Kraków: Residents of the old Polish capital, whose winter smog once ranked among the worst in Europe, have watched their skies slowly clear over the past decade. A continental stocktake from the European Environment Agency confirms the trend while delivering an uncomfortable caveat: cleaner is not yet clean.

The agency’s air quality assessment, drawing on measurements gathered across the Union, finds that standards for fine particulate matter and nitrogen dioxide are now met in most regions. That marks real progress after years of falling emissions from cars, power plants and home heating. Yet at up to a fifth of monitoring stations, pollution still exceeds current limits, with the stubborn offenders being coarse particulates, ground-level ozone and a carcinogen called benzo(a)pyrene that lingers where people still burn wood and coal.

Ozone is the awkward case. Unlike soot from a chimney, it is not pumped straight into the air but cooks up in sunlight from other pollutants, which means hotter summers can worsen it even as underlying emissions fall. The agency warns that meeting the tighter limits the Union has set for 2030 will demand action that reaches beyond the easy wins already banked.

The human toll keeps the numbers from feeling abstract. More than ninety per cent of city dwellers in the Union breathe air that exceeds the World Health Organization’s health guidelines, which are stricter than the Union’s own legal limits. Earlier analysis built on the agency’s data put the economic cost of that pollution at around 600 billion euros a year, close to four per cent of the bloc’s output, once illness, lost work and premature death are counted.

The damage does not stop at human lungs. Nitrogen and ozone settle onto forests, grasslands and lakes, tipping the chemistry of ecosystems and eroding the biodiversity the Union has pledged to protect. Officials want to shrink the area where air pollution threatens sensitive habitats by a quarter before the decade ends, a target that trails behind schedule.

National governments hold most of the levers. Low-emission zones, cleaner heating subsidies and tighter industrial permits all sit with capitals and city halls, and the pace of change varies wildly between places that have embraced them and those that have not. The agency’s role is to hold up the mirror, and its latest air quality report shows a continent that has cleaned much of its air without yet making it safe.

For Kraków, the lesson is bittersweet. The worst days are fewer, but the work of erasing the last and most stubborn pollution has barely begun.