B vitamins protect heart and blood vessels against air pollution
If exhaust fumes and heavy industry emissions increase the concentration of particulate matter in the air to such an extent that cardiovascular damage occurs, a supplement containing B vitamins may significantly reduce the harmful impact of air pollution. This is evident from a small experimental study, which researchers at Columbia University published in 2017 in Scientific Reports.Study
On 2 different occasions, the researchers got 10 healthy subjects to breathe concentrated polluted air for 2 hours. The air contained 250 micrograms of particulate matter per cubic centimeter: small and toxic soot particles in exhaust gases, which slip into the blood vessels through the lungs. When there is a lot of particulate matter in the air, the number of people who have a stroke or heart attack increases.

On one occasion, subjects took placebo every day for 4 weeks prior to exposure. The other time they took a supplement with a solid dose of folic acid, vitamin B12 and vitamin B6.
Shortly after exposure to the polluted air, the subjects' heart rate increased. This did not happen if the same subjects had taken B vitamins for 4 weeks.

Click on the figures below for a larger version.

After exposure to the contaminated air, the concentration of white blood cells [WBC] in the blood also increased. Those white blood cells probably became active because air pollution causes inflammation in the body. Inflammatory processes can damage blood vessels, and probably damage tissues in other ways as well.
Again, supplementation with B vitamins protected against this effect. If the subjects had taken B vitamins in the weeks before exposure, the white blood cell concentration remained stable.

"Apart from avoiding exercising outdoors at peak pollution times, sensitive individuals have limited options to reduce exposure and associated cardiovascular risk", write the researchers."While regulation is the backbone of prevention, residual risk remains for those who are sensitive, and high exposures are, unfortunately, the rule still in many megacities throughout the world."
"Our project inaugurates a line of research for the development of preventive pharmacological interventions using B vitamins to contain the health effects of air pollution. Future studies will identify the precise pathophysiological processes of PM-induced cardiovascular responses and inflammation, as well as the mechanistic pathway underlying the protective effect of B vitamins."
Sci Rep. 2017 Apr 3;7:45322.