My asthma keeps worsening, what to do? living in shanghai.

See a specialist: No matter where you live, it seems you need to increase (or start) a daily control medication. For "out of control asthma", an allergist or pulmonologist is the appropriate specialist.

Seek expert help: Even with big city pollution most asthmatics can be controlled with currently available medications. You need to see a well qualified allergy specialist or other asthma specialist who can evaluate your asthma, identify and treat other aggravating conditions (acid reflux, allergies, sinusitis, etc.), treat with appropriate medications (usually multiple meds required).

Asthma: When in Shanghai smog/ air pollution can be a threat to your health. I found an excellent article on many ways to protect yourself. https://www.healthandsafetyinshanghai.com/china-smog/ * Additionally, work with your doctor or a pulmonologist to address this.