Final answer:
The WHO estimates that over half of the deaths due to indoor air pollution occur in children under the age of 5, with exposure to pollution from solid fuels in the household being a major factor.
Step-by-step explanation:
The World Health Organization estimates that over half of the deaths worldwide due to indoor air pollution are among children under the age of 5. Exposure to pollutants from the indoor use of solid fuels for cooking and heating in households is a significant contributor to respiratory infections and diseases. These health issues are particularly acute in developing countries, where such fuels are commonly used, and where women and children spend considerable time indoors and are thus frequently exposed to these harmful pollutants. High levels of indoor air pollution are responsible for the death of millions, surpassing the number of deaths from outdoor air pollution, and they significantly affect sensitive groups, including children with still-developing respiratory systems.