Recent studies have shown that indoor environment inmuseums can pose a risk to cultural heritage objectsdue to adverse effects. Cur rent practice is movingtowards protection of artwor ks such as paintings byplacing them into microclimate fr ames (mc-frames).However, little is known about the effects of enclosingpaintings in such a way. Pollutants can enter mc-framesfrom outside the frame (e.g. NOx) or they can be originatedfrom materials within the frame (e.g. volatileorganic compounds). In this study, pollutant concentrationsof organic (VOCs, acetic and for mic acid,formaldehyde) and inor ganic compounds (NO2, SO2 andO3) were measured for the fir st time both inside and outside15 mc-frames. The results showed that the concentrationof inorganic gases is lower inside the mc-framesthan outside. In contrast, higher concentrations ofpotentially aggressive or ganic compounds, such asacetic and formic acid, toluene, α-pinene, p- and mxylenes,limonene and 3-carene, were measured insidethan outside the frames.