Using native epiphytic ferns to estimate the atmospheric mercury levels in a small-scale gold mining area of West Java, Indonesia

► Hg concentration in native epiphytic fern (Asplenium nidus) is corresponded with Hg in ambient air around ASGM in Indonesia. ► Hg level in air can be estimated from the Hg in A. nidus using a regression equation. ► Biomonitoring with A. nidus is a suitable means for estimating atmospheric Hg levels in tropical Asia.