On September 22^nd, the World Health Organization updated its Global Air Quality Guidelines, cutting its recommended limits for air pollution. Suggested levels for key pollutants – like particulate matter, nitrogen dioxide, and carbon monoxide – were considerably reduced.

The change comes as accumulating evidence points to air pollution’s adverse health effects, even at levels previously thought safe. Linked to an array of health problems, including heart and lung diseases, strokes, and cancer, the W.H.O. estimates that air pollution is responsible for seven million premature deaths annually, placing its human costs on par with smoking. This “makes air pollution the single most important environmental risk factor for our health,” explained W.H.O. Regional Director for Europe, Dr. Hans Kluge.

Given current air pollution levels, such concerns seem well placed. Even before the new guidelines, an estimated 90% of the global population was exposed to concentrations of pollution above the recommended limits. As the updated guidelines lower those limits, the crisis’s scale now seems far worse than previously thought. According to environmental law charity ClientEarth, E.U. and U.K. legal limits for the most harmful pollutants are now more than four times higher than the W.H.O.’s recommended maximum levels.

The W.H.O. presented those new guidelines as a major step towards addressing air pollution, aimed at mitigating health and climate costs. But although scientists applauded the new recommendations, many expressed concerns over their implementation. Roy Harrison, professor of environmental health at the University of Birmingham, insisted that “the new guidelines will not be achievable for decades, if at all.” The W.H.O. report might provide a model for air quality, but the sticking point remains implementation.

As Jonathan Grigg, professor of environmental medicine at the University of Queen Mary London, explained, “[P]oorer populations and more socially disadvantaged populations are going to be more exposed.” Because air pollution largely stems from urbanization and economic development dependent on fossil fuels, developing nations often have higher levels of air pollution, endure the greatest health costs, and face the greatest challenges in addressing the issue. In India, for instance, air pollution cuts lives short by an average of six years – compared with two years globally. The country’s average pollution levels would need to be reduced eleven times over to meet the new recommendations.

Combatting air pollution, therefore, will require concerted political effort. The new recommendations’ announcement comes in the weeks before Cop26 in Glasgow, where U.N. member-states are expected to make new commitments to limiting climate change. That context was keenly emphasized throughout the launch of the Air Quality Guidelines, with the W.H.O. explaining that reducing emissions would improve air quality while simultaneously mitigating global warming. “The guidelines,” Dr Kluge asserted, “provide a robust health argument that goes hand in hand with the global fight against climate change and environmental pollution.” W.H.O. Director General, Dr. Tedros Adhanom Ghebreyesus, urged “all countries to put the guidelines to use, to save lives, support healthy communities and help address the climate crisis,” pressing for national commitments ahead of Cop26.

Whether W.H.O. aspirations for Cop26 will be fulfilled remains to be seen. The crisis’s scale requires substantive action, but a recent report from the Guardian of pessimism amongst key players gives little cause for confidence. Success can only come through close and equitable cooperation, the possibility of which seems increasingly jeopardized by escalating international tensions – particularly between the largest polluters, the U.S. and China. However, the implications of the W.H.O. report are clear. The cost of such conflict – the cost of failing to cooperate – is not only our climate, but our health.