## CHAPTER 2

AIR QUALITY AND HEAL TH EFFECTS

Introduction

Ambient Air Quality Standards

Comparison to Other U.S. Areas

Current Air Quality SummaryChapter 2 Air Quality and Health Effects

2

- 1 

### INTRODUCTION

In this chapter, 1995 air quality in the South Coast Air Basin (Basin), and in the portions of the M ojave Desert and Salton Sea Air Basins (MDAB/SSAB) monitored by the South Coast Air Quality Management District (District), is compared to state and federal ambient air quality standards. (The MDAB and SSAB were part of the Southeast Desert Air Basin or S EDAB until May 30, 1996, when the California Air Resources Board adopted the boundaries and names of the two new air basins.) For those pollutants which exceeded federal standards, maps which compare 1995 air quality in different areas of the Basin have b een included.

Nationwide air quality for 1994 is also briefly summarized in this chapter. A comparison of air quality in the Basin to other U.S. and California urban areas is presented in the following pages.



### AMBIENT AIR QUALITY STANDARDS

Ambient air qual ity standards for ozone, carbon monoxide, nitrogen dioxide, sulfur dioxide, particulate matter (PM 10 ), and lead have been set by both the California state and federal governments. The state has also set standards for sulfate and visibility. The ambient a ir quality standards for each of these pollutants and their effects on health are summarized in Table 2

- 1

.
In 1995 the Basin exceeded the federal standards for ozone, carbon monoxide, and PM 10 on a total of 116 days. In recent years the Basin has recorded many more days exceeding the federal standards than any other area of the U.S.



### COMPARISON TO OTHER U.S. AREAS

The Basin’s severe air pollution problem is a consequence of the combination of emissions from the nation’s second largest urban area and especia lly adverse meteorological conditions. The average wind speed for Los Angeles is the lowest of the nation’s ten largest urban areas. In addition, the summertime maximum mixing height (an index of how well pollutants can be dispersed vertically in the atm osphere) in Southern California averages the lowest in the U.S. The Southern California area is also an area with abundant sunshine, which drives the photochemical reactions which form pollutants such as ozone.FINAL 1997 AQMP

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- 2 TABLE 2

- 1 Ambient Air Quality Standards

ST ATE STANDARD FEDERAL PRIMARY

STANDARD MOST RELEVANT EFFECT S

AIR

POLLUTANT CONCENTRATION/

AVERAGING TIME CONCENTRATION/

AVERAGING TIME

Ozone 0.09 ppm, 1

- hr. avg. > 0.12 ppm, 1

- hr avg.> (a) Short

- term exposures: (1) Pulmonary function decrements and loca lized lung edema in humans and animals. (2) Risk to public health implied by alterations in pulmonary morphology and host defense in animals; (b) Long

- term exposures: Risk to public health implied by altered connective tissue metabolism and altered pulmo nary morphology in animals after long

- term exposures and pulmonary function decrements in chronically exposed humans; (c) Vegetation damage; (d) Property damage

Carbon Monoxide 9.0 ppm, 8

- hr avg. >

20 ppm, 1

- hr avg. > 9 ppm, 8

- hr avg.> 35 ppm, 1

- hr avg.> (a) Aggravation of angina pectoris and other aspects of coronary heart disease; (b) Decreased exercise tolerance in persons with peripheral vascular disease and lung disease; (c) Impairment of central nervous system functions; (d) Possible increased risk to fetuses
Nitrogen Dioxide 0.25 ppm, 1

- hr avg. > 0.053 ppm, ann. avg.> (a) Potential to aggravate chronic respiratory disease and respiratory symptoms in sensitive groups; (b) Risk to public health implied by pulmonary and extra

- pulmonary biochemical and cellular changes and pulmonary structural changes; (c) Contribution to atmospheric discoloration

