Population Size, Background Disease Burden, and Ozone Exposure as Drivers of Ozone-Attributable Chronic Obstructive Pulmonary Disease Mortality, 1990–2023: A Das Gupta Decomposition of Global Burden of Disease 2023 Data

Background: Long-term exposure to ambient ozone is an established cause of chronic obstructive pulmonary disease (COPD) mortality. Absolute ozone-attributable COPD deaths have risen sharply since 1990, but the separate contributions of changing ozone exposure, changing population size, and changing background COPD mortality have not been quantified.Methods. Using Global Burden of Disease Study 2023 estimates for 204 countries, we expressed ozone-attributable COPD deaths as the product of the population-attributable fraction, the background COPD death rate, and population size, and decomposed the 1990–2023 change into three exactly additive components using the Das Gupta (1993) three-factor method. We additionally estimated a counterfactual in which the population-attributable fraction remained at its 1990 value. Reconstructed totals were validated against the published GBD global estimate before analysis.Results. Global ozone-attributable COPD deaths rose from 172,584 (95% uncertainty interval 39,323–329,062) in 1990 to 468,719 (108,209–854,387) in 2023, an increase of 171.6%. The three drivers contributed almost equally: population size +113,103 deaths (38.2% of the change), exposure +93,059 (31.4%), and rising background COPD death rates +89,973 (30.4%). Country-level patterns diverged sharply from this global average: countries in which exposure was the leading driver of the increase accounted for 62.6% of the 2023 global burden, against 27.7% for population size and 8.2% for the background COPD rate. Had ozone exposure remained at 1990 levels, an estimated 326,192 deaths would have occurred in 2023, implying 142,526 deaths (30.4% of the 2023 burden) attributable to the change in exposure. South Asia accounted for 285,164 deaths in 2023, with exposure the single largest driver there (39.9%). In high-income countries and in Central and Eastern Europe the exposure component was negative, averting an estimated 7,054 and 3,865 deaths respectively.Conclusions. Rising ozone-attributable COPD mortality is not driven predominantly by demography. Exposure change accounts for 31.4% of the global increase and is the leading driver across the countries carrying 62.6% of the current burden. Precursor emission controls have measurably reduced burden where they have been applied. These results are based on all-age data and therefore cannot separate population growth from population ageing.