Key points from article :
Study tested the effect of dust and fuel particles on human scalp cells.
Common pollutants reduced the levels of four proteins responsible for hair growth and retention.
Effect was proportional to the amount of airborne particles.
Research was undertaken in a laboratory.
Further research needed to determine how this affects people in their day-to-day lives.
Proteins affected were beta-catenin, cyclin D1, cyclin E and CDK2.
