The ambient air quality data is used to verify compliance with state and national ambient air quality standards, to support development of regulations designed to reduce ambient air pollution, to assess the effectiveness of existing air pollution control strategies, and to provide aerometric data for special research. The national ambient air quality standards (NAAQS) are listed in Table 2.

TABLE 1: 1997 MADEP MONITORING SITE DIRECTORY

1997 MADEP MONITORING SITE DIRECTORY

1997 MADEP MONITORING SITE DIRECTORY

TABLE 2: STATE AND NATIONAL AMBIENT AIR QUALITY STANDARDS (NAAQS)

Primary standards protect against adverse health effects. Secondary standards protect against welfare effects such as damage to crops, vegetation, and buildings.

Standards other than those based upon the annual arithmetic mean must not be exceeded more than once a year.

^A The 1-hour O3 standard applies only to areas that were designated non-attainment when the 8-hour O3 standard was adopted in July 1997. To attain the 1-hour O3 standard, the daily maximum 1-hour average concentration must not exceed 0.12 ppm more than once a year, averaged over 3 consecutive years.

^B To attain the 8-hour O3 standard, the 3-year average of the fourth-highest daily maximum 8-hour average over each year must not exceed 0.08 ppm.

^C To attain the PM-10 annual standard, the arithmetic average of the 24-hour samples for a period of 1 year, averaged over 3 consecutive years, must not exceed 50 mg/m³.

^D To attain the PM-10 24-hour standard, the 99th percentile of the distribution of the 24-hour concentrations for a period of 1 year, averaged over 3 years, must not exceed 150 mg/m³ at each monitor within an area.

^E To attain the PM-2.5 annual standard, the 3-year average of the annual arithmetic mean of the 24-hour concentration from single or multiple population oriented monitors must not exceed 15.0 mg/m³.

^F To attain the PM-2.5 24-hour standard, the 98th percentile of the distribution of the 24-hour concentrations for a period of 1 year, averaged over 3 years, must not exceed 65 mg/m³ at each monitor within an area.

mg/m³ = micrograms per cubic meter; ppm = parts per million; mg/m³ = milligrams per cubic meter

Attainment of Air Quality Standards
Areas not meeting the NAAQS are designated as "non-attainment" areas. Massachusetts is classified as being in "serious" non-attainment for ozone (O3) statewide. There are also some specific communities which are designated non-attainment for carbon monoxide (CO).

The federal Clean Air Act requires that states which are in non-attainment develop and implement strategies for attaining the standard. The State Implementation Plan (SIP) is the mechanism for documenting this process, and all revisions to the SIP must be approved by the U.S. EPA. The following list contains the measures that have been submitted to U.S. EPA since 1993 as part of Massachusetts? "Reasonable Further Progress" toward attainment. These serve as milestones which help document the progress toward meeting the O3 standard. Please note that this is not a comprehensive list of air regulations, as there are many DEP air regulations that are not specifically credited in the Reasonable Further Progress SIPs. Additional measures needed to meet the standard will be delineated in an Attainment Demonstration submittal, which DEP plans to submit to EPA in 1998.

List of Air Pollution Control Programs in Massachusetts for Reasonable Further Progress Toward Attainment of the One-Hour Ozone Standard (regulatory citations are in parentheses)

Stationary Point Source Controls:

• Reasonably Available Control Technology (RACT) for 50 Ton VOC Sources (310 CMR 7.18)
  
• RACT for 50 Ton NOx Sources (310 CMR 7.19)

Stationary Area Source Controls:

• Reformulated Architectural and Industrial Maintenance Coatings (310 CMR 7.25)
  
• Reformulated Traffic Markings (310 CMR 7.25)
  
• Reformulated Consumer and Commercial Products (310 CMR 7.25)
  
• Automotive Refinishing Controls (310 CMR 7.18)

On-Road Mobile Source Controls:

• Stage II Vapor Recovery Systems at Gasoline Stations (310 CMR 7.24)
  
• Federal Reformulated Gasoline
  
• Enhanced Automobile Inspection and Maintenance (I/M) up to 10,000 Gross Vehicle Weight Rating (310 CMR 60.02 - pending rewrite)
  
• Low Emission Vehicle (LEV) Program (310 CMR 7.40)
  
• Federal Motor Vehicle Program (FMVCP) - Pre-Clean Act New Engine Performance Standards
  
• Federal Tier I New Engine Performance Standards
  
• Traffic Flow Improvements

Off-Road Mobile Source Controls:

• Federal Reformulated Gasoline for Off-Highway Equipment
  
• Federal New Engine Performance Standards for Off-Highway Equipment

Massachusetts has made significant progress in attainment of the CO standard through the implementation of air pollution control programs. The last violation of the CO NAAQS occurred in Boston in 1986. The Boston area was redesignated as in attainment of the CO federal air quality standard by the U.S. EPA in 1996. Springfield, Worcester, Lowell, and Waltham will remain in non-attainment for CO, though there has been significant improvement, until studies and analyses support a request for redesignation.

