and at a background site located 100 m away. VOCs and BTEX compounds were sampled using charcoal CSC tubes, while gaseous and particle-bound PAHs were collected on XAD-2 resin tubes. PM2.5 concentrations were monitored continuously using a PALAS AQ Guard optical aerosol spectrometer. Incremental lifetime cancer risk (ILCR) was estimated according to US EPA methodology. Simultaneous background measurements enabled the determination of the campfire's contribution to pollutant concentrations.

Results
Pollutant concentrations measured near the campfire were substantially higher than background levels. The average PM2.5 concentration during the 2.5-hour event reached 350µg/m³. When expressed as a 24-hour average, this corresponds to approximately 42µg/m³, exceeding the World Health Organization daily guideline. Total airborne PAH concentration reached 29.85µg/m³, compared with less than 0.5µg/m³ at the background site. The gas phase dominated PAH concentrations, with naphthalene and phenanthrene as the main contributors. Benzene concentration near the fire reached 153µg/m³.

Conclusions
Occasional participation in campfires is unlikely to pose a significant health risk. However, individuals spending prolonged periods near fires may experience elevated cancer risk. Risk estimates indicate that adults not consuming campfire-cooked food may attend up to 31 campfire events annually while remaining below the acceptable risk threshold (ILCR < 10⁻⁵).