Making air quality indices comparable – assessment of 10 years of air pollutant levels in western Europe

Abstract

To address the incomparability of the large number of existing air quality indices, we propose a new normalization method that is suited to directly compare air quality indices based on the common European World Health Organization (WHO) air quality guidelines for NO₂, O₃, and PM₁₀. Using this method, we compared three air quality indices based on the European guidelines, related them to another air quality index based on the relative risk concept, and used them to assess the air quality and its trends in northwest central Europe. The average air quality in the area of investigation is below the recommended European guidelines. The majority of index values exceeding this threshold are caused by PM₁₀, which is also, in most cases, responsible for the degrading trends in air quality. Eleven out of 29 stations tested showed significant trends, of which eight indicated trends towards better air quality.

Keywords:

• air quality index
• health impact
• normalization method
• relative risk
• western Europe

Acknowledgment

We gratefully acknowledge the financial support of the National Research Fund in Luxembourg for the PhD scholarship of Hanna Lokys (4965163). Parts of the work have been done in the framework of the “Small Particles – environmental behaviour and toxicity of nanomaterials and particulate matter” (SMALL) project.