Carbon-dioxide is one of the most abundant gasses in the atmosphere. Due to human induced anthropogenic activities, the amount of CO2 released into the atmosphere has been rising extensively during the last 150 years. Present investigation was carried out to assess the carbon dioxide concentration in ambient air of Tarai region of Uttarakhand. The online monitoring of CO2 concentration from ambient air was carried out with the help of a Non-dispersive Infra-red (NDIR) gas analyzer at one minute time interval. Simultaneously, air samples were collected from various sampling sites...