The enhancement of PM2.5 mass and water-soluble ions of biosmoke transported from Southeast Asia over the Mountain Lulin site in Taiwan

► This paper reports six years' aerosol data collected at Mt. Lulin (2862 m a.s.l.). ► It is the only site that receives aerosol from Southeast Asia in the West Pacific. ► The PM2.5 at around 4 μg m−3 can represent global background 3 km above ground. ► The observation found the most active biomass burning was in 2004. ► Great enhancement of PM2.5 and water-soluble ions observed for the transported biosmoke.