Dealing with fog and contaminations in environmental sensor devices

A sensor device comprising:

• a particulate matter sensor for determining at least one parameter associated with particulate matter in a sensor gas flow through the sensor device;
• a heating device configured to heat the sensor gas flow upstream of the particulate matter sensor;
• and
• a control device configured to obtain sensor signals from the particulate matter sensor, to operate the heating device to cause a variation of heating power, to determine a response of the sensor signals to the variation of heating power, and to derive an output signal based on said response of the sensor signals,
• the output signal comprising at least one of:
• a droplet indicator signal that is indicative of at least one property of evaporable droplets in the sensor gas flow;
• and
• a compensated particulate matter signal that is indicative of at least one property of particulate matter excluding evaporable droplets in the sensor gas flow.