(DVF)I = the estimated future design value for the time attainment is required, ppb or ug/m3.
Equation (3.1) looks simple enough. However, several issues must be resolved before
(1) How is a “site-specific” baseline design value ((DVB)I) calculated?
(2) In calculating the (RRF)I , what do we mean by “near” site I?
(3) Several surface grid cells may be “near” the monitor, which one(s) of these should be used to
calculate the (RRF)I ?
(4) How do you calculate future design values in unmonitored areas?
(5) Which base year emissions inventory should be projected to the future for the purpose of
(6) Which future year should emissions be projected to in order to assess attainment using the
modeled attainment test?
3.1 Calculating site-specific baseline concentrations.
The modeled attainment test is linked to the form of the ozone and PM2.5 NAAQS
through the use of monitored design values. Official design values are calculated in different
ways for 8-hour ozone, annual average PM2.5, and 24-hour average PM2.5. The following is a
brief description of the calculations:
The 8-hour ozone design value is calculated as the 3 year average of the fourth highest
monitored daily 8-hour maximum value at each monitoring site. The standard is met if the
design value is <0.8 ppm (in practice, this translates to < 85 ppb). The detailed description of the
methodology can be found in 40 CFR Part 50.10, and Appendix I to Part 50.
Annual Average PM2.5
The annual average PM2.5 standard is met if, over a consecutive three year period, the average
arithmetic mean concentration of PM2.5 is less than or equal to 15.0 :g/m3. The annual
arithmetic mean at a monitoring site is calculated by averaging the four quarterly arithmetic
mean concentrations observed during a calendar year at the site. The annual mean concentration
averaged over three years must be < 15.0:g/m3 at all monitoring sites. The details can be found
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castellano: DISPER CUSTIC DESCAR RADIA italiano:
deutsch: DIS CUS DES RAD
castellano: DIS CUS DES RAD english: DIS CUS DES RAD
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