A recognized problem is the emission of fine particulate matter to the air, especially in urban areas that have a high concentration of pellet heating systems or coal or oil heating systems in close proximity.
一个公认的问题是，细微颗粒物在空气中的排放，特别是在靠近具有高的浓度颗粒加热系统或煤或油加热系统的城市地区。