EMPLOYEE WAS PERFORMING RISER CLEANING IN THE PREHEATER TOWER WITH A CO-WORKER. THE CO-WORKER HAD REQUIRED PROTECTIVE EQUIPMENT BUT EE DID NOT WEAR HIS. EE OPENED A PORT AND THEN MANUALLY FIRE D AN AIR CANNON WHICH BLEW HOT DUST ON HIM. HE VIOLATED EVERY SAFETY RULE IN THE JOB FOR TOWER CLEANING.