Short answers, pulled from the story.
Air pollution kills 7 to 8 million people every year, a death toll that exceeds the combined fatalities from war and terrorism. In 2021, air pollution contributed to 8.1 million deaths, with outdoor particulate pollution accounting for 4.7 million of these fatalities.
The most deadly component is particulate matter, specifically fine particulate matter known as PM2.5, which are smaller than 2.5 micrometers. These microscopic solid or liquid particles can penetrate deep into the lungs and enter the bloodstream, causing stroke, heart disease, and lung cancer.
The Great Smog of London occurred in 1952 and caused approximately 12,000 deaths. This event led to the Clean Air Act of 1956 in Britain and marked a turning point in air pollution regulation.
Air pollution affects 99% of the global population according to World Health Organization data. This invisible threat is a present reality impacting both outdoor environments and the homes where billions of people cook and heat their living spaces using polluting fuels.
The World Bank estimates the economic cost of air pollution at over 8 trillion dollars annually, representing more than 6% of the global gross domestic product. The OECD predicts that direct market impacts on productivity and healthcare could reach 1% of global GDP by 2060.
The World Health Organization halved its recommended safe limit for particulate matter from 10 micrograms per cubic meter to 5 micrograms per cubic meter in 2021. This update reflects evidence that fine particles continue to cause harm even at levels below previous guidelines.