Public participation is important for managing conflicts related to the environment. A study compared Shanghai and Hong Kong to see how public involvement affects NIMBY conflicts. The results showed that who is involved, how much they participate, and when they participate all make a difference. In both places, there was no public involvement during the planning stage. In China, certain types of participation and late involvement had negative effects on public acceptance of NIMBY facilities. To manage these conflicts better, it's suggested to involve key stakeholders, increase participation, use specific approaches, and involve the public at the right times.