As Seattle seeks to battle air pollution, Mayor Jenny Durkan has suggested instituting a toll on motorists who traverse streets in the crowded downtown area. The proposal is one of 12 different recommendations designed to curb the emission of greenhouse gases in Seattle.

Seattle took the first big step towards decreasing air pollution in 2011 when then-Mayor Michael McGinn and the Seattle City Council pledged to slash emissions 58% by 2030 and become completely carbon neutral by 2050. The city officially adopted a comprehensive Climate Action Plan in June 2013. As part of the plan, Seattle’s Office of Sustainability and Environment studied the best ways to cut emissions, recommending the expansion of bus corridors and the addition of biking lanes and racks for bicyclists. The city also launched a campaign to encourage ridesharing and bike sharing.

Mayor Durkan has devised the new plan in response to the slow progress of the city’s Climate Action Plan. Although many of the plan’s goals have been achieved, greenhouse gas emissions have only declined by 6% in the last 10 years. Furthermore, carbon emissions per capita have declined by only 17%, leaving the city lagging behind in its goal to become carbon neutral by 2050.

As part of the new initiative, the city may consider implementing congestion pricing in downtown Seattle. The Seattle Department of Transportation is currently researching a possible toll for motorists traveling through the $2.2. billion Highway 99 Tunnel, tentatively scheduled to officially open in October.

In addition to charging city motorists, the mayor has also proposed expanding the city’s electric vehicle infrastructure, electrifying taxis and adding additional charging stations for electric vehicles. Seattle will also transition official city vehicles over to electric vehicles. Under the plan, the city will offer building owners incentives to reduce energy and water usage on their properties.