Cities in southern Chile are facing high levels of PM_2.5 because of wood burning pollution. We quantify the contribution of wood smoke to fine particles in two mid-size cities: Molina and Valdivia, located in different climate zones. The sampling campaigns were carried out during austral winter (July to September) in 2018 (Molina) and 2019 (Valdivia). 24-h filter samples were analyzed for carbonaceous compounds, secondary ions, metals, and particle-phase organic molecular markers. Average winter concentrations of PM_2.5 were 53 ± 32 μg/m³ (average ± standard deviation) in Molina and 89 ± 55 μg/m³ in Valdivia. The major component of fine particles was organic matter, representing more than 70% of PM_2.5. Concentrations of organic molecular markers were used in a receptor model (US EPA CMB8.2) to identify and quantify primary sources of PM_2.5. The major source of PM_2.5 was wood smoke, which accounted for 41.55 ± 9.77 μg/m³ (62.9 ± 15.3%) in Molina and 43.65 ± 24.06 μg/m³ (51.7 ± 21.1%) in Valdivia. Secondary organic aerosols (SOA) generated from inefficient wood burning, contributed 20.4 ± 17.7% in Molina and 28.9 ± 27.6% in Valdivia. Secondary inorganic ions and dust are minor sources of PM_2.5. The total contribution of wood smoke (adding primary wood smoke and SOA) could be as much as 83% in Molina and 81% in Valdivia, during the winter season.

智利南部的城市由于燃木污染而面临PM _2.5的高水平。我们对位于不同气候区的两个中型城市：莫利纳和瓦尔迪维亚的木质烟雾对细颗粒的贡献进行了量化。采样活动是在2018年（莫利纳州）和2019年（瓦尔迪维亚）的南方冬季（7月至9月）进行的。分析了24小时过滤器样品中的碳质化合物，次级离子，金属和颗粒相有机分子标记。冬季的PM _2.5的平均浓度在莫利纳（Molina）为53±32μg/ m ³（平均值±标准偏差），在瓦尔迪维亚（Valdivia ）为89±55μg/ m ³。细颗粒的主要成分是有机物，占PM _2.5的70％以上。在受体模型（US EPA CMB8.2）中使用了有机分子标记物的浓度，以鉴定和量化PM _2.5的主要来源。PM _2.5的主要来源是木烟，其在莫利纳（Molina）占41.55±9.77μg/ m ³（62.9±15.3％），在瓦尔迪维亚占43.65±24.06μg/ m ³（51.7±21.1％）。木材燃烧效率低下产生的次级有机气溶胶（SOA）在莫利纳（Molina）和瓦尔迪维亚（Valdivia）占20.4±17.7％。二次无机离子和粉尘是PM _2.5的次要来源。在冬季，莫利纳和瓦尔迪维亚的木烟总贡献（加上原始木烟和SOA）可能高达83％，而在瓦尔迪维亚则高达81％。