Story highlights Nitrogen dioxide pollution, much of it caused by diesel engines, poses a risk to health

Five EU nations could face court action if they don't respond to a warning over nitrogen dioxide levels

(CNN) The European Commission has issued "final warnings" to Germany, France, Spain, Italy and Britain for failing to address repeated breaches of air pollution limits for nitrogen dioxide, it said Wednesday.

Nitrogen dioxide pollution, much of it caused by road traffic, represents a serious health risk.

In a statement, the Commission said EU rules set clear pollution limits and obliged member countries to protect citizens from harmful air pollutants.

If Germany, France, Spain, Italy and Britain fail to respond satisfactorily to the warning within two months, the Commission could take the matter to the Court of Justice of the European Union.

"While it is up to the Member State authorities to choose the appropriate measures to address exceeding NO2 limits, much more effort is necessary at local, regional and national levels to meet the obligations of EU rules and safeguard public health," the Commission said.

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