Idling a vehicle refers to leaving the engine running when the car is not moving.  Some idling is unavoidable, but some idling is unnecessary.  While idling in traffic and other scenarios is necessary, reducing unnecessary idling helps improve air quality because idling uses more fuel and produces more emissions than stopping and restarting the vehicle.  Emissions from vehicles, especially heavy-duty vehicles, not only contribute to ozone air pollution formation, but also particulate matter pollution.  The U.S. Department of Energy estimates that up to six billion gallons of fuel are lost annually to idling of heavy-duty and light-duty vehicles, so reducing idling not only reduces emissions that contribute to air pollution, but it also conserves fuel and saves money!  Newer vehicles don’t require idling to reach ideal operating temperatures, so cars and trucks don’t need to be idled in cold weather except to defrost windows.  Newer catalytic converters, which work to reduce emissions, operate more efficiently if the vehicle is driven.  Avoiding long drive-through lines at food places and banks is another opportunity to avoid idling.  Hybrid vehicle options shut off their engines when they aren’t moving and electric vehicles don’t produce tailpipe emissions, so these are also options to reduce idling emissions.  When considering clean air strategies, think about reducing idling to reduce air pollution, while also enjoying fuel and cost savings.  For more information about idle reduction, visit https://www.nctcog.org/trans/quality/air/for-everyone/engine-off-north-texas or  https://afdc.energy.gov/conserve/idle-reduction-basics.