The European heritage of the organ is preser ved innumerous historical instruments. A major threat to thisheritage are har mful indoor environments. Organicacids, also in combination with condensation phenomena,create pipe cor rosion causing serious damage to thepipes. Harmful humidity conditions can create cracks inthe wooden par ts of the organ, making the instrumentunplayable.The EC funded SENSORGAN project (contract 022695)objectives were to make available new instrumentationfor monitoring and detection of harmful environmentsfor or gans through development of sensors for real timemeasurement. The system contains three different sensorsto detect: (i) levels of organic acids harmful toorgan pipes, (ii) envir onments damaging to woodenparts of organs, (iii) possible dew for mation insideorgan pipes.The sensors were designed in order to be placed in theorgan without disturbing playing or affecting the sound.The sensors were applied in the historical organ in theMinor Basilica of St. Andrew the Apostle, Olkusz, Poland.Data collected from the sensors was analysed and conclusionswere drawn for publications and mitigation strategies.