UN Framework Convention on Climate Change (UNFCCC) Secretariat (see: http://unfccc.int).
UNSD/UNEP Questionnaire 2004 on Environment Statistics, Air section, marked with " * ".
United Nations, Department of Economic and Social Affairs, Population Division, World Population Prospects: The 2008 Revision, New York, 2009 (advanced Excel tables).
- Emissions due to transport, other fuel combustion, and other sources.
- The high value is due to its national circumstance of heavy dependence on crude oil as main source of primary energy (80%).
- 1990 figure does not include NOx from energy sector, which constitutes large share of total emissions. The percentage change is calculated based on 1991 data.
- 1994 figure is considered as an uncharacteristically high in terms of GHG emissions. It was mainly influenced by large-scale extension of Niue's international airport runway, and the major construction and sealing of roads (230 km). The high per capita figure is also due to a very small population base.
- Burning of agriculture residue (cotton and soybeans) as source of NOx emissions increased significantly in 1994 from 1990 level. This could be consequence of change in the government policy in 1993 to move towards free-market economy that led to the rapid expansion of cash crops due to the rise in the international demand for these products.
- The high per capita figure is due to large emissions from fertilizer and burning and a small population base.
- The big increase in NOx emissions may be caused by a large increase of fire-cured tobacco. In the year 1990/91, a positive change of 112% was recorded for fire-cured tobacco. Tobacco growing in Tanzania impacts NOx emissions in following ways: (1) farming practice of "slash and burn" to prepare the growing area, and (2) curing of tobacco with biomass as fuel.
- The main source of NOx emissions was residential/commercial building sector and the primary source of heating in households are firewood, charcoal and coal. Combustion of these fuels are known to emit NOx.
Definitions & Technical notes:
Data on emissions of NOx are usually estimated according to international methodologies on the basis of national statistics on energy, industrial and agricultural production, waste management and land use, etc.
The most widely used methodologies are the 1996 Guidelines of the Intergovernmental Panel for Climate Change (IPCC) (see
http://www.ipcc-nggip.iges.or.jp/public/gl/invs1.html) which is the basis for reporting to the UNFCCC. The latest revision and update of this guideline is 2006 IPCC Guidelines for National Greenhouse Gas Inventories (see http://www.ipcc-nggip.iges.or.jp/public/2006gl/index.htm). In earlier years the guidelines produced for the UNECE Convention on Long Range Transboundary Air Pollution were widely used in Europe, and are still used in some countries.
The main source for NOx is burning of fuels, particularly petroleum products. In some countries agriculture and burning of savannas is also an important contributor, but estimating these emissions is more difficult and often data are not available.
NOx emissions per capita is calculated by UNSD.
Although standardised methods for calculating NOx emissions have been available for many years, calculating emissions of NOx is more difficult than for SO2, as many more parameters need to be taken into account. Therefore the quality of data on NOx emissions is considered to be only fair.