Heat, air pollution, and learning loss: global impacts on educational equity and human capital formation

Environmental stressors such as heat and air pollution are increasingly recognized as critical dimensions of climate risk, with implications that extend beyond health to educational performance and long-term economic development. This study examines the global association between chronic exposure to heat stress and fine particulate matter (PM2.5) and student learning outcomes, using harmonized exam data from the OECD Programme for International Student Assessment spanning 59 countries from 2000 to 2018. The sample covers a diverse range of low-, middle-, and high-income contexts, enabling a globally comparative analysis. We construct seasonal exposure metrics aligned with school calendars, using Wet Bulb Globe Temperature (WBGT) to more accurately capture thermal stress in humid environments. We find that a 1 °C increase in WBGTmax during school months is associated with a −0.0625 standard deviation (SD) decline in test scores—substantially larger than estimates based on annual averages. PM2.5 is likewise associated with lower student performance, and when combined with high pollution levels (>55 µ g m −3 ), the association with heat is amplified: the marginal effect per additional 1 °C increases from −0.047 to −0.076 SD, reflecting a stronger association under dual exposure. Students in low-and middle-income countries show estimated learning losses more than twice as large as their peers in high-income countries. Under current conditions, these results correspond, in illustrative terms, to learning losses of up to 5.5 months, increasing to 7.5 months under a +2.5 °C warming scenario. These estimates represent illustrative, scenario-based projections of potential human-capital implications, including possible lifetime earnings losses ranging from 1.6%–3.2% under maintained conversion assumptions, with the steepest burdens falling on countries least equipped to adapt. Our findings highlight that safeguarding learning may need to become a core element of climate adaptation planning, requiring the integration of resilience measures into education policy and infrastructure investments to protect human capital in a warming world.