Vehicles that were owned or leased by Boston or used by its contractors will need to be retrofitted with emissions reduction equipment under an ordinance signed Wednesday by Boston Mayor Marty Walsh.

The ordinance, filed by City Councilor Stephen Murphy, was hailed for its potential to reduce air pollution and its negative impacts, particularly on communities of color in the city. “The asthma rate in Boston’s neighborhoods continues to climb,” Murphy said in a statement. “By further tightening air quality standards, as this ordinance does, we will make Boston’s neighborhoods healthier."

According to Walsh's office, most of the city's diesel school buses are newer and have built-in pollution reduction equipment, or have been retrofitted already. The city plans to complete work on 75 city vehicles requiring retrofits under the ordinance by the end of this year. Requirements for diesel vehicles and equipment used on new city contracts over $2 million will be phased in over three years.

The ordinance also addresses the authority for the Boston Police Department, Transportation Department and the Air Pollution Control Commission to enforce "in a consistent way" a limit on unnecessary idling of five minutes. Fines for violation of the idling rules will be $100 for the first offense and $500 for subsequent offenses.