Smog is a big problem in many Chinese cities. But it seems that besides wearing a mask, few of us know what has caused the smog and what to do to beat it. Chai Jing, a former news interviewer with CCTV, discussed the questions in her documentary Under the Dome. The 103-minute film was on websites on Feb 28. In the film, Chai visits polluted places and talks to officials and scientists. She thinks that burning too much coal and oil are the main causes of PM2.5 and smog. To solve the problem, Chai suggests that we should clean our coal and oil or replace them with cleaner energy such as natural gas. In her film, Chai also emphasized   that everyone can do something to help control smog too. For example, we can live a greener life by using more public transport. Or if we see things that could harm the environment, we can try to stop it. In the film, when she sees a restaurant cooking without any suitable filter facilities  , she calls the hotline 12369. The restaurant installed the filter a week later. Chen Jining, the new minister of environmental protection, praised Chai. "This film encourages ordinary people to take notice of the environment. This is what we need in the future." Which of the following is NOT included in Chai's suggestions towards reducing smog?
Using cleaner energy. Cleaning coal and oil. Using public transport. Replacing coal with wind energy.