Cancer mortality risk from short-term PM 2.5 exposure and temporal variations in Brazil

Although some studies have found that short-term PM 2.5 exposure is associated with lung cancer deaths, its impact on other cancer sites is unclear. To answer this research question, this time -stratified case -crossover study used individual cancer death data between January 1, 2000, and December 31, 2019, extracted from the Brazilian mortality information system to quantify the associations between short-term PM 2.5 exposure and cancer mortality from 25 common cancer sites. Daily PM 2.5 concentration was aggregated at the municipality level as the key exposure. The study included a total of 34,516,120 individual death records, with the national daily mean PM 2.5 exposure 15.3 (SD 4.3) mu g/m 3 . For every 10-mu g/m 3 increase in three-day average PM 2.5 exposure, the odds ratio (OR) for all -cancer mortality was 1.04 (95% CI 1.03-1.04). Apart from all -cancer deaths, PM 2.5 exposure may impact cancers of oesophagus (1.04, 1.00-1.08), stomach (1.05, 1.02-1.08), colon -rectum (1.04, 1.01-1.06), lung (1.04, 1.02-1.06), breast (1.03, 1.00-1.06), prostate (1.07, 1.04-1.10), and leukaemia (1.05, 1.01-1.09). During the study period, acute PM 2.5 exposure contributed to an estimated 1,917,994 cancer deaths, ranging from 0 to 6,054 cases in each municipality. Though there has been a consistent downward trend in PM 2.5 -related all -cancer mortality risks from 2000 to 2019, the impact remains significant, indicating the continued importance of cancer patients avoiding PM 2.5 exposure. This nationwide study revealed a notable association between acute PM 2.5 exposure and heightened overall and site -specific cancer mortality for the first time to our best knowledge. The findings suggest the importance of considering strategies to minimize such exposure in cancer care guidelines. Environmental Implication: The 20 -year analysis of nationwide death records in Brazil revealed that heightened short-term exposure to PM 2.5 is associated with increased cancer mortality at various sites, although this association has gradually decreased over time. Despite the declining impact, the research highlights the persistent adverse effects of PM 2.5 on cancer mortality, emphasizing the importance of continued research and preventive measures to address the ongoing public health challenges posed by air pollution.