This registration has been updated. Please see the updated systematic review protocol registration at https://doi.org/10.17605/OSF.IO/KMTQA. An increasing number of epidemiology studies have been conducted to examine the relationship between indoor nitrogen dioxide exposure and childhood asthma or wheeze. However, the previous systematic review on this topic, which was conducted about a decade ago, did not sufficiently evaluate heterogeneity among individual studies or study quality. We propose to conduct a new systematic review on the association between indoor nitrogen dioxide or gas cooking and asthma or wheeze in children that entails an in-depth evaluation of study heterogeneity and study quality and covers the recently published literature.
