Efficiency of log wood combustion affects the toxicological and chemical properties of emission particles

Abstract

Context: Particulate matter (PM) has been identified as a major environmental pollutant causing severe health problems. Large amounts of the harmful particulate matter (PM) are emitted from residential wood combustion, but the toxicological properties of wood combustion particles are poorly known.

Objective: To investigate chemical and consequent toxicological characteristics of PM₁ emitted from different phases of batch combustion in four heating appliances.

Materials and methods: Mouse RAW264.7 macrophages and human BEAS-2B bronchial epithelial cells were exposed for 24 h to different doses (15–300 µg/mL) of wood combustion particles. After the exposure, cytotoxicity, genotoxicity, production of the inflammatory mediators (TNF-α and MIP-2) and effects on the cell cycle were assessed. Furthermore, the detected toxicological responses were compared with the chemical composition of PM₁ samples including PAHs, metals and ions.

Results: All the wood combustion samples exerted high cytotoxicity, but only moderate inflammatory activity. The particles emitted from the inefficient phase of batch combustion in the sauna stove (SS) induced the most extensive cytotoxic and genotoxic responses in mammalian cells. Polycyclic aromatic hydrocarbons (PAHs) and other organic compounds in PM₁ samples might have contributed to these effects. Instead, water-soluble metals seemed to participate in the cytotoxic responses triggered by the particles from more efficient batch combustion in the masonry heaters. Overall, the toxicological responses were decreased when the combustion phase was more efficient.

Conclusion: Efficiency of batch combustion plays a significant role in the harmfulness of PM even under incomplete wood combustion processes.

Keywords::

• Wood combustion
• particulate matter
• cytotoxicity
• genotoxicity
• inflammation
• chemical composition

Acknowledgments

This project belongs to the KANTIVA Bioenergy Research Centre and spearhead project called Sustainable Bioenergy, Climate Change and Health in the University of Eastern Finland. The authors wish to thank Ms. Arja Rönkkö, Ms. Heli Martikainen, Ms. Miia Koistinen and Ms. Arja Kinnunen for their excellent technical assistance in toxicological studies. Dr. Ewen MacDonald is acknowledged for revising the language of the manuscript.

Declaration of interest

This study was funded by the Finnish Funding Agency of Technology and Innovation (Tekes).