How Does Black Carbon Affect Human Health?

In recent years, black carbon has come to be recognised as a chief contributor towards climate change and global warming, with some experts speculating that it could be the second biggest driver behind carbon dioxide. As a particle pollutant rather than a gaseous one, it is far more effective at trapping heat in the atmosphere, even if it does persist for significantly less time than CO2.

However, concentrating solely on the environmental impact of black carbon neglects its ramifications for human health. As a constituent part of particulate matter (PM), black carbon has the ability to penetrate the lungs and even the bloodstream of those exposed to it, thus potentially causing long-term respiratory and cardiovascular complications and even premature death.

Black carbon as particulate matter

PM has been widely recognised as one of the most damaging forms of pollution today, especially in urban environments. With some particles under 2.5 microns in diameter (known as PM2.5, with a diameter 30 times finer than a human hair), these microscopic pieces of pollution can be easily inhaled into the lungs and even absorbed into the bloodstream.

Although their full effects are not yet known, they have been suspected of contributing to the contraction of cancer, heart disease and other terminal illnesses. Indeed, the UN speculates that exposure to outdoor air pollution is responsible for 4.5 million deaths each year, while indoor contamination claimed the lives of as many as 3.2 million people annually.

Given that black carbon is one of the principal ingredients in PM (alongside ammonia, mineral dust, nitrates, sulphate, sodium chloride and water), it’s only logical to assume that exposure to black carbon is every bit as dangerous. Indeed, the UN still recommends using PM2.5 as the primary barometer of human exposure, but that black carbon concentrations can provide an enlightening secondary source of information.

Those in developing world most at risk

In historical terms, most black carbon emissions have been caused by the incomplete combustion of fossil fuels at coal-burning power stations, diesel combustion engines and the biomass burning stoves in the western world. However, heightened awareness over the health dangers of these practices has led to tighter regulations for such practices in places like the USA and Europe, resulting in reduced levels in recent years.

By contrast, the combustion of wood or other biomass sources still constitutes the primary means of heating households and cooking food in much of the developing world. This is especially true in certain parts of Africa, Asia and Latin America, which contribute almost 90% of the world’s black carbon emissions today. Since this combustion often takes place in confined spaces, the individuals (most often women and children) exposed to it are most at risk.

Elsewhere, the widespread practice of crop stubble burning and land clearing in these parts of the world also endangers the health of the farmers and workmen tasked with carrying it out. In order to curb these damaging health impacts, it’s imperative that stricter legislation is put in place on a global scale to bring black carbon levels down and reduce the strain on public healthcare.