Black Carbon

A scientific citizenship project

The “Black Carbon Project” is born from the desire to raise community awareness about environmental issues by using a participatory process for the direct measurement of this air pollutant.

Despite this substance being part of the PM10, it is currently not subject to any specific limits. However, black carbon has an influence on the average air temperature and therefore on global warming, and can also create respiratory problems.

MUSE has therefore launched a campaign to measure this pollutant leaving it to the people themselves to assess its concentration and share the results.

Anyone who wants to participate can discover what it means to be a citizen scientist, that is, a citizen who with the data they collect and share provides a contribution to research and simultaneously expands their knowledge on major global issues.


 
 
Definition of Black Carbon
and correlation with environment and health
There are a number of atmospheric pollutants by chemical composition, size and different concentrations. Depending on their chemical and physical characteristics may be more or less harmful to the human body and for the global climate. For this reason, some substances, such as ozone, nitrogen dioxide and sulfur dioxide, are monitored more than others. One of these pollutants that is taking on increasing importance and which, in a few years, the law should establish the limits for release into the atmosphere, is the so-called Black Carbon.  

The Black Carbon particulate, a dark brownish color composed primarily of carbon, is the product of the incomplete combustion of fossil fuels or biomass, such as wood, agricultural waste or manure. For example, it is emitted by diesel engines and the old home stove prevalent in underdeveloped countries (Nepal, India, etc.).

The Black Carbon belongs to the family of climate-controlled compounds short-lived — the so-called SLCF (short-lived Climate brute Forcers) remains in the atmosphere for a few days, not decades as for carbon dioxide. Although it remains in the atmosphere for a short time and is present at a concentration of 2 or 6 orders of magnitude lower than carbon dioxide, Black Carbon is a significant contribution to global warming, especially in Arctic regions reached from Black Carbon particles.

In these regions the effects of soot are amplified: its dark colour, in fact, makes a strong absorber of solar radiation; as a result, once deposited on snowy or icy surfaces, it decreases their albedo effect by increasing the temperature and thus dissolving more rapidly the ice or snow.

Some researchers are also studying the function of the brown clouds, formed by the interaction of particles of Black Carbon with other present in the atmosphere, Earth's radiative budget.

From the point of view, the particulate matter of Black Carbon belongs to the family of PM10, or more precisely to the PM 2.5, since it has a diameter of less than 2.5µm. This characteristic makes it very harmful to the human body, because its magnitude is such as to be able to penetrate deep into the lungs. Therefore prolonged exposure to Black Carbon-rich gases can result in respiratory diseases.
 
Credits
Muse, Trento, Italy
David Tombolato, Matteo Cattadori, Alice Pontalti and Irene Carroll

Nexleaf Analytics, Los Angeles, California, USA
Eric Graham and Nithya Ramanathan

APPA (Provincial environmental protection), Trento, Italy

Faculty of Engineering-Environmental and Mechanical Engineering (UniTn), Trento, Italy
Dino Zardi
 
Measurement of Black Carbon
There are various ways to measure black carbon. The one we use involves the use of an air sampler, i.e. a pump connected by a tube to a quartz fibre filter. When the sampler is in operation, the air passes through the filter leaving behind some of the particles from which it is formed. The instrument is left on for several hours, after which the filter is removed and placed on a graphical measure with a QR code, which allows the computer to automatically find the location of the filter on the surface of measure, and by a series of colours it is possible to determine the amount of black carbon. A photo is then taken that is sent, along with some data (duration of sampling, flow, size of the area exposed to the air filter during sampling) to a server in California and that server automatically analyses the image of the filter, applying an algorithm specially created by researchers at the Nexleaf Analytics (Los Angeles, California, USA), who returns the values of the concentration of black carbon on the surface of the filter and the volume of air taken in by the sampler.  


Go to map of measurements in Trentino
 
Limit thresholds for health
As of yet, there are no precise values on the concentration limit below which black carbon is considered harmless. However, the WHO provides guidelines on air quality by placing the average annual PM2.5 to a level of 10 μm/m3.

As for black carbon, we can only say that the highest values, recorded to date in the world, are the order of tens of micrograms (mM) per cubic meter. For example, in “Project Surya”, which studied air pollution in some rural areas of the Indo-Gangetic plain, there was a peak daytime concentration of black carbon equal to some 60 µm/m3.