Characterisation of particulates and carcinogenic polycyclic aromatic hydrocarbons in wintertime wood-fired heating in residential areas

Wood as a renewable and worldwide available fuel is used for residential heating in small-scale firings during winter. This wood combustion can cause very high emissions of inhalable particles resulting in short and long-term health effects. The target of this study was to characterise particulate matter, emissions of polycyclic aromatic hydrocarbons (PAHs) and their size distribution and to show that those emissions can be found in the ambient air of residential areas with wood-fired heating. Emission samples were collected from pellet stove and log wood boiler under different combustion conditions. Ambient PM10 sampling was performed during two winter seasons at two rural residential areas near Stuttgart in Germany. Samples were extracted using toluene with ultrasonic bath and analysed by gas chromatography mass spectrometry (GC–MS). Twenty-one PAH compounds including nine carcinogenic ones were detected and quantified. It was found that emission concentrations of carcinogenic PAHs were higher during incomplete combustion compared to complete combustion. Significant amounts of ambient PAHs were found in the residential villages, where the contribution of carcinogenic PAHs was 44% of total PAHs in the ambient air during winter 2009. The morphology and elemental analysis of ambient particles were also investigated. The findings indicate a rising concern to reduce emissions from wood-fired heating during winter in residential areas and underline the importance of using good wood combustion technologies to improve the air quality.