Published on Monday, the research suggests that vitamin B supplement could potentially reduce the impact of the tiny particles on the human body, although they stressed that research was in its early stages and the sample size was small.

Particulate matter, or PM, is a type of air pollutant consisting of small particles of different sizes — from tiny molecular clusters to dust or pollen that we can see. PM2.5 has a diameter of fewer than 2.5 micrometers, about 30 times smaller than a human hair.

“These particles are so small they can go into our respiratory system. They can go deep into our lungs “ Chak K. Chan, professor of Atmospheric Environment at the School of Energy and Environment, at Hong Kong’s City University told CNN.

Once the particles are inhaled they can result in lung and systemic inflammation and stress, experts say. And scientists suspect exposure to PM2.5 can cause “epigenetic” changes to our cells — disturbances or mutations that can damage our health.

The study also involved researchers at Harvard’s TH Chan School of Public Health.

For this study published in the science journal PNAS, 10 volunteers were initially exposed to clean air and given a placebo to check their baseline responses.

The group then took another placebo for four weeks before being exposed to heavily polluted air from downtown Toronto, where an estimated 1,000 cars pass every hour. The bad air was delivered to the volunteers through an “oxygen type” face mask.

The experiment was then repeated, with each volunteer taking a B vitamin supplement daily — made up of 2.5 mg of folic acid, 50 mg of vitamin B6, and 1 mg of vitamin B12.

B6 can be found in liver, chicken and nuts, among other things, and B12 in fish, meat, eggs, milk and some cereals. The researchers found that four weeks of B vitamin supplements reduced the damage of PM2.5 exposure by 28-76%.

The results highlight how prevention at an individual level could be used to fight the adverse effects of PM2.5, the researchers said.