Can outdoor, cold air help improve moderate croup symptoms in children?


Investigators of a study published in Pediatrics examined whether a 30-minute exposure to outdoor air (< 50 °F) would improve symptoms of mild to moderate croup.

Can outdoor, cold air help improve moderate croup symptoms in children? | Image Credit: © lexiconimages - © lexiconimages -

Can outdoor, cold air help improve moderate croup symptoms in children? | Image Credit: © lexiconimages - © lexiconimages -

As an adjunct to oral dexamethasone, a 30-minute exposure to outdoor cold air that is less than 50 °F (10 °C) can be beneficial in reducing clinical symptoms of croup in children, according to a study published in Pediatrics.

Acute viral laryngotracheitis or laryngotracheobronchitis, also known as croup, is the most common cause of acute upper airway obstruction, typically in children from 6 months to 3 years in age, across varying degrees of severity. Croup makes up 3% to 5% of annual pediatric emergency department (PED) visits and readmissions in children younger than 2 years. Nonspecific prodromal upper respiratory tract symptoms and low-grade fever can occur before the onset of a predominantly nocturnal and distinctive cough, for which croup is characterized.

According to the study authors, cold air exposure is reported to benefit children in day-to-day practice by parents, though data to document evidence is lacking. As a result, investigators conducted a prospective, single-center, open-label, randomized controlled trial at a tertiary PED to compare the efficacy of a 30-minute cold, outdoor, atmospheric air exposure to ambient, indoor, room-temperature air. Correlating with the highest prevalence of parainfluenza virus, the study was conducted during cold days and nights during late fall to spring. The trial (NCT05668364) was registered under the Swiss National Clinical Trials Portal.

Children were eligible for study inclusion if they were 3 months to 10 years of age and presenting to the PED. Written informed consent, outdoor cold air temperatures less than 50 °F, and a Westley Croup Score (WCS) of 2 or greater were inclusion requirements. At the start of the trial, WCS was calculated, ranging from 0 to 17. Upon PED arrival, patients were triaged and if outdoor temperatures were sufficient, individuals were offered participation. A single dose of 0.6 mg/kg oral dexamethasone was administered before participants were assigned randomly to wait outside of the PED but in sight of the triage desk. Those exposed to the outdoor cold air were offered blankets. The other participants waited inside the PED, where ambient air was pulsed at 75.2 °F to 77 °F (24°C to 25 °C).

Those in the outdoor group were immediately assessed upon return to the PED after the 30-minute expose. Outside time was documented if the participants returned before the 30-minute timeframe, though a minimum of 15 minutes outside was considered valid. WCS was assessed again at 30 and 60 minutes after triage and patients were discharged when deemed clinically appropriate. The primary outcome was the proportion of patients showing clinical improvement defined as a 2 point or more WCS decrease from baseline at 30 minutes. According to the study, a single dose of oral dexamethasone has demonstrated benefits 30 minutes after administration, allowing investigators to assess the effect of cold air in this timeframe.

Between November 1, 2016, to May 31, 2021, 1505 patients presented to the PED with croup were assessed for eligibility for this study. In total, 118 children were randomly assigned to an outdoor cold air exposure (n = 59) or indoor room temperatures (n= 59). For patients in the outdoor group, 49.2% (n = 29) showed a decrease in WCS of 2 or more points at 30 minutes compared to baseline, whereas 23.7% (n = 14) of the indoor group patients showed a decrease in WCS of 2 or more points (risk difference 25.4% [95% CI, 7.0-43.9], P = .007]). Benefiting most from the outdoor group were children with moderate croup at 30 minutes (risk difference 46.1% [20.6-71.5, P < .001]).

As an adjunct to oral dexamethasone, a 30-minute outdoor cold air exposure in temperatures lower than 50 degrees Fahrenheit was beneficial in reducing the intensity of croup’s clinical symptoms. Authors noted further studies are needed to assess cold air exposure efficacy and perspectives include the use of digital auscultation, coupled with the blinding of the clinical assessment to reinforce the findings of the study.


Siebert JN, Salomon C, Taddeo I, Gervaix A, Combescure C, Lacroix L. Outdoor cold air versus room temperature exposure for croup symptoms: A randomized controlled trial. Pediatrics 2023; e2023061365. 10.1542/peds.2023-061365

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