1997 1-Hour Ozone Exceedances
The ozone one hour standard of 0.12 ppm was exceeded at three sites, in Chicopee, Fairhaven, and Ware, out of the sixteen sites at which ozone was monitored during 1997. There were four exceedance days (days ozone exceedances occurred) during the year. Figure 1 shows the ten year trends for number of exceedance days and total ozone exceedances.

The 1-hour ozone air quality standard is attained when expected exceedances of the 0.12 ppm standard are less than or equal to 1 per year at a site as averaged over a three year period. Figure 2 shows the expected annual O3 exceedances for the periods 1994-1996 and 1995-1997.

1-Hr O3 Exceedance Days & Total Exceedances 1988 to 1997

Ozone exceeded the 1-Hour standard (0.125 ppm)

figure 1

3 Year Average of Expected Annual 1-Hr O3 Exceedances

(if greater than 1 site is in violation)

< that for non-attainment? 2B? Figure>

The 8-hour standard provides increased health protection against longer exposure periods. Studies indicate that adverse health effects result from prolonged (6 to 8 hour) exposures to O3 at concentrations below the level of the 1-hour standard of 0.12 ppm. The 8-hour standard of 0.08 ppm is designed to lessen adverse O3-related health effects, such as respiratory symptoms and decreased lung function.

Figures 3 and 4 depict the levels in recent years for an 8-hour standard, had it applied to Massachusetts. These are for reference only. Measurements taken during the three-year period from 1997 through 1999 will be used to determine attainment status relative to the 8-hour standard.

3-Year Average of Annual 4th Highest Daily Maximum 8-Hr O3 Average

Exceedances of the 8-hour standard* (0.085 ppm)

< produce conditions right the under sunlight with reaction in precursors? ozone 10? 9? 8? 7? 6? 5? 4?>

The initial requirement of the SIP included a 1990 base year emissions inventory for ozone precursors and CO, from which control programs were developed. Emission inventories are required to be submitted every three years to EPA. The 1990 emissions estimates, 1993 preliminary emissions estimates, and the projected 1996 emissions were submitted to EPA as part of the SIP process. The numbers reported here reflect the most recent SIP revision from March, 1997.

Sulfur dioxide emissions are tracked annually by DEP because of the requirements of the 1985 State Acid Rain (STAR) program. The STAR program is more stringent than the national program because it imposes an emissions cap of 412,000 tons which is based on the average annual emissions during the four year period of 1979 - 1982. If this cap is exceeded DEP is required to implement additional control measures. The SO2 cap has never been exceeded in the state since the inception of the STAR program.

Point Source Emissions Trends
The point source section of the inventory comprises the large industrial polluters and is the only category in which actual data is available for all seven years. The point source emissions are presented in Figures 11 and 12. The electric utility emissions (Figure 13) are presented because they comprise the major proportion of NOx and SO2 point source emissions.

VOC and CO Point Source Emissions 1990 - 1996

figure 11

SO2 and NOx Point Source Emissions 1990 - 1996

figure 12

SO2 and NOx Electric Utility Emissions 1990 - 1996

figure 13

Total VOC Emissions
Total VOC emissions were projected to be reduced from 986 tons per summer day (TPSD) in 1990 to 731 TPSD in 1996 (Figure 14). This 26% reduction was projected to occur net of economic and industrial growth and is based on the 1990 to 1996 controls that DEP was to have implemented to meet the first set of milestone reductions required under the 1990 Clean Air Act Amendments.

The 1996 emission estimates for VOC and other precursors are based on projected controls from all programs that were included in the 15% Reasonable Further Progress SIP, which required reductions by 1996. Although the Enhanced Inspection and Maintenance program for motor vehicles will be implemented beginning in 1999, the 1996 projected emissions reflect reductions from the program.

The emission reductions are also attributable to other control measures such as: Federal Motor Vehicle Control Program (FMVCP); Reasonable Available Control Technology (RACT) corrections for point sources; Stage II vapor recovery for gasoline stations; architectural coatings (i.e., lower paint emissions); and, reformulated gasoline (i.e., lower volatility).

Overall, there is a substantial projected emissions reduction for all four pollutants from 1990 to 1996, even though there has been significant growth in population and economic activity in Massachusetts. The projected reductions in total statewide emissions for each of the following pollutants from 1990 to 1996 are:

VOC.................. -26% (see figure 14)

NOx................... -27% (see figure 15)

SO2.................... -41%

CO...................... -47%

Composite VOC Emissions 1990 - 1996

(1996 projected)

Total NOX Emissions
NOx emissions (Figure 15) are projected to be reduced from 934 TPSD in 1990 to 684 TPSD in 1996. This 27% reduction is based on NOx point source emission controls in conjunction with the above mentioned on-road mobile source I/M and FMVCP controls.

Composite NOx Emissions 1990 - 1996

(1996 projected)

figure 15

On-Road Mobile Source Emissions
Substantial reductions of on-road mobile VOC and NOx emissions are shown (Figure 16) with a contrasting increase in daily vehicle miles traveled (DVMT). The projected trends from 1990 to 1996 are:

VOC.................. -53%

NOx.................... -28%

DVMT............... +3%

On-Road Mobile Emissions and DVMT

(1996 projected)

figure 16