Nebulizer treatments are often used for those with asthma, especially for children or those without access to an inhaler. Treatment involves wearing a mask that goes over your mouth and nose that delivers a thin mist of medication incorporated into the oxygen. The mist includes albuterol and sometimes ipratropium bromide which can help relax the muscles that control your airway and as a result making it easier to breathe.
Sources:
American College of Allergy, Asthma, and Immunology (acaai.org)
The American Academy of Allergy, Asthma & Immunology | AAAAI