The study shows how individual-level prevention may be used to reduce the adverse effects of PM2.5 particles, which have an aerodynamic diameter of less than 2.5μm. These findings could have a significant public health benefit in regions of the world with frequent PM2.5 peaks.
The WHO estimates that 92 per cent of the world’s population currently lives in places where air quality levels exceed the WHO limit of 10μg/m3. Ambient PM2.5 pollution is one of the most prominent air pollutants because they deposit in the respiratory tract resulting in both lung and systemic inflammation and stress. While there has been substantial lowering of ambient PM2.5 achieved through large-scale emissions control policies over the past few decades, exposure peaks with adverse health consequences are still frequently recorded.
“The molecular foundations of air pollution’s health effects are not fully understood, and the lack of individual-level preventative options represent a critical knowledge gap,” says Oskar Karlsson, researcher at Uppsala University and Karolinska Institutet. “Our study launches a line of research for developing preventive interventions to minimise the adverse effects of air pollution. Because of the central role of epigenetic modifications in mediating environmental effects, our findings could very possibly be extended to other toxicants and environmental diseases.”
The study was conducted together with researchers in China, Singapore, Mexico and Canada. The researchers administered one placebo or vitamin B supplement (2.5mg of folic acid, 50mg of vitamin B6, and 1mg of vitamin B12) daily to each adult recruited for the trial. The vitamin B supplements significantly increased the median plasma concentrations of folic acid, vitamin B6, and vitamin B12. Median plasma concentrations for those who took placebos for four weeks were relatively unchanged.
All exposure experiments were conducted at the same time of the day. Ambient particles were drawn from an inlet next to a heavily trafficked street in downtown Toronto with more than 1,000 vehicles passing through each hour. Particles were delivered via an “oxygen type” facemask. Blood samples were collected in order to study DNA methylation and effects on mitochondria.
“While emission control and regulation is the backbone of prevention, high exposures are, unfortunately, the rule still in many megacities throughout the world. As individuals, we have limited options to protect ourselves against air pollution. Future studies, especially in heavily polluted areas, are urgently needed to validate our findings and ultimately develop preventive interventions using B vitamins to contain the health effects of air pollution,” says Andrea Baccarelli, MD, PhD, professor and chair of Environmental Health Sciences at the Mailman School.
The results are published online in the journal PNAS.