• Dutch National Institute for Public Health and the Environment (RIVM);
• Department of Air Quality, Energy research Centre of the Netherlands (ECN);
• Municipal Public Health Services (Amsterdam, Brabant - Zeeland).

Aim of this study is to evaluate the effects of traffic policy measures in busy streets on:

1. Air quality
2. Toxicological capacity of fine particulate matter
3. Respiratory health of residents.

Repeated measurements of air quality and health will be performed with a period of two years in between. In parallel, we will investigate trends at busy streets, city background and regional background locations to differentiate between different traffic policy measures/air pollution levels.

We aimed at 1125 volunteers living in 9 busy streets in the following cities: Amsterdam, Den Bosch, Den Haag, Tilburg and Utrecht. For comparison purposes, 625 volunteers were sought living in 4 regional background locations in the 'neighborhood' of those cities namely: Bussum, Oisterwijk, Voorschoten and Bilthoven.

At those 13 locations air pollution will be measured including PM10, PM2.5, NO and NO2 as well as the toxicity of PM particles (elements, metals, oxidative stress potential).

At the same locations, respiratory health of the residents will be measured with three tests: lungfunction, airway resistance and exhaled NO (a marker for inflammation in the lungs) tests will be performed. Also we asked the volunteers to fill in a questionnaire at the same time.

In this study we are particular interested whether an improvement in air quality results in an improvement in respiratory health of the people living close to busy streets. Other health endpoints related to air pollution are of course are of interest as well, for example cardiovascular diseases, but can not be investigated in this set up.

The traffic policy measures contains 'local' traffic policy measures to resolve air quality problems in busy streets as well as more 'general' policy measures like the environmental zoning system, implemented in the city centers. We will not be able to attribute (assumed) improvements in air quality to certain traffic policies, simply because various policies are and will be implemented at the same time.

The first round of air pollution and health measurements was performed from June 2008 to February 2009. Next (and last) round is scheduled two years later (June 2010- February 2011).