Indoor moss biomonitoring proving construction-related pollution load from outdoors

Indoor pollution load in an office environment was investigated during ongoing construction works in the vicinity using the wet moss biomonitoring technique. Monitoring boxes were placed inside eight offices with mechanical ventilation located on three floors and with four different orientations to outdoor construction works for 8 weeks. Samples were collected every two weeks for two months, and the concentrations of selected elements: Al, As, Ca, Cd, Cr, Cu, Fe, Mg, Mn, Pb, Si and Zn were determined. Total deposition (composition, number and size of particles) was determined in the samples too. Correlation analysis complemented by Principle Component Analysis (PCA) was performed using a compositional approach. Concentrations correlated significantly among crustal elements and among road dust elements. PCA identified three groups of elements – representing construction dust, traffic origin and indoor origin, while those associated with construction dust had the highest contribution. The elevation (floor) affected the composition of the samples the most, the orientation to the pollution sources was secondary. Construction dust was most dominant on the 1st floor; samples from the sheltered sites were negatively associated with construction dust elements; here, the finest particles were also observed. Starting at 6 weeks of exposure, construction dust elements started to dominate in samples. Construction dust is a serious pollution problem, and its infiltration from the outdoors is apparent even in mechanical-ventilated indoor environments. Moss indoor monitoring technique was proven to be a suitable cost-effective alternative to automatic air samplers in determining the outdoor-originating pollution loads indoors.