The article explores how carbon trading plans can be more effective by including only certain industrial sites instead of all of them. They suggest that opting for a selective approach could help lower the high expenses linked to managing these programs. By studying data from the EU's trading scheme, they find that covering every installation can be more expensive than focusing on specific sectors and sites. In simpler terms, being choosy about which factories are part of these emission trading systems can lead to better cost savings and environmental benefits.