The American Lung Association's State of the Air report , released on April 24, highlights that more than 40% of US citizens—more than 141 million people—live in areas with unhealthy levels of ozone and particulate matter. Deteriorating air quality marks an alarming trend for a country that has reduced emissions of common pollutants since the 1980s. Wildfires and heatwaves in parts of the country most affected by climate change have driven record-breaking levels of pollutants in some of the most densely populated cities.

PM2·5 exposure is a leading risk factor for death worldwide. Chronic obstructive pulmonary disease (COPD), once considered mainly a consequence of tobacco smoking, is still a burden worldwide despite tobacco control measures, and ambient particulate matter is now considered a major risk factor for COPD. In the USA, air pollution ranked as the 11th most prominent risk factor of death and disability in 2017; COPD was also the fifth most common cause of death and premature mortality, and the third most common cause of death and disability. These data show that COPD is a larger health burden in the USA than in many other industrialised countries, which should amplify concerns about the report's findings since air pollution disproportionately harms adults with compromised lung function.

Another threat is the effect on children and adolescents whose lungs are still developing. At least half of COPD burden in adulthood is believed to be caused by poor lung growth rather than accelerated decline in lung function. Existing COPD treatment strategies focus on slowing the decline in lung function, but a different treatment strategy might become necessary if lung function is impaired by early adulthood. In this week's issue of The Lancet, Mark Dransfield and colleagues announce the new Lancet Commission to develop transformational recommendations for COPD prevention, detection, and treatment.

High air pollution concentrations could be priming an epidemic of chronic respiratory disease. The USA must show leadership in bolstering stringent policies that minimise these adverse health consequences of climate change, facing up to the changing disease burden and risk factor pattern for cardiorespiratory diseases.

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Article Info Publication History Identification DOI: https://doi.org/10.1016/S0140-6736(19)30992-4 Copyright © 2019 Elsevier Ltd. All rights reserved. ScienceDirect Access this article on ScienceDirect