In an Oct. 18 letter to stakeholders, the Massachusetts Department of Environmental Protection announced changes to emissions regulations affecting medium- and heavy-duty trucks — the Heavy-duty Omnibus and Advanced Clean Truck rules.

MassDEP said it plans to file emergency regulations to delay the start of the Heavy-duty Omnibus rule until model year 2026, effective upon filing.

The department also indicated that it will exercise enforcement discretion under the Advanced Clean Truck regulation exempting state and local government vehicles used for snow plowing and removal and street sweepers for model years 2025 and 2026.