1. 1 HOW DO WE KNOW IF THE WASHINGTON AREA WILL ATTAIN? The State Implementation Plan (SIP) under development must give EPA the answer to three basic questions: 1)Are we making progress towards our goal? (the Rate of Progress test) 2)Will we reach our goal in time? (the Attainment and Weight of Evidence tests) 3)What do we need to do to make sure we get there? (what is our Air Quality Plan?) Plan Progress Attainment 1) ARE WE MAKING PROGRESS TOWARDS OUR GOAL? EPA requires all regions trying to meet the ozone standard to reduce emissions by a minimum amount every year. Every three years, each region submits a new plan showing how it will reduce emissions during the next three years. These plans are called “Rate of Progress” plans. The plan needs to show that volatile organic compound (VOC) emissions will be reduced by at least 9% over a three year period. (EPA will also accept a plan that shows reductions in nitrogen oxides (NOx) instead of some of the VOC.) Because the Washington region wasn’t required to submit a plan for the years 1999- 2002 before, our new SIP needs to include two rate-of-progress demonstrations: one for 1999-2002, and one for 2002-2005. HOW DO WE CALCULATE a Rate of Progress? We need to determine THREE things: What level of emissions did we start with? How much do we have to reduce? Does our plan create the reductions we need? MWAQC BRIEFING PREPARED BY COG DEPARTMENT OF ENVIRONMENTAL PROGRAMS Based on Preliminary Data March 18, 2003

2. 2 What Level of Emissions Did We Start With? Because 1990 was the first year that regions were required to show progress towards an attainment date, it is the base year for all the rate of progress calculations. Therefore, the 1990 inventory is also referred to as the BASE YEAR INVENTORY. The 1990 inventory catalogues emissions from every man-made source of NOx and VOC. Sources are placed into four categories: stationary sources, mobile sources, area sources and nonroad sources. Because the 1990 inventory was created many years ago, the mobile source portion of the inventory was based on estimates from an old mobile emissions model. EPA is requiring us to recalculate the mobile portion of our 1990 inventory using new modeling techniques before we begin our rate of progress calculations for the new SIP. The BASE YEAR INVENTORY tells us how many tons of ozone precursors were being emitted on an average summer day in 1990. This inventory forms the starting point for all of our rate of progress calculations. How big is the BASE YEAR INVENTORY? Our current estimate is: VOCNOx 566.8 tpdAND872.8 tpd

3. 3 A TARGET INVENTORY is created for each rate of progress demonstration. The inventory tells us the maximum number of tons the region can emit at the end of the three year period and still make rate of progress. The inventories are named for the last year in the rate of progress demonstration (which is also referred to as a milestone or target year.) Hence, the 2002 TARGET INVENTORY refers to the maximum emissions at the end of the 1999-2002 rate of progress period. How Much Do We Have To Reduce? EPA says that regions need to reduce emissions by 9% over each three year period. However, the calculation isn’t as simple as it sounds. There are a lot of steps involved in calculating the TARGET INVENTORIES, which tell us the maximum level of emissions allowable for a rate of progress demonstration. Why are there so many steps in calculating a TARGET INVENTORY? There are two reasons. First, EPA doesn’t let us take credit for every ton of emissions that has been reduced since 1990. Two federal programs in place before 1990 have continued to reduce emissions today. (The Federal Motor Vehicle Control Program (FMVCP) reduces emissions from motor vehicles, and the Reid Vapor Pressure (RVP) program reduces emissions from evaporation of gasoline.) EPA won’t let us take credit for those programs in our ROP demonstration. So, we need to calculate the benefits of those programs and subtract them out. We do this by creating an ADJUSTED INVENTORY for the target year. We subtract this inventory from the BASE YEAR INVENTORY to calculate the benefit from the two federal programs. So an adjusted inventory isn’t a final product – it’s one piece of the TARGET INVENTORY puzzle.

