biostudies-literatureUnknown25(1)Lehtomaki H<h4>Background</h4>Exposure to fine particles (PM_2.5) has been associated with adverse health outcomes, even at low exposure levels (< 10 µg/m³). Burden of disease assessments can quantify these associations; however, their sensitivity to methodological choices limits comparability between studies.<h4>Methods</h4>This study aimed to quantify the impact of methodological choices on disease burden attributable to low levels of ambient PM_2.5, using Norway as a case study. Key methodological choices included (i) population exposure data, (ii) concentration-response curves, and (iii) population health data. Data from national and international sources were applied, including the global burden of disease (GBD) study. Attributable mortality and disability-adjusted life years (DALY) were estimated using burden of disease methodology. Additionally, the impact of choices related to concentration-response curves was assessed for higher exposure levels, using a scenario where exposure distributions were shifted to mean exposures up to 30 µg/m³.<h4>Results</h4>Methodological choices related to the concentration-response curves had the largest impacts on the estimated attributable deaths, ranging from - 91% to 104% change relative to the reference estimate (1,448 deaths, 95% CI 502-1497). These choices had a smaller impact on higher exposure levels, varying from - 46% to 53%. The choice of exposure and population health data led to 40% differences in attributable death estimates. DALYs attributable to PM_2.5 were predominantly driven by years of life lost (YLL: 74%). The choice of relative risk (RR) for the concentration response curve caused around 30% variation in DALY estimates relative to the reference (11,730 DALYs; 5,980 - 16,790), with larger differences for ischemic heart disease (-44 to 79%).<h4>Conclusion</h4>Attributable burden estimates for PM_2.5 are highly sensitive to key methodological choices, particularly at low exposure levels. Consequently, transparent reporting of the methodological choices and data sources in PM_2.5 health risk assessments are required to improve comparability and facilitate interpretations of the burden estimates.Environmental health : a global access science source4https://www.ebi.ac.uk/biostudies/studies/S-EPMC12802007biostudies-literatureBurden of disease attributable to PM&lt;sub&gt;2.5&lt;/sub&gt; at low exposure levels: impact of methodological choices.PMC12802007Bolling AKPereira GAasvang GMBrauer MLehtomaki HSulo GDadras ODenby BRHanninen OOfalseBurden of disease attributable to PM&lt;sub&gt;2.5&lt;/sub&gt; at low exposure levels: impact of methodological choices.<h4>Background</h4>Exposure to fine particles (PM_2.5) has been associated with adverse health outcomes, even at low exposure levels (< 10 µg/m³). Burden of disease assessments can quantify these associations; however, their sensitivity to methodological choices limits comparability between studies.<h4>Methods</h4>This study aimed to quantify the impact of methodological choices on disease burden attributable to low levels of ambient PM_2.5, using Norway as a case study. Key methodological choices included (i) population exposure data, (ii) concentration-response curves, and (iii) population health data. Data from national and international sources were applied, including the global burden of disease (GBD) study. Attributable mortality and disability-adjusted life years (DALY) were estimated using burden of disease methodology. Additionally, the impact of choices related to concentration-response curves was assessed for higher exposure levels, using a scenario where exposure distributions were shifted to mean exposures up to 30 µg/m³.<h4>Results</h4>Methodological choices related to the concentration-response curves had the largest impacts on the estimated attributable deaths, ranging from - 91% to 104% change relative to the reference estimate (1,448 deaths, 95% CI 502-1497). These choices had a smaller impact on higher exposure levels, varying from - 46% to 53%. The choice of exposure and population health data led to 40% differences in attributable death estimates. DALYs attributable to PM_2.5 were predominantly driven by years of life lost (YLL: 74%). The choice of relative risk (RR) for the concentration response curve caused around 30% variation in DALY estimates relative to the reference (11,730 DALYs; 5,980 - 16,790), with larger differences for ischemic heart disease (-44 to 79%).<h4>Conclusion</h4>Attributable burden estimates for PM_2.5 are highly sensitive to key methodological choices, particularly at low exposure levels. Consequently, transparent reporting of the methodological choices and data sources in PM_2.5 health risk assessments are required to improve comparability and facilitate interpretations of the burden estimates.2025-01-01T00:00:00Z2025 Dec2026-06-06T14:55:11.119Z2026-06-01T03:07:44.944ZS-EPMC128020074138228210.1186/s12940-025-01250-y