Human exposure to suspended particulate matter in the ambient air is associated with premature death, disability, and chronic disease. Black carbon in the atmosphere absorbs sunlight and re-emits the energy as heat. When deposited on ice or snow, it reduces the surface reflectivity, causing the surface to absorb more sunlight. Black carbon is a short-lived pollutant (remaining in the atmosphere for only a few weeks), thus the strategies to reduce black carbon emissions could have a very rapid and significant effect on the rate of warming.
According to IPCC, black carbon is the third largest contributor to the positive radiative force that causes climate change. One kilogram of black carbon is approximately 460 times more potent than the equivalent quantity of carbon dioxide over a 100 year time span.
In January 2014, the Mexico City government started a real-time monitoring program to determine black carbon concentrations in ambient air of selected sites within the city. At present, the project provides real-time information about black carbon concentrations in ambient air in five selected sites in Mexico City. This information complements real-time data gathered by the ambient air monitoring system, namely: criteria pollutants, air toxics, surface and lower atmosphere meteorology, including solar radiation.
The project is primarily oriented to assess the real-time concentrations of black carbon in ambient air as a base for public policies to reduce black carbon emissions and the protection of public health. In addition, gathered data will be used to run dispersion and photochemical models, conduct emissions inventories, visibility impact assessments and the identification of the emission sources to design policy actions for their control.
After at least one year of data gathering, the establishment of reduction targets and the design of reduction strategies will be assessed. It will then be possible to determine a basic strategy for the mitigation of emissions. After yet another year, it will be possible to monitor progress and adjust or establish new reduction targets.
While the project is primarily oriented towards improving public health, co-benefits include reduction of other suspended particulate matter species, CO2, NOx, and ozone precursors, as well as improved visibility and air quality.