1. shut down the factory
This is a suggestion that will not be implemented simply due to the fact that the factory is likely to be bringing profits and meeting the requirements of a specific product or products. Shutting the factory down will mean great losses, which makes this suggestion non-feasible.
2. Move the factory out of the city
First, "moving" a factory is not as easy as it sounds. For a factory to be set up, many factors are considered such as the availability of raw materials and transport cost. Moreover, the emissions will still not be lessened if the factory is simply moved.
3. Increase the height of the factory's chimney
If these emissions are harming the nearby environment, this suggestion will help to reduce those effects. However, the negative effects will inevitably occur if there is a high level of emission of sulfur dioxide occurring, such as acid rain. Therefore, this does not solve the problem, only changes its nature.