EU governments are failing to comply with air quality limits that are already weaker than the World Health Organization's recommendations, the bloc's auditors said on Tuesday.
The findings by European Union's watchdog come as Brussels is taking half a dozen member states to court over their failure to enforce the bloc's air quality laws.
Respiratory illness caused by pollution result in some 400,000 premature deaths a year, costing governments heavily in health care expenses, the European Court of Auditors found.
"There are still considerable impacts on public health," said Janusz Wojciechowski, one of the report's authors.
As many as 23 out of the bloc 28-nations are failing to comply with the existing limits on harmful pollutants such as nitrogen oxide and particulate matter, according to EU data.
Responding to the report, the EU executive said it was stepping up action to reduce pollution and defended its policy record, pointing to improvements in some areas.
"The Commission is fully aware that there is still an urgent need to further improve air quality in Europe," a European Commission spokesman said.
The Commission said in May it would sue Britain, France, Germany, Hungary, Italy and Romania at the bloc's highest court for breaching rules on air pollutants.