A particle detection system (10) including a particle detector (16) in fluid communication with at least two sample inlets (14, 24) for receiving a sample flow from a monitored region. The particle detector (16) includes detection means for detecting the level of particles within the sample flow and outputting a first signal indicative of the level of particles within the sample flow. A flow sensor (30) is located downstream of the sample inlets (14, 24) for measuring the flow rate of the sample flow and outputting a second signal indicative of the flow rate of the sample flow. At least a first sample inlet (34) is normally open to the monitored region for receiving at least part of the sample flow. At least a second sample inlet (36) is normally closed to the monitored region but is openable to the monitored region in response to a change in environmental conditions in the monitored region. The particle detection system (10) further includes processing means adapted for receiving the first and second signals and comparing the first signal to a predetermined threshold level and comparing the second signal to a predetermined threshold flow rate, and generating an output signal based on the respective comparisons of the first and second signals. A method of particle detection is also described.
