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This paper presents the preparation and characterisation studies of UV sensing films with a simple mathematical model for quantifying the lower UV irradiation duration/doses. To observe any appreciable changes in any properties of Poly-vinyl alcohol (PVA) films with UV irradiation, it has to be treated for few hours/days together. However, the technique presented here is an ultrasensitive method in which, the quantum dots (QDs) reinforced PVA film has become sensitive to UV radiations even for few seconds of exposure. To achieve this, Mercaptopropionic acid (MPA) capped CdTe QDs with superior fluorescence spectral properties grown in water medium were dispersed in PVA matrix to prepare QD-Polymer nanocomposites. Such fluorescence enriched films were stored in room temperature in ordinary environmental conditions for four years to check the degradability and viability. The stability of fluorescence and electrical properties of QDs inside PVA matrix was remarkable in this test period and were retained by the films even after such long duration. After that they were treated with UV radiation with the interval of few seconds to check the exposure recording ability of such films. The results are very promising in terms of sensitivity and the recording ability. Using the least square linear fit method a mathematical model was developed which would be useful in UV exposure sensing for smaller duration. This study also helps the concerned industries who would prepare film sensors for UV exposure quantification (like Litmus paper for pH sensing).