BackgroundEpidemiological trends of lower respiratory infections (LRIs) attributable to secondhand smoke (SHS) among children under 5 years since smoking bans have been increasingly applied globally remain unclear. Here, we aimed to estimate the spatiotemporal trends of the global, regional, and national burden of LRIs attributable to SHS among children under 5 years old between 2010 and 2019.MethodsData on the deaths, and disability adjusted life years (DALYs) of the disease burden was retrieved from the Global Burden of Disease (GBD) 2019 for 204 countries and territories between 2010 and 2019. The rates per 100,000 population, along with 95% uncertainty intervals, as well as population-attributable fraction (PAF) was presented for each estimate.ResultsIn 2019, an estimated 6.94% (3.80–10.12%) of under-5 LRIs deaths were attributable to SHS globally, with an under-5 mortality rate of 7.02 per 100,000, a decrease of 5.77% since 2010. Similarly, 6.95% (3.81–10.13%) of LRIs DALYs were due to SHS among children under 5 years, with a rate in under-5s of 619.36 DALYs per 100,000, and also a 5.77% decrease since 2010. Azerbaijan, Turkmenistan, and Papua New Guinea showed the highest under-5 mortality and DALYs burden rates of LRIs attributable to SHS in 2019. In contrast, the PAF was stagnant over the past ten years and there is even a year-on-year upward trend in South Asia. Nationally, in 2019, Bosnia and Herzegovina, Armenia, and Montenegro showed the highest PAFSHS of LRIs burden among children under 5 years of age. In addition, the burden was heavier in children under 1 year of age and was significantly negatively associated with sociodemographic index.ConclusionsSHS remains a risk factor that cannot be ignored for LRIs burden worldwide. Hence, governments and health systems should continue to take steps to reduce SHS pollution among young children to mitigate this burden.