This is a single centre randomised, placebo-controlled phase 2 study in which 96 children age 4 to 16 years with moderate to severe, longstanding allergic eczema will be enrolled.

Following a 4 to 6 week period on standardised treatment (run-in period, to ensure everyone starts with the same treatment approach), participants will be randomised to an active or dummy temperature-controlled laminar airflow (TLA) device, which has been shown to markedly reduce exposure to particles which can cause allergic reactions when being inhaled (inhaled allergens) and other particles which are in the air the investigators breathe in. This has been shown to be an effective treatment of atopic asthma.

The participants will undergo a 12-week treatment period. The device will then be removed and a final follow-up visit occurs at 16 weeks. The total study duration, including the run-in period is up to 22 weeks.

Inclusion Criteria:

• Age 4 to 16 years at time of consent
• Persistent moderate to severe eczema despite treatment with topical corticosteroids (TCS) Class II or more and/or topical calcineurin inhibitors (TCI, licenced use only) for at least 3 months.
• Eczema Area and Severity Index (EASI) Score ≥12 at screening and randomisation visit and >10% body surface involved
• Sensitisation to house dust mite species, confirmed by specific Immunoglobulin E (ImmunoCAP ≥2) and/or Skin Prick Test (SPT ≥5mm)
• Child able to sleep in their own bed and able to use the device for at least 5 out of 7 nights per week
• Written, informed consent of parent/legal guardian and patient assent

Exclusion Criteria:

• very severe atopic dermatitis
• use of systemic immunosuppression (such as cyclosporine, methotrexate, azathioprine, oral steroids) or UV therapy or extracorporal photopheresis within four weeks prior to the screening visit
• received therapeutic monoclonal antibodies (such as Omalizumab or Dupilumab) within six months prior to the screening visit
• Ongoing or planned desensitisation / immunotherapy during the study
• Infections requiring systemic antimicrobial treatment within four weeks prior to the screening visit
• Introduction of special dietary restriction (for eczema treatment) within three months prior to screening visit
• Severe asthma ≥ Step 4 and/or ≥1 course of systemic oral steroids for asthma in the three months prior to screening visit
• Significant underlying chronic medical condition (chronic other skin disease, inflammatory bowel disease, immunodeficiencies, other uncontrolled systemic disease, cancer)
• Planned time away from home (=unable to use TLA) exceeding 2 days/week; unable to use the device at least 5/7 days in the 2-3 weeks prior to end of intervention period.
• Prior research participation is not an exclusion criterion, except if it involved eczema disease modifying agents.
• Participating in current research