Which of the following practices helps reduce urban air pollution?

Promoting carpooling and bike lanes is an effective practice for reducing urban air pollution because it decreases the number of vehicles on the road. Fewer vehicles result in lower greenhouse gas emissions and reduce the overall concentration of pollutants such as nitrogen oxides, carbon monoxide, and particulate matter in the air. Carpooling allows multiple people to share a ride, which decreases traffic congestion and emissions per person. Similarly, bike lanes encourage cycling as a viable mode of transportation, promoting an environmentally friendly alternative to driving. This shift from personal vehicles to shared or non-motorized transport leads to cleaner air and contributes to improved public health outcomes by reducing the risk of respiratory and cardiovascular diseases associated with air pollution.

In contrast, the other practices listed do not contribute positively to air quality. Expanding coal use in energy production increases air pollution significantly, as coal burning releases a substantial amount of sulfur dioxide and particulate matter. Building more highways tends to promote the use of personal vehicles and can lead to increased traffic and pollution rather than alleviating it. While high-density surveillance cameras may enhance security, they do not directly address or mitigate air pollution concerns.