Antonicelli 1991.

Methods	Randomised cross‐over study
Participants	9 participants aged 10 to 28 years with either allergic rhinitis or asthma
Interventions	Using an air‐cleaning device equipped with HEPA
Outcomes	House dust mite (Der p1, Der f1 and Der m1) allergen level Rhinitis and asthma symptom score
Notes	—
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation?	Unclear risk	"Patients were randomly divided into two groups of five and four subjects in each" The use of random sequences is not stated
Allocation concealment?	Unclear risk	Insufficient information
Blinding?	High risk	No blinding of participants or investigators
Incomplete outcome data addressed? All outcomes	Low risk	No evidence of incomplete data
Free of selective reporting?	Low risk	No evidence of selective reporting
Free of other bias?	High risk	Very small study group