Single-center, interventional, open-label, randomized phase II study aimed at describing the changes in airway inflammation at the onset of asthma symptoms that lead to the use of rapid acting bronchodilator (RABD) as a rescue medication in a mild to moderate asthma population. The study will assess whether there are differences in the airway inflammation profile in patients using a reliever medication containing ICS (anti-inflammatory rescue strategy) compared to a reliever medication containing only a bronchodilator for symptom relief (Non anti-inflammatory rescue strategy).

The study is structured into two distinct and separate phases, an observational and an interventional.

- Phase 1: Observational Phase The observational component of the study aims to describe the variations in airway inflammation at the onset of asthma symptoms when patients (n=50) are under the appropriate anti-asthma therapy (Standard Of Care, SOC), which includes a rapid-onset bronchodilator (RABD) as needed. The RABD used may be either salbutamol or formoterol, depending on the therapeutic strategy employed by the patient and the GINA Track followed.

Before and after taking the SOC rescue medication, the patient will measure markers of airway inflammation and clinical impact (FeNO, FEV1, PEF, VAS scale) using the "PEFESP kit" provided to each enrolled patient. They will record these values in the "patient diary" for the subsequent 48 hours.

- Phase 2: Interventional Phase In a crossover design according to the AB/BA scheme, it will be assessed whether there are differences in the airway inflammation profile in patients (n=30) using a reliever medication containing ICS compared to a reliever medication containing only a bronchodilator.

The interventional phase consists of two open-label monitoring phases, each lasting a maximum of 3 weeks, separated by a washout period of 3 to 7 days and for a maximum of 3 symptom episodes. As in the observational part, patients will be asked to record the markers of airway inflammation and the clinical impact of symptoms at the onset of the change from stable condition and in the 48 hours following the administration of the reliever medication.

Patient with mild asthma will be the first group of severity enrolled in the study.

Inclusion Criteria:

• Patients already followed for asthma according to ERS/ATS criteria
• Mild and moderate asthma (GINA steps 1-3), with the exclusion of patients with severe asthma (GINA steps 4-5).

Exclusion Criteria:

Severe asthma (Gina steps 4 and 5)

• Inability to give informed consent
• Diagnosis of other clinically significant respiratory diseases
• Diagnosis of Chronic Obstructive Pulmonary Disease (COPD)
• History of smoking: > 10 pack/year or stop for less than 3 months
• Oral steroid therapy in the 2 months prior to enrollment
• Number of asthma exacerbations per year ≥ 2
• Pregnancy
• Evidence of clinically significant pathologies other than in respiratory system (i.e., cardiovascular, hepatic, renal, nervous, endocrinological, oncological, dermatological systems)