# The declining but persistent burden of lower respiratory infections from secondhand smoke in children aged under 14 years: Global trends 1990–2021 and forecasts to 2035, based on a secondary dataset analysis of Global Burden of Disease (GBD) 2021

## TL;DR

Secondhand smoke still causes lung infections in children, but the global impact is expected to decline through 2035.

## Contribution

First systematic global analysis of LRI burden from SHS in children under 14, with forecasts to 2035.

## Key findings

- In 2021, SHS caused 2.25 deaths and 199.84 DALYs per 100,000 children under 14 globally.
- Global mortality and DALY rates from SHS-related LRIs are projected to decline further by 2035.
- SHS remains a significant risk factor for LRIs in children despite overall declining trends.

## Abstract

Although global smoke-free policies have significantly reduced smoking rates, exposure to secondhand smoke (SHS) in homes and public places remains common. SHS continues to be a significant risk factor for lower respiratory infections (LRIs) in children. However, there is still a lack of systematic assessment of the spatiotemporal trends and future disease burden of LRIs attributable to SHS in children aged under 14 years.

This study is a secondary analysis of the Global Burden of Disease (GBD) 2021 data. We used joinpoint regression to analyze trends and calculate the average annual percentage change (AAPC) in the burden of LRIs attributable to SHS among children aged under 14 years, globally from 1990 to 2021. Age-standardized rates (ASRs) of mortality and DALYs were quantified at the global, regional, and national levels. Finally, a Bayesian age-period-cohort (BAPC) model was applied to forecast trends up to 2035, providing a basis for formulating targeted intervention strategies.

In 2021, the number of deaths and disability-adjusted life years (DALYs) among children aged under 14 years worldwide due to LRIs caused by SHS decreased significantly. The ASR declined to 2.25 (95% UI: 0.73–3.86) for mortality and 199.84 (95% UI: 64.82–342.97) for DALYs per 100000 population. The forecast results indicated that by 2035, both the mortality and the DALY rates would continue to decline.

Although the global burden had declined significantly and was expected to continue decreasing through 2035, SHS remained a significant contributor to LRIs in children.