Black carbon, particulate matter (PM) and dust are very similar terms, which can confuse important discussions. We define each and outline their impacts on public and environmental health.
Particulate matter (PM) is now widely seen as a critical air pollutant, black carbon is gaining attention in climate research, and many disciplines refer to harmful dusts. However, it can be difficult to differentiate between these substances, which often have overlapping sizes and sources. In this article we explain, defining all three and touching on the impacts they have on human health, the environment, and our climate.
Definitions
Black carbon
Black carbon refers to particles comprising carbon, as well as some oxygen and hydrogen, arranged into a disordered crystal-like structure. They generally range in size from less than 100 nanometres (nanoparticles) to 2.5 micrometres (fine particles), but can be larger (“coarser”).
Black carbon is produced when carbon-containing materials such as fossil fuels, biofuels, and biomass are burnt. Usually, black carbon particles have resisted combustion, combusted partially, or resolidified in the combustion gases.
Black carbon is distinguished from many other components of aerosols by the fact that it strongly absorbs light.
Particulate matter
In contrast to black carbon, which is a certain type of particle, particulate matter comprises a huge variety of different particles and droplets suspended in air. It includes various liquid and solid compounds, organic matter, and black carbon.
Because of this diversity, PM is grouped according to size, with PM2.5 used to refer to particulate matter smaller than 2.5 micrometres and PM10 for matter smaller than 10 micrometres. Particle size has implications for health risk, with smaller particles able to reach deeper into the lungs.
Particulate matter originates from many sources, both natural and anthropogenic. Natural sources include wind-blown soil and dust, sea spray, and ash from wildfires, while combustion of fuels (in vehicles, industry, and homes) and other common processes such as tyre and brake wear are the main man-made sources.
Dust
Like particulate matter, dust refers to a huge variety of different particles. However, they can be much bigger, ranging from 1 micrometre to 100, and often settle under their own weight. 40 micrometres is usually the size at which particles become visible to the naked eye, so we can often see dust. Like particulate matter, dust has natural and anthropogenic sources, but is often a significant problem in workplaces, such as in the construction, agriculture, and materials processing industries.
Impacts of black carbon, particulate matter and dustIn humans, exposure to black carbon, PM, and dust particles can cause respiratory, cardiovascular, and cerebrovascular diseases. These result from inflammation, changes in the microstructure and function of the lung, and alterations in heart rate, blood pressure and blood clot formation. The World Health Organisation (WHO) estimates that 7 million people die each year from exposure to fine particles in polluted air. Air pollution can also affect our mental health, both directly – through chemical stress – and indirectly, for example, by affecting how we feel about where we live and work.
Black carbon, PM, and dust also affect ecosystems. Plants capture large amounts of air pollution, which benefits us, but often negatively impacts them. For example, particulate matter can reduce the amount of light reaching the leaves for photosynthesis and block the tiny pores needed for gas exchange. Chemical constituents of particulate matter (such as acids and alkalis) may damage leaves and affect a plant’s physiological reactions. Soil pH may also be altered – which is a key property in enabling plants to absorb nutrients, and fungal and bacterial nutrient cycling might be impaired. Particulate pollution may also enter waterways where it can harm aquatic animals.
Black carbon – in particular – is known as a super pollutant because it not only poses risks to health, but also intensifies climate change, although this role wasn’t always recognised. In the latter half of the twentieth century, soot (containing black carbon) was seen as a thing of the past. However, in the 1980s, combustion-generated particles were identified in the Arctic, indicating their ability to travel far and wide. Here, they collect on the ice, reducing its reflectivity and absorbing radiation, leading to increased warming. In this way, it is probable that black carbon is responsible for large losses of sea ice.
Eventually, highly absorbing black carbon was entered into climate models, which suggest that, after carbon dioxide, it is the second most significant contributor to current global warming.
Black carbon, particulate matter, and dust monitoring solutions
To mitigate the effects of particulate pollution on people, ecosystems, and the climate, monitoring is essential. Cura Terrae have solutions whatever your application, whether you’re monitoring particulate emissions to air from industry, dust levels in the workplace, air pollution in public spaces, or conducting scientific research.
Get in touch with our expert team.
Read more about particulate pollution in our other blogs:
- We discussed impacts, regulations, and monitoring solutions for dust in foundry workplaces.
- We took a close look at how the pioneering bettair® node overcomes many common PM-monitoring challenges.
- We investigated gaps in our understanding of black carbon.
