The CORINAIR Atmospheric Emissions Inventory Guidebook (CORINAIR 1999) gives a range of NH₃ emissions factors from industrial combustion of coal (0.01-0.86 g/GJ). An emission factor at the lower end of this range was assumed for the power stations in the UK. There are large uncertainties associated with this factor, and it was assumed to be constant across the time series. Coal consumption was taken from DUKES.

Where incinerators include energy recovery (i.e. are "waste to energy plant"), the CORINAIR reporting structure requires that they are classified under the power station sector.

The emission factor for NH₃ emissions from MSW combustion are derived from reported point source data. The calculated emission factor for each year is then applied to the total UK consumption of MSW in this sector. The mass of MSW used to generate electricity is taken directly from DUKES.

Emissions estimates for NH₃ are included from this sector in the NAEI inventory because emission factor and activity data are available. However, the emissions are not significant.

Lee and Dollard (1994) concluded that the most reliable emission factor was 1 kg NH₃ per tonne of coal. No data are currently available for the domestic combustion of coke, anthracite or wood and consequently the coal emission factor was used for these fuels. Detailed consumption data of different fuel types in the domestic sector are available indirectly from DUKES, and these were used for the time series.

The emission factor used in the NAEI estimates are taken from Martin et al (1997). This gives 4.13 mg NH₃ per cigarette. The number of cigarettes released for consumption is available from the H M Customs and Excise Annual Report (1999). This gives the number of cigarettes, cigars and hand rolled tobacco released each year. The hand rolled tobacco was converted into cigarettes and the data summed to obtain a total cigarette consumption for each year. However, consultation with ASH (pers. comm.) indicated that up to an additional 30% may be being consumed in the UK illegally- this was not taken into account as it was not possible to confirm.

Emissions estimates for NH₃ are included from this sector in the NAEI inventory because emission factor and activity data are available. However, the emissions are not significant.

The emission factor for power stations was used as there was no other suitable data. The consumption of coal in these sectors can be determined from the DUKES time series, and the resulting emissions are small.

This sector is a large consumer of coal for combustion. It has been possible to determine an emission factor by using point source emissions data reported to the Environment Agency’s Pollution Inventory (Pollution Inventory 1999). The resulting emission factors are therefore similar, but different for each year in the time series. The calculated emission factor for 1996 was 0.027 kt NH₃ per Mt of coal- considerably larger than the emission factor calculated from the power station data. The emissions from this sector give 0.31 ktonnes of NH₃. Coal consumed in this sector can be calculated from a range of data held by the NAEI.

Emissions from this sector arise from door leakage during coke production. Emission factors have been calculated by compiling the available data from the Pollution inventory (1999), from Scotland and Northern Ireland. In the vast majority of cases presented in this report, the presence of point sources in Scotland and Northern Ireland is also known from other data sources. Hence a total UK figure can be compiled. This has enabled a typical emission factor to be determined for individual years (although the same factor is applied across different years in this case). The amount of coke made is available from DUKES. The emissions from this source are approximately 0.1 ktonnes of NH₃.

The emission factor used for this sector has been taken from a USEPA publication (USEPA: AP42 Compilation of Air Pollutant Emission Factors). The amount of coal used in this production process can be determined indirectly from data available from DUKES. Th total emission is not large.

The emission reported in this sector comprises a sum of the Emissions reported in the Pollution Inventory, and individual plant from Scotland and Northern Ireland. All of the inorganic chemistry industry is included with the exception of fertiliser manufacture and sugar production from beet.

There are a number of production processes in the chemical industry which are listed in the Pollution Inventory, but which have not been individually included in the sectors above. These remaining smaller processes are aggregated into "Production processes: Chemical Industry" in the NAEI. The sources in this sector include: acid processes, petrochemical processes, processes involving halogens and a number of other minor source groups included as process emissions. It is intended that some sector reallocation is conducted for the next NAEI inventory.

The emission factor for this sector was taken from a personal communication with staff at British Sugar (the only sugar beet processors in the UK). British Sugar have been conducting extensive studies of their environmental emissions and note that the emissions per mass of beet vary across different seasons depending on the growing conditions. However, the quoted emission factor of 0.1 tonnes of NH₃ per ktonne of beet sliced is considered to be a reliable average value. Data on the mass of the annual sugar beet crop has been provided by British Sugar for the period of 1990 to 1999. The mass of beet that has been washed and topped/tailed has been used, i.e. the mass being sliced. This varies by year, but is generally a little less than 10 Mtonnes of beet.

Emissions from this sector represent the emissions from the mineral fibre industry. Emissions of NH₃ have been taken directly from the Pollution Inventory (1999).

The sources included in this sector are emissions from non-aerosol household products used for cleaning and hair applications and leakage of NH₃ refrigerant. The emissions given by the NAEI have been taken directly from Sutton et al (2000a) as these were considered to be the most reliable data that are currently available.

The data given here is taken from the NAEI Road Transport Emissions Model which gives the official UK estimates of pollutants for the UK.

The emissions factors for this sector have been determined from reported point source data. The mass of waste being incinerated can be determined from DUKES and accompanying information. This is conducted in the NAEI on a routine basis to enable the calculation of a number of pollutants.

Emissions from landfill have been highlighted as the most uncertain of the potentially significant sources. The calculations outlined by Sutton et al (2000a) are based on work done by Eggleston (1992) and Munday (1990) which assumes a constant ratio with CH₄ emissions from landfill.

Emission factors and population data has been taken from Sutton et al 2000b. The emissions from this sector are very small (0.037 ktonnes of NH₃).

This sector includes waste water treatment and the disposal of sewage sludge to land. Data provided from a number of waste water treatment plant have been compared with estimates from published literature. Disposal of sewage sludge to land has varied across the time series. The activity data applied to the different years has been determined from the observed trend in the mass of sewage sludge disposed of to land (which has been greatly affected by the ban of disposal to sea).

Emissions from agriculture have been taken directly from the NH₃ emission inventory compiled for MAFF by a number of institutes. This includes estimates from manure and excreta of a variety of farmed animals and emissions from agricultural soils.

The estimates are taken directly from Sutton et al (2000a) as they are currently considered to be the most reliable information available.

Estimates of the emissions of NH₃ from field burning were made by Lee and Atkins in 1994 and gave a UK total of 4 ktonnes of NH₃ prior to the banning of field burning. Sutton et al (2000a) has made a more recent estimate of 1.9 ktonnes of NH₃ from biomass burning. Both sources of data have been combined to generate a time series from 1990 to 1999 which is likely to represent the transition which occurred when agricultural burning was significantly reduced.

NH₃ emissions have been calculated by using the most recently available data from Sutton. These estimated emission factors are based on mass of faeces, nitrogen content and volatilisation.

Emission factors for these sectors were taken from Sutton (2000b). To ensure consistency with other pollutants reported in the NAEI, population data was taken from a different source, but the resulting difference in emissions is insignificant. The total emissions from these two sources sums to 1.2 ktonnes in 1996.

Maggot Farming and fish processing were investigated as potential sources of NH₃. Preliminary data suggests that both are only small sources of NH₃. A more detailed investigation will be conducted for the next emissions inventory.