The World Health Organization (WHO) fact sheet on ambient (outdoor) air quality and health highlights the significant health risks posed by outdoor air pollution. It reports that in 2019, ambient air pollution was responsible for approximately 4.2 million premature deaths globally, primarily due to exposure to fine particulate matter (PM2.5), which leads to cardiovascular and respiratory diseases, as well as cancers. The fact sheet emphasizes that 99% of the global population lived in areas exceeding WHO air quality guidelines in 2019, with low- and middle-income countries bearing the highest burden. To mitigate these health impacts, WHO advocates for policies and investments that promote cleaner transportation, energy-efficient housing, improved waste management, and access to clean household energy.