The overlooked global reach of wildfire smoke: beyond local health and cancer risk

We read with interest the recent Comment by Weichenthal (Weichenthal, S. We cannot ignore the cancer risks of wildfires. Nat. Rev. Cancer 25, 219–220 (2025))¹, which highlighted the carcinogenic risks associated with recurrent wildfires and the pressing need for public health action. We agree that wildfires are not only a local environmental issue but a growing global health crisis. However, we would like to emphasize that the geographic scope of their impact is even broader than previously discussed, with substantial consequences for public health not only in regions where the fires occur but also in areas located far from the fire epicentres, owing to long-range smoke transport.

Wildfires in the Amazon and across the African continent have not only devastated ecosystems locally but have also affected distant communities through atmospheric smoke transport^2,3. Observational data show that smoke from African fires can reach the Amazon basin, and fires in the Amazon, located in northern Brazil, and the Brazilian Pantanal have darkened skies and worsened air quality in Ceará, a state in northeastern Brazil⁴. These events are not isolated; they reflect a concerning interregional and transcontinental pattern of smoke transport with profound implications.