I have noticed that the additional grade has been introduced to European AQI scale. At the same time the description (the legend) remains the sam - 5 grade scale (excluding no data category). I would be obliged for the info - where I can find detailed explanation of the said change (may be any documents, white papers, rules or official acts are available ?). In particular I have observed that the highest grade is connected only with PM10 parameter and in practice was used in singular cases (namely for some Spain locations). Rgds<br />Stanislaw
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