To make cities cleaner as they grow in population and industrial activity, it is essential to implement effective strategies. Here are a few ideas:

1. **Increase Public Transportation Options**: Cities should invest in efficient public transport systems, such as buses, subways, and trams. By encouraging people to use public transportation instead of cars, we could reduce traffic congestion and air pollution significantly.

2. **Promote Green Spaces**: Urban areas should include more parks and green spaces. Not only do trees and plants improve air quality, but they also provide recreational areas for residents. Local governments could initiate tree-planting campaigns and maintain existing parks to promote a cleaner environment.

3. **Implement Strict Waste Management Policies**: Cities could adopt stricter regulations on waste management. This includes enforcing recycling programs and reducing the use of single-use plastics. Residents should be educated on the importance of proper waste segregation and recycling practices.

4. **Encourage Sustainable Practices**: People should be encouraged to adopt eco-friendly habits like composting, using biodegradable materials, and participating in local clean-up events. By raising awareness about sustainability, we could foster a community that prioritizes cleanliness and environmental responsibility.

5. **Utilize Technology for Cleanliness Monitoring**: Cities could leverage technology by using apps to report littering or waste disposal issues. Citizens should be encouraged to participate actively in keeping their neighborhoods clean, and local authorities could respond quickly to these reports.

In my opinion, a combination of these strategies is necessary for making cities cleaner. It is crucial to engage the community in these efforts and ensure that people see the direct benefits of living in a cleaner environment.