Study	Reason for exclusion
Anah 1980	Not restricted to children (≤ 18 years). The average age of participants was 27.1 years. Also did not specifically address problems associated with school return.
Bruce 1977	Not restricted to children (≤ 18 years). Sample group selected from adult volunteers. Also relates to the ragweed season rather than specifically addressing school return.
Bueving 2004	Incorrect seasonal focus. Children participated during influenza season. Study lacks specific purpose of reducing school‐return exacerbations of asthma.
Busse 2011	Incorrect methodology. Exacerbations after school return were reported as an outcome, but this was a post hoc analysis. The study was not a randomised controlled trial of an intervention specifically designed to reduce exacerbations after school return.
Coffman 1971	Does not refer to asthma and incorrect seasonal focus. Study refers to hay fever grass pollen allergy during the summer months between May and July.
Corren 1992	Study not restricted to children (≤ 18 years). Mean age for placebo group was 35.1 years. Mean age for nasal beclomethasone dipropionate group was 36.1 years. Also study was designed to reduce asthma and rhinitis symptoms during the autumn pollen season rather than addressing the problem of school return.
Crane 1998	No mention of seasonal exacerbations of asthma
Engstrom 1970	Incorrect seasonal focus. Main seasons of symptomatology extended from May to August.
Esquivel 2016	No mention of seasonal exacerbations of asthma. This study examined data from the Preventative Omalizumab or Step‐up Therapy for Severe Fall Exacerbations (PROSE) study reported in Teach 2015a but considered 'colds' as the outcome.
Fang 2001	Not limited to children (≤ 18 years). Mean age was 37 years. Also intervention not specifically designed to reduce exacerbations after school return.
Ford 1969a	Not restricted to children (≤ 18 years). All but one participant older than 30 years. Also intervention not specifically designed to reduce exacerbations after school return.
Ford 1969b	Incorrect seasonal focus, referred to pollinotic asthma in the height of spring
Gerald 2012	Incorrect methodology. Purpose was not to compare intervention designed to reduce school‐return exacerbations of asthma with usual care. Randomised controlled cross‐over trial of year‐round hand sanitiser compared to normal hand hygiene
Grant 1995	Not restricted to children (≤ 18 years). Aged 12 to 70 years. Also intervention not specifically designed to reduce exacerbations after school return but rather to prevent exacerbations associated with the pollen season.
Halterman 2002	No mention of seasonal exacerbations of asthma
Halterman 2004	No mention of seasonal exacerbations of asthma
Halterman 2005	No mention of seasonal exacerbations of asthma
Joseph 2005	No mention of seasonal exacerbations of asthma
Levy 2006	No mention of seasonal exacerbations of asthma
Lewis 2012	No mention of seasonal exacerbations of asthma
Prazma 2015	Purpose was not to compare intervention designed to reduce school‐return exacerbations of asthma with usual care. Compared fluticasone propionate/salmeterol to fluticasone propionate rather than a usual care control.
Yoshihara 2014	Purpose was not to compare intervention designed to reduce school‐return exacerbations of asthma with usual care. Compared suplatast tosilate to mequitazine rather than to a usual care control.