GLOBE-Net, August 2, 2012 - Measures to control
methane and black carbon (soot) emissions could improve air quality
and public health, in addition to slowing the rate of climate
change, according to recent research. By 2030, the reduced
pollution could prevent between 700,000 and 4.7 million premature
deaths each year, with 80% of the benefits occurring in Asia.
Previous studies have linked the formation of ozone at ground
level (tropospheric ozone) and black carbon (soot) pollution with
health problems, in addition to playing a role in climate change by
causing the atmosphere to warm.
Methane is an ozone precursor, i.e. methane contributes to the
formation of tropospheric ozone. Methane is also a potent
greenhouse gas. Manmade emissions of methane come from a variety of
sources including the production and distribution of fossil fuels,
livestock, landfills, wastewater treatment and rice
Black carbon is a component of soot and particulate matter
PM2.5, fine particles less than 2.5 micrometres (µm) in diameter.
Black carbon is commonly produced from natural (e.g. natural forest
fires) and human sources, including diesel vehicles, traditional
cooking stoves, and industrial plants.
People exposed to surface ozone
can develop respiratory diseases, whilst exposure to PM2.5 can lead
to heart and lung (cardiopulmonary) diseases, including lung
cancer.For this study, the researchers
assessed the impact on air quality and public health of control
measures that reduce methane and black carbon pollution in five
The 14 selected emission control measures were selected based on
their expected effectiveness to mitigate short-term climate
Examples of methods to cut methane emissions include
reducing methane leakage from long-distance gas pipelines and
controlling methane emissions
from livestock. Technical measures to reduce emissions of black
carbon include fitting diesel particle filters on vehicles and
improving cooking stoves in developing countries.
The study found that full implementation of all the emission
control measures by 2030 would reduce PM2.5 concentrations by
23-34% and ozone concentrations by 7-17%. In addition, between
0.6-4.4 million black carbonrelated premature deaths and between
0.04-0.52 million ozone-related premature deaths could be avoided
globally each year.
Over 80% of the health benefits would occur in Asia, as large
numbers of people are exposed to high concentrations of pollution
in this region. There would also be significant health benefits for
Africa, although not to the same extent as in Asia.
Out of all the emission control measures, those that reduce black
carbon would achieve 98% of all avoided premature deaths. Black
carbon control measures also reduce other non-methane ozone
precursors, in addition to other particulate pollution, especially
organic carbon particles. There is also a stronger relationship
between exposure to PM2.5 and loss of life expectancy than between
exposure to ozone and premature death.
Burning solid fuel indoors (for cooking) has been estimated to
cause 1.6 million premature deaths each year. In this study the
effect of indoor exposure to smoke from cooking was not included in
the results, suggesting the beneficial impact on health of reducing
black carbon has been underestimated.
This study demonstrates that measures designed to control methane
and black carbon emissions for their potential benefits on global
short-term climate, would deliver substantial air quality
co-benefits that could help avoid many premature deaths by
Source: Anenberg, S.C., Schwartz, J., Shindell, D. et al.
(2012) Global Air Quality and Health Co-benefits of Mitigating
Near-Term Climate Change through Methane and Black Carbon Emission
Controls. Environmental Health Perspectives. 12 : 831-839.