"Within-day and Between-day Repeatability of the Breath Pattern in Healthy Children and in Children With Moderate Asthma" is an observational prospective study in outpatient clinic of Pediatric Allergology & Pulmonology (PAP) within the Institute of Biomedicine and Molecular Immunology (IBIM) of the National Research Council (CNR) of Palermo (IBIM CNR), Italy.

The electronic nose (E-nose) has been proposed as a novel, non-invasive tool to evaluate the level of airway inflammation for different respiratory diseases, especially in children. To date, there are no data on the within-day and the between-day repeatability of the breath pattern in healthy children and in children with moderate asthma.

The breath pattern will be analyzed by collecting, for each child, three samples of the breath through the E-nose. Within-day repeatability will be assessed using two consecutive measurements (the second one after 30 minutes). Between-day repeatability will be assessed using a third measurement repeated after 7 days.

The study is expected to provide information about the accuracy of E-nose measurements for a child population.

The inclusion criteria for asthmatic children are:

1. Moderate asthma (GINA 2015);
2. Age 6-11 years;
3. No upper airway respiratory infections or exacerbations in the last 4 weeks;
4. Steroid-naive asthma;
5. Positive bronchodilator response;
6. Non smoker.

The inclusion criteria for healthy children are:

1. Age 6-11 years;
2. No upper airway respiratory infections in the last 4 weeks;
3. Non smoker;
4. No history of asthma and respiratory diseases during the life;
5. Negative bronchodilator response.

The exclusion criteria are:

1. Symptoms of acute respiratory infection;
2. Immunological and metabolic systemic disease;
3. Major malformations of the upper airways;
4. Active smoker.

A study population of 15 asthmatic children (moderate asthma) attending the outpatient clinic of Pediatric Allergology & Pulmonology (PAP) within the Institute of Biomedicine and Molecular Immunology (IBIM) of the National Research Council (CNR) of Palermo (IBIM CNR).

A control group of healthy children (n=30), recruited from the primary schools involved in the municipal project "educational pathways" (Palermo, Italy) to which the PAP group partecipates.