A single use sterile slit impact sampling cassette with rotatable capture tray for recovering particulate matter from ambient air, having a lid with a slit shaped air inlet, dish with an air outlet, and capture tray. The dish and lid assemble to form a sealed sample chamber, which houses the capture tray. The assembled cassette is sterile packaged with its inlet and outlet covered before use. The cassette is placed on a base for operation, which supplies the required vacuum for sampling, and rotational means for the capture tray. Air drawn into the air inlet is accelerated to a velocity that ensures impingement, or entrainment of particulate matter from the sampled air volume onto, or within the capture media. The sampled air volume is evacuated from the sample chamber through an air outlet. The cassette is then removed from the operative base, and then may be analyzed for the target contaminants.