To more fully assess the far-reaching effects of fossil fuel combustion on humanity, it is necessary to gain an in-depth understanding of the full impact of fossil fuels on human health and lifetime potential. However, current knowledge of the long-term consequences of fossil fuel use on health damage in early life, such as human capital impacts in adulthood, is still insufficient. This paper aims to summarize the current evidence on the health effects of fossil fuel-driven air pollution and climate change on children and the consequent effect on human capital stemming from these early health damages. Evidence indicates that climate change and air pollution not only deteriorate children's health but also affect the entire human capital in their adulthood and can be deeply affected through damaged early-life health. Fossil fuel combustion can significantly impact the lifelong health and human capital for generations. We call for a more holistic assessment of the full range of impacts borne by children, including direct damages to children's health, losses of human capital, and associated economic costs. Cross-disciplinary collaboration is vital to facilitate research on such assessments, thereby enriching our understanding of the multifaceted impact of fossil fuel combustion on the early life and its long-term implications on human capital and economic potential.