CHENNAI: A 26-year-old man died of asphyxiation while another has been hospitalised after inhaling toxic fumes while clearing an underground drainage of CMWSSB in Madhavaram on Tuesday. The deceased Nelson (26), from Tirunelveli was employed by a private firm, undertaking cleaning contracts. On Tuesday, Nelson along with Ravikumar (40), from Thanjavur were sent to Mariamman Koil Street in Madhavaram after complaints of sewage overflow. The incident happened around 4 pm. Police sources said that Nelson, who got down to clear the drainage fainted and Ravikumar who followed him too became unconscious. The duo were moved to the Government Stanley hospital, where Nelson was declared brought dead. Madhavaram police registered a case. Two persons, Prakash (53) and Vinish (33), a supervisor have been detained.