During Enmasse Coolant Channel Replacement (EMCCR) operation at Unit - I of MAPS, air and air particulates samples were collected from south and north F/M vault of Unit #1. Swipe samples from the surface of coolant channels were also collected. Air samples were analysed for ¹⁴Cactivity. Air particulates samples and swipe samples were analysed for ¹⁴C, ^23SPu, ^239+240Pu, ²⁴¹Am, ²⁴²Cm and ²⁴⁴Cm. The concentration of different radionuclides present in the air particulates were found to be insignificant and are comparable to the values observed during EMCCR operations carried out at Unit-2 of RAPS and Unit-2 of MAPS. The activity ratios in both air particulates and swipe were similar indicating that the source of airborne radloactivity was from the surface of the coolant channels being removed,