Under the proposed rules, vehicles will be categorized into four groups based on registration dates (Pre-2056, 2056–2069, 2069–2082, and Post-2082). While limits for older vehicles will be relaxed, newly registered vehicles (post-2082) will face significantly stricter pollution caps.
Petrol vehicles will be tested for carbon monoxide, hydrocarbons, and 'lambda' (air-fuel ratio); diesel vehicles for smoke opacity; and CNG/LPG vehicles for hydrocarbons using new testing methods. Meanhwhile, construction equipment (tractors, dozers, excavators) and military vehicles are exempt.
The rules will come into force 91 days after publication in the Nepal Gazette, with immediate strict enforcement planned for diesel vehicles nationwide and across metropolitan and sub-metropolitan cities, including the Kathmandu Valley. The government expects the move to push owners of older, high-emission vehicles to repair or replace them.
