An electronic device is proposed for accompanying a perishable good during one period to monitor the exposure of the good to an environmental parameter, such as temperature. The device includes a data interface for receiving data representing the exposure of the good to the environmental parameter during an immediately preceding period. It further includes a sensor for measuring the environmental parameter. Also, the device includes a processor for using a relationship specific to the good (such an Arrhenius equation for that good) to compute a characteristic of the good at the end of the one period using the received data and the output of the sensor. The device further includes a memory for recording the output of the sensor. To economise on memory usage, data is stored at a faster rate during periods when the data is of most significant (e.g. it indicates a high temperature). A switch is provided for indicating that data should not be taken into account in the computation, during a short interval, in which for example the device may be being handled.