Toronto, Jan 9 (IANS): Just two hours of exposure to air pollution caused by diesel exhaust fumes can lead to fundamental health-related changes in biology by switching some genes on while switching others off, new research has found.

"This study shows how vulnerable our genetic machinery can be to air pollution, and that changes are taking place even if there are no obvious symptoms," the researchers noted.

Such exposure affected the chemical "coating" called methylation, that attaches to many parts of a person's DNA, the findings showed.

Methylation is one of several mechanisms for controlling gene expression.

"Any time you can show something happens that quickly, it means you can probably reverse it - either through a therapy, a change in environment, or even diet," said senior author Chris Carlsten, an associate professor at University of British Columbia in Canada.

For the study, the researchers exposed volunteers to diluted and aged exhaust fumes that are about equal to the air quality along a Beijing highway, or a busy port in British Columbia.

Diesel exhaust caused changes in methylation at about 2,800 different points on people's DNA, affecting about 400 genes.

In some places it led to more methylation; in more cases, it decreased methylation, the findings showed.

Methylation changes on several places in the genome that have a direct bearing on lung health, the researchers added.

One of those changes would lead to less production of a protein called GSTP1, which helps "clean up" toxic molecules that disrupt the normal functioning of cells.

The study appeared in the journal Particle and Fibre Toxicology.