Ozone is a secondary pollutant formed in the atmosphere through chemical reactions involving primary pollutants.

Catalytic converters use a chemical process to convert harmful pollutants like carbon monoxide and nitrogen oxides into less harmful substances.

Particulate filters are designed to capture and remove particulate matter from diesel engine exhaust.

Vehicle turnover refers to the natural process of replacing older vehicles with newer ones over time.

Promoting public transportation typically leads to reduced greenhouse gas emissions due to fewer vehicles on the road.

Electrification refers to the use of electricity as the primary power source for vehicles.

Catalytic converters are used to reduce harmful pollutants from gasoline engine exhaust.

Multimodal transportation involves using different modes of transportation, such as walking, cycling, public transit, and driving, to complete a single trip.

Propane is not a common alternative fuel used in vehicles, unlike electricity, hydrogen, and natural gas.

Trip reduction refers to strategies aimed at reducing the number of vehicle trips made, such as carpooling, telecommuting, and walking or cycling instead of driving.

Throttle body is not an emission control device, it is a component that controls the amount of air entering the engine.

Vehicle fuel economy refers to the distance a vehicle can travel per unit of fuel consumed.

Increasing flight altitude is not a common strategy to reduce air pollution from aviation, as it can lead to increased fuel consumption and emissions.

Intelligent transportation systems (ITS) use technology to improve traffic flow and reduce congestion.

Water vapor is not an air pollutant, it is a natural component of the atmosphere.