Progress to severe inflammation and spasm and chronic states can be slowed down. The first rule is to get rid of anything that will make breathing difficult. Good air-conditioning filters pollen and dust. Plastic liners over mattresses and double casing pillows reduce mite reactions. Frequent painting of home walls reduces exposure to roach saliva.
Pets can be a real problem.
Animal hair and dander, ticks, plant pollen, dust are all brought to bear when a pet causes a breathing crisis. Some say daily bathing of the pet can markedly reduce the danger beloved pets can cause. Others recommend outside pets only, or no pets. I strongly favor no pets if there is any evidence of a person with asthma reacting with even mild breathing problems in the presence of a pet. Many asthmatics smoke or are engulfed in smoke in their own household.