(a) To demonstrate compliance with the PWR limits presented in Table 1 of this subpart, you must calculate the PWR for each coating as described in paragraphs (a)(1) through (2) of this section:

(1) Calculate the weighted reactivity factor (WRF) for each propellant and coating component using Equation 1:

(2) Calculate the PWR of each product using Equation 2:

(b) In calculating the PWR, you must follow the guidelines in paragraphs (b)(1) through (b)(4) of this section.

(1) Any ingredient which does not contain carbon is assigned a RF value of 0.

(2) Any aerosol coating solid, including but not limited to resins, pigments, fillers, plasticizers, and extenders is assigned a RF of 0. These items do not have to be identified individually in the calculation.

(3) All individual compounds present in the coating in an amount equal to or exceeding 0.1 percent will be considered ingredients regardless of whether or not the ingredient is reported to the manufacturer.

(4) All individual compounds present in the coating in an amount less than 0.1 percent will be assigned an RF value of 0.

(5) Any component that is a VOC but is not listed in Table 2A, 2B, or 2C of this subpart is assigned an RF value as detailed in paragraph (e) of this section.

(c) You may use either formulation data (including information for both the liquid and propellant phases), CARB Method 310 (2018) (incorporated by reference, see § 59.515), or EPA's Method 311 (40 CFR part 63, appendix A), to calculate the PWR. However, if there are inconsistencies between the formulation data and the CARB Method 310 (2018) or EPA Method 311 results, the CARB Method 310 (2018) or EPA Method 311 results will govern.

(d) If you manufacture a coating containing either an aromatic or aliphatic hydrocarbon solvent mixture, you must use the appropriate RF for that mixture provided in table 2B or 2C to this subpart when calculating the PWR using formulation data. However, when calculating the PWR for a coating containing these mixtures using data from CARB Method 310 (2018) (incorporated by reference, see § 59.515), or EPA Method 311—(40 CFR part 63, appendix A), you must identify the individual compounds that are present in the solvent mixture and use the weight fraction of those individual compounds and their RF from table 2A to this subpart in the calculation.

(e) The Reactivity Factor (RF) is assigned according to paragraphs (e)(1) through (4):

(1) If a VOC is used in a product and listed in table 2A, 2B, or 2C to this subpart, then the assigned RF shall be used;

(2) If a product contains a mixture and/or multiple isomers of a VOC, the highest RF of the mixture or multiple isomers from table 2A to this subpart shall be used;

(3) If a VOC is used in a product but not listed in table 2A to this subpart, but more than one isomer or mixtures of isomers of the VOC is listed in table 2A to this subpart, then the highest RF associated with the listed isomers or isomer mixtures shall be used; and

(4) If a VOC is used in a product but not listed in table 2A to this subpart, the assigned default RF of 18.50 g O3 /g VOC shall be used.

(f) In calculating the PWR value for a coating containing an aromatic hydrocarbon solvent with a boiling range different from the ranges specified in Table 2C of this subpart, you must assign an RF as described in paragraphs (f)(1) and (f)(2) of this section:

(1) If the solvent boiling point is lower than or equal to 420 degrees F, then you must use the RF in Table 2C of this subpart specified for bin 23;

(2) If the solvent boiling point is higher than 420 degrees F, then you must use the RF specified in Table 2C of this subpart for bin 24.

(g) For purposes of compliance with the PWR limits, all compounds listed in Tables 2A, 2B, or 2C that are used in the aerosol coating products must be included in the calculation. This includes compounds that may otherwise be exempted from the definition of VOC in § 59.100(s).

(h) Until July 17, 2025 the test methods listed in table 3 of appendix A to subpart E of part 59 are applicable to this subpart.