A sampler apparatus (200) is disclosed. The sampler apparatus (200) comprises an impactor assembly (202) comprising a nozzle plate (206), an impaction plate (208), and a filter unit. The nozzle plate (206) comprises a plurality of nozzles for channelling an air stream through the sampler apparatus (200). The impaction plate (208) is adapted to collect particulate matter having size equal to or greater than a threshold size. The filter unit (210) is adapted to collect particulate matter having size less than or equal to the threshold size. The sampler apparatus (200) further comprises a control assembly (204) coupled with the impactor assembly (202). The control assembly (204) comprises one or more flow control devices (218) to maintain a predetermined air-flow rate of the air stream within the sampler apparatus (200).