Although the overall toxicity of bulk atmospheric particles is well known, researchers and air quality managers still face difficulties in the understanding of the most harmful species and sources, which is based on the knowledge of their individual impact on PMx levels. This chapter aims at reviewing the current knowledge of the impact on air quality of vehicle non-exhaust sources (as a whole and individually for road dust, brake wear, tire wear, and road wear). Ninety-nine peer-reviewed articles were found providing contributions ranges, often in comparison with vehicle exhaust contributions. The variability of contributions was explored relatively to particulate matter size fraction, type of location, and climate.