; bears to (II) the primary national ambient air quality standard for ozone established by the Administrator under 109(b) of the Clean Air Act ( 42 U.S.C. 7409(b) ). (ii) Special rule If the average of design values from 2013–2015 and 2016–2018 is not greater than the primary national ambient air quality standard for ozone, a weighting factor of zero is applied. (iii) Maximum factor Notwithstanding clauses (i) and (ii), the maximum factor to be applied for ozone shall not exceed 1.4. (D) Design values of fine particulate matter (i) In general For counties with design values of fine particulate matter greater than the national ambient air quality standards, the population of a monitored county is multiplied by the greater factor of— (I) the average of the 2013–2015 and 2016–2018 design values for annual concentrations of fine particulate matter, provided by the Environmental Protection Agency Administrator; bears to (II) the primary national ambient air quality standard for fine particulate matter for annual concentrations established by the Administrator under 109(b) of the Clean Air Act ( 42 U.S.C. 7409(b) ); or (III) the average of the 2013–2015 and 2016–2018 design values for 24-hour averaging time of fine particulate matter, provided by the Environmental Protection Agency Administrator