Breathing black carbon worse than smoking a pack of cigarettes a day

A study has found regularly breathing black carbon increases the amount of small blood vessels in the lungs, which researchers say is as bad for health as smoking a pack of cigarettes every day for 15 years.

The study, which was published in European Respiratory Journal, analysed monitoring data of 3,000 people from six US cities, calculating participants’ long-term exposure to black carbon and fine particulate matter (PM2.5) from transport and industry.

Between 2010-2012, participants’ pulmonary blood vessels were then measured using chest CT scans between, factoring in age, height, weight, sex, race and ethnicity, pack-years of cigarette smoking, exposure to secondhand smoke, medical history and other socioeconomic factors.

The researchers estimated that on average, study participants were exposed to annual levels of black carbon of 0.8 micrograms per cubic meter and fine particulate matter (PM2.5), another measure of air pollution that includes black carbon particles, of 11 micrograms per cubic meter.

Despite this relatively low average exposure, the study revealed exposures to a higher level of black carbon was associated with a greater volume of blood vessels in the periphery of the lungs, which is what happens to heavy smokers, often leading to lung disease.

Lead researcher Dr Carrie Pistenmaa Aaron of Columbia University explained: ‘A few previous studies have suggested a link between air pollution and the pulmonary circulation, but we wanted to evaluate whether there were associations between chronic air pollution exposure and the vascular structure of the lungs.

‘We were interested in the lung vasculature as we think it may be related to chronic lung conditions.’

Researchers believe that their findings add weight to the theory that exposure to diesel pollutants at what are considered relatively low levels may contribute to subtle changes in the lungs that may make people more prone to developing chronic lung disease.

‘No previous research has looked specifically at whether these changes in humans lead to disease, so we cannot say for certain how this may be affecting health,’ added Dr Aaron.

‘However, other studies of similar pulmonary vascular measures on CT and MRI in humans, in addition to a number of studies in animals, suggest that differences in the pulmonary vasculature might make people more likely to develop chronic lung disease.’

Dr Aaron says she plans to conduct further research that will look in more detail at how pulmonary blood vessels relate to chronic lung disease.