Technical Notes: Emissions of Common Anthropogenic Pollutants

VARIABLE DEFINITIONS AND METHODOLOGY:
Sulfur dioxide, or SO2, is a primary contributor to acid rain.  High concentrations of sulfur dioxide affect 
breathing and may aggravate existing respiratory and cardiovascular disease. Sulfur dioxide forms when 
fuel containing sulfur, such as coal and oil, is burned, when gasoline is extracted from oil, or when metals 
are extracted from ore.  Petroleum refineries, cement manufacturing facilities, metal processing facilities, 
locomotives, large ships, and some off-road diesel equipment burn high-sulfur fuel and release large 
quantities of SO2 into the air.

Nitrogen oxides, or NOx, is the generic term for a group of highly reactive, acidifying gases, all of which 
contain nitrogen and oxygen in varying amounts. Nitrogen oxides are a precursor to ground-level ozone, 
which can trigger serious respiratory problems.  NOx also contributes to acid rain and global warming.  It 
forms when fuel is burned at high temperatures, as in a combustion process. The primary sources of NOx 
are motor vehicles, electric utilities, and other industrial, commercial, and residential fuel-burning sources.

Carbon monoxide, or CO, is a precursor gas of ground-level ozone, which can trigger serious respiratory 
problems.  When CO enters the bloodstream, it reduces the delivery of oxygen to the body's organs and 
tissues.  Exposure to elevated CO levels can cause impairment of visual perception, manual dexterity, 
learning ability and the performance of complex tasks.  CO is formed when carbon in fuel is not burned 
completely and is a component of motor vehicle exhaust.  Other sources of CO emissions include 
industrial processes (such as metals processing and chemical manufacturing), residential wood burning, 
and natural sources such as forest fires.

Non-methane VOCs (Volatile Organic Compounds) are chemicals that vaporize at room temperature, 
including benzene, toluene, methylene chloride and methyl chloroform.  Common sources that emit VOCs 
include housekeeping and maintenance products, cars, and building and furnishing materials, such as 
solvents, paints, and glues.  In sufficient quantities, VOCs can have adverse health effects on humans; 
some are suspected or known carcinogens.  VOCs are also precursors to ground-level ozone, which can 
trigger serious respiratory problems.

The Dutch National Institute of Public Health and the Environment (RIVM) and the Netherlands 
Organization for Applied Scientific Research (TNO) gather disparate data on greenhouse gases and 
atmospheric pollutants and compile them into complete sets of emissions data for the Emission Database 
for Global Atmospheric Research (EDGAR). 
 
To ensure a consistent approach across countries, RIVM obtains activity data from a range of 
international statistic data sources (IEA, UN, FAO, OLADE, etc.), and selects emission factors from 
international publications (Intergovernmental Panel on Climate Change (IPCC) Guidelines, US-EPA 
reports, etc.).  For example, production data for industrial processes are based on UN Industrial 
Commodity Statistics, supplemented with data from the USGS, SRI, and IISI. For some nations, 
interpolations and extrapolations are necessary to arrive at complete time series, with special attention 
given to new Economies in Transition countries to match the older totals for the former countries. 
Emission factors for CO2, CH4, and N20 are described in Sectoral Emissions Inventories published in 
Environmental Science & Policy, while those for nitric acid production are based on Intergovernmental 
Panel on Climate Change (IPCC) Guidelines. 
 
For further information on variables and collection methodologies, refer to the documentation provided by 
the EDGAR site at: http://arch.rivm.nl/env/int/coredata/edgar/edgar32-datasources-methods.doc. 
Information on the IPCC methodologies utilized by RIVM and TNO is available at http://www.ipcc-
nggip.iges.or.jp/public/gl/invs1.htm.  

FREQUENCY OF UPDATE BY DATA PROVIDERS: 
The Emission Database for Global Atmospheric Research (EDGAR) updates emissions data depending 
on the availability of international statistics.  Currently, data are available for 1990 and 1995.



DATA RELIABILITY AND CAUTIONARY NOTES: 
RIVM and TNO use the same methodologies for calculating emissions as the IPCC.  In addition, global 
totals comply with budgets used in atmospheric studies, and the data were based on international 
information sources. However, data for some countries are uncertain, especially in the categories of 
methane and nitrous oxide emissions.  The uncertainty is caused by the limited accuracy of both 
international activity data and national emission factors.  

SOURCES:  
Dutch National Institute for Public Health (RIVM) and Netherlands Organization for Applied Scientific 
Research (TNO).  2001.  The Emission Database for Global Atmospheric Research (EDGAR) 3.2.  
Precursors: NMVOC (Non-Methane Volatile Organic Compounds): Aggregated Emissions 1990/1995.  
The Netherlands: RIVM.  Electronic database available online at: 
http://arch.rivm.nl/env/int/coredata/edgar/.