Methodological issues 7321 Choice of method

Aerosol emissions are considered prompt because all the initial charge escapes within the first year or two after manufacture, typically six months after sale for most sub-applications. Therefore, to estimate emissions it is necessary to know the total amount of aerosol initially charged in product containers prior to sale. Emissions of each individual aerosol in year t can be calculated as follows:

Equation 7.6 Emission estimation method for aerosol uses

Where:

Emissionst = emissions in year t, tonnes

St = quantity of HFC and PFC contained in aerosol products sold in year t, tonnes

St-i = quantity of HFC and PFC contained in aerosol products sold in year t-1, tonnes

EF = emission factor (= fraction of chemical emitted during the first year), fraction

This equation should be applied to each chemical individually. Wherever possible, activity data should be collected directly from the manufacturers or distributors of aerosols, ideally at the sub-application level to facilitate a Tier 2a approach. Globally or regionally derived activity data can be used to provide sub-application analysis where country-specific data does not exist. If data at the sub-application level is not available from either source, activity data at the application level should be obtained and applied using Equation 7.6 (Tier 1a).

Since the lifetime of the product is assumed to be no more than two years, any amount not emitted during the first year must by definition be emitted during the second and final year. In reality, most emissions occur within the first year after product purchase, but Equation 7.6 rightly accounts for the lag period between the time of manufacture and the time of purchase and use. When applying Equation 7.6, however, care must be taken to define the Point of Sale which, for the purposes of emission estimation, is viewed as sales by the manufacturer to

11 HFC-43-10mee is used solely as a solvent, but is counted as an aerosol when delivered through aerosol canisters.

the supply chain and not by the retailer to the end-user. This approach is most appropriate because sales data will normally be collected from manufacturers and major distributors.

In contrast with the situation for solvents, there is rarely a need to account for recovery, recycling or destruction, since this is only likely to occur when stockpiled product becomes out-of-date. Under normal supply-chain management conditions this is a rare event.

A decision tree for estimating actual emissions is included in Figure 7.3, Decision Tree for Actual Emissions from the Aerosol Application. The data collection process is described below.

Figure 7.3 Decision tree for actual emissions from the aerosol application

Figure 7.3 Decision tree for actual emissions from the aerosol application

Box 1: Tier 1a

Note:

1. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited resources), for discussion of key categories and use of decision trees.

Box 1: Tier 1a

Note:

1. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited resources), for discussion of key categories and use of decision trees.

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