The document discusses London's Non-Road Mobile Machinery (NRMM) Low Emission Zone, which aims to reduce emissions from construction machinery. It has led to measured reductions of 48% for PM10 and PM2.5, and 42% for NOx, compared to baseline levels. The zone requires machinery above 37kW to meet certain emission standards, and sites must register their machinery online. Compliance is enforced through on-site inspections. The standards have tightened over time and will require newer Stage V machines by 2023. The program has seen little industry pushback and provides a model that could be applied in other cities.