Reference or equivalent method for measuring PM2.5. Therefore, for regional haze calculations,

it is not necessary to use the speciated data adjustment procedures introduced in Section 3 (the

“SANDWICH” adjustments).

Sisler (1996) has developed a set of default assumptions75 for mass associated with each

of the components of particulate matter for Equation (6.1). These are presented in Table 6.1.

The components in Table 6.1 are similar to those used in the modeled attainment demonstrations

for the PM2.5 NAAQS. Notice however, that sulfate and nitrate mass are assumed to be fully

neutralized (therefore, ammonium is not needed as a separate component); organic carbon is

assumed to be equal to 1.4 times measured OC mass (1.8 times OC in the new IMPROVE

equation); there is no water component; and there is a term for coarse particulate matter.

Table 6.1. Default Assumptions Used To Derive Aerosol Species Concentrations For

Estimating Extinction Coefficients

75The default assumptions in table 6.1 are applicable to the “old” IMPROVE equation.

The new IMPROVE equation assumes that OCM= 1.8 x [OC] and sea salt = 1.8 x [chloride].

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castellano: DISPER CUSTIC DESCAR RADIA italiano:

castellano: DIS CUS DES RAD english: DIS CUS DES RAD

português: DIS CUS DES RAD italiano: DIS CUS DES RAD