4. 4 How big are the TARGET YEAR INVENTORIES? Our current estimates are: YearVOCNOx 1996 381.0 N/A 1999 355.7 718.8 2002 342.9 628.7 2005 335.1 541.2 The second thing we need to know is the size of the TARGET INVENTORY from the last rate of progress. We need this in order to figure out how big a 9% reduction really is. So, we need the 1999 TARGET INVENTORY to calculate the 2002 rate of progress…but first we need the 1996 TARGET INVENTORY to calculate the target for 1999. The federal FMVCP and RVP programs lowered vehicle emission rates. An ADJUSTED INVENTORY tells us what 1990 emissions would have been if the cars on the road in 1990 had shown the same emission reductions from these two federal programs as cars on the road in the target year.

5. 5 Does Our Plan Create the Reductions We Need? Once we know what our rate of progress target is, we can figure out how our expected emission levels compare to that target. To figure out what our expected emission levels are, we calculate a CONTROLLED INVENTORY. We then compare the controlled inventories to the target inventories to show that we’ve met rate of progress. A CONTROLLED INVENTORY is developed for each milestone year. It estimates how many tons of ozone precursors we had or will have in a given year, including reductions from all control measures. How big are the CONTROLLED INVENTORIES? YearVOCNOx 2002371.4609.8 2005 352.3486.5

6. 6 How big is the photochemically MODELED ATTAINMENT INVENTORY? VOCNOx 359.7AND515.3 We compare the MODELED ATTAINMENT INVENTORY to our 2005 CONTROLLED INVENTORY (also used for Rate of Progress) and use WEIGHT OF EVIDENCE to show that we will attain the ozone standard by the deadline. WEIGHT OF EVIDENCE allows us to use actual air quality data collected from regional ozone monitors to demonstrate that ozone levels in the region are declining in accordance with the air quality plan. 2) WILL WE REACH OUR GOAL IN TIME? The second component of the SIP demonstrates that we will attain the federal one hour ozone standard. To answer the question “Will we attain in time?”, we first need to know the goal. We use photochemical modeling to figure out what level of ozone- causing emissions we can have and still attain the federal ozone standard. We model atmospheric conditions and emission levels during specific days our region exceeded the ozone standard (referred to as episodes). This modeling enables us to determine the maximum allowable amount of emissions. The MODELED ATTAINMENT INVENTORY was created in 1999. It tells us the maximum number of tons of ozone precursors the region can emit on a summer day while attaining the ozone standard.

7. 7 3) WHAT DO WE NEED TO DO TO MAKE SURE WE GET THERE? The Washington region already has control measures in place to reduce ozone emissions. But, after all the calculations, it may appear that these measures won’t reduce emissions enough for us to attain the ozone standard in 2005. If we cannot demonstrate either ATTAINMENT or RATE OF PROGRESS, or our WEIGHT OF EVIDENCE demonstration does not show a decrease in actual ozone levels, we will need to select additional measures to further reduce emissions. These measures can come from the stationary, mobile, area or nonroad source sectors, and may be voluntary or mandatory. They will be used to reduce the controlled inventory so we can attain the ozone standard. There is always a chance that despite all of our efforts, something will prevent us from demonstrating rate of progress or meeting the ozone standard by our deadline (November 15, 2005). We are required to identify contingency measures so we can take action if this happens. Contingency measures need to provide reductions equal to at least 3% of the TARGET INVENTORY. They must go into effect immediately if we fail to demonstrate Rate of Progress or fail to demonstrate attainment by the deadline. All information current as of March 18, 2003

8. 8 InventoryVOCNOx 2002 Controlled 371.4609.8 2002 Target342.9628.7 Key Inventories for 2002 Rate of Progress as of March 18, 2003 InventoryVOCNOx 2005 Controlled 352.3486.5 2005 Target335.1541.2 Key Inventories for 2005 Rate of Progress as of March 18, 2003