Cancer-causing mineral found in US road gravel

Erionite, which is linked with mesothelioma, has found in the roadstone used in parts of the USA.  Weathering and mechanical erosion from tyres produces fine particles which can become airborne in dry weather and may be inhaled.

http://www.eurekalert.org/pub_releases/2011-07/uohc-nsf072511.php

Road dust is one of the contributors to urban air pollution.  It works its way into buildings, and into lungs.