Evidence Driven Indoor Air Quality Improvement

Inclusion Criteria: * school aged participants with asthma (patients with a clinical diagnosis of asthma (according to European Respiratory Society (ERS) and American Thoracic Society (ATS) guidelines) for at least a year , being on a stable dose of anti-inflammatory treatment for at least one month with partially controlled or uncontrolled asthma according to GINA guidelines) * non-asthmatic school aged participants (matching control subjects) * signed informed consent, . * additional inclusion criteria include clinically significant allergy to indoor and outdoor allergens, with positive skin prick test (SPT) and specific IgE levels (\>0.7 kUA/L) (UA = allergen-specific unit) Exclusion Criteria: * known inborn or perinatal pulmonary disease; * pulmonary malformation; * oxygen therapy after birth with a duration of more than 24h; * ventilator support or mechanical ventilation after birth; * diagnosis of cystic fibrosis; * primary ciliary dyskinesia; * heart failure diagnosed after birth affecting pulmonary circulation; * major respiratory diseases such as e.g. interstitial lung disease, * acute respiratory infection at recruitment, * use of systemic corticosteroids, * recent asthma-related visit to emergency department (in the past three weeks) * coexistence of other serious chronic illness. Moreover, children will be excluded from study visits and biomaterial collection in the case of fever of at least 38.5°C during the last two weeks prior to the planned visit.