Forest fires and car exhaust is present in tobacco smoke also.

Cigarette smoke prevents stem cells from growing to be cartilage A toxic pollutant pass on by oil spills, forest fires and car exhaust is present in tobacco smoke also, and may represent another way in which cigarette smoking delays bone recovery, according to analyze presented at the annual conference of the Orthopaedic Study Society in SAN FRANCISCO BAY AREA http://cialissverige.org/lakemedel-online.html . In 2005, researchers from the University of Rochester Medical Center identified one ingredient in smoke cigarettes, nicotine, that delays bone growth by influencing gene expression in the two-step bone healing process: stem cells become cartilage; cartilage matures into bone.