A novel test method was used to study the concentration and size distribution of airborne wear particles from disc brake materials. A pin-on-disc tribometer equipped with particle counting instruments was used as test equipment. Four different nonasbestoses-organic (NAO) linings for the U.S. market and four different low metallic linings for the EU market were tested against material from gray cast iron rotors. The result indicates that the low metallic linings are more aggressive to the rotor material then the NAO linings, resulting in higher amount of wear and concentrations of airborne wear particles. But, although there are variations in the measured particle concentrations, similar size distributions were obtained regardless of lining material.