A technique for continuous monitoring of atmospheric corrosivity was developed. An electronic unit measures and records changes in the electrical resistance of a thin metal track applied on an insulating substrate. If the metal corrodes, the effective cross-sectional area of the track decreases and the electrical resistance increases. Sensors made of silver, copper, iron / steel, zinc, lead, tin, bronze and brass at thicknesses from 50 nm to 250 Êm were tailored for environments with different corrosivity. The developed technology proved to provide subAngstrom (<10-10 m) sensitivity allowing for real-time corrosion monitoring even in low-corrosive indoor cultural heritage facilities. Laboratory tests showed good reproducibility of the technique with standard deviation of parallel measurements up to ±20% for metals corroding in a given environment mostly uniformly. Since the technique measures the maximal depth of corrosion attack, the response is somewhat higher compared to methods measuring the average corrosion depth. Several examples from a wide testing programme in partner museums, archives, libraries and other institutions were selected to show successful applications of the technique for qualifi cation and comparison of air quality control in indoor premises, assessment of new buildings and storage facilities, air quality control during transport and temporary exhibitions and fundamental studies of optimal conservation and storage procedures. A fi rst outline of a classifi cation system for lead, which is particularly sensitive to presence of carboxylic acids, is given. The technique has a large potential as an independent method of air quality monitoring in facilities.