Sulfur Dioxide 0.04 ppm, 24

- hr avg.>

0.25 ppm, 1

- hr. avg. > 0.03 ppm, ann. avg.> 0.14 ppm, 24

- hr avg.> (a) Bronchoconstriction accompanied by symptoms whic h may include wheezing, shortness of breath and chest tightness, during exercise or physical activity in persons with asthma
Suspended Particulate Matter (PM 10 ) 30 μg/m 3 , ann. geometric mean >

50 μg/m 3 , 24

- hr average> 50 μg/m 3 , annual arithmetic mean >

15 0μg/m 3 , 24

- hr avg.> (a) Excess deaths from short

- term exposures and exacerbation of symptoms in sensitive patients with respiratory disease; (b) Excess seasonal declines in pulmonary function, especially in children

Sulfates 25 μg/m 3 , 24

- hr avg. >= (a ) Decrease in ventilatory function; (b) Aggravation of asthmatic symptoms; (c) Aggravation of cardio

- pulmonary disease; (d) Vegetation damage; (e) Degradation of visibility; (f) Property damage

Lead 1.5 μg/m 3 , 30

- day avg. >= 1.5 μg/m 3 , calendar quarter> ( a) Increased body burden; (b) Impairment of blood formation and nerve conduction
Visibility

Reducing Particles In sufficient amount such that the

extinction coefficient is greater than 0.23 inverse kilometers (to reduce the visual range to less than 10

m iles) at relative humidity less than 70 percent, 8

- hour average (10am

- 6pm) Visibility impairment on days when relative humidity is less than 70 percentChapter 2 Air Quality and Health Effects

2

- 3 In the Basin, exceedances of the federal ozone standard are recorded largely during the spring to e arly fall months. By contrast, exceedances of the federal carbon monoxide standard occur in late fall and winter. Exceedances of the federal 24

- hour PM 10 standard can occur throughout the year, but occur most frequently in fall and winter. Although ther e are changes in emissions by season, the observed variations in pollutant concentrations are largely a result of seasonal differences in weather conditions.

In 1995, the federal standard for ozone was exceeded at one or more Basin locations on 27 percent of days and the federal carbon monoxide standard was exceeded on 4 percent of days. The federal PM 10 standard was exceeded on 10 percent of the days sampled

. 1

Figure 2

- 1 shows maximum pollutant concentrations in 1994 for the South Coast Air Basin compared to other urban areas in the U.S. and California. Maximum concentrations in these other large U.S. urban areas exceeded the federal ozone and PM 10 standards in some instances, and did not exceed the carbon monoxide standard. However several other areas i n the country did report exceedances of the carbon monoxide standard. In California, some of the other large urban areas also exceeded the PM 10 and ozone standards, but did not exceed the carbon monoxide standard.

The maximum second highest 1

- hour averag e ozone concentration in the Basin was nearly twice the federal standard. New York and Houston exceeded by much less of a margin, and Philadelphia and Washington barely exceeded, while Chicago did not exceed the standard. Though New York is a much larger urban area than Houston, the maximum ozone concentration for Houston equaled that of New York. Houston, like Los Angeles, is an area with abundant sunshine which creates favorable conditions for the photochemical reactions that yield ozone and other phot ochemical pollutants. In California, San Francisco did not exceed the ozone standard, while the San Diego, Sacramento and Oxnard

- Ventura metropolitan areas each exceeded the standard. Both the San Diego and Oxnard

- Ventura metropolitan areas are subject t o higher ozone levels due to transport from the South Coast Air Basin.

The maximum 8

- hour average carbon monoxide concentration in the Basin was over one and a half times the federal standard. The standard was not exceeded in the other major urban areas d epicted in Figure 2

- 1 in this comparison.

Maximum annual average PM 10 concentrations recorded in the Basin, New York, and Philadelphia exceeded the federal PM 10 standard, and San Diego exceeded very narrowly. Only Philadelphia recorded a higher PM 10 tha n the Basin, as a consequence of nearby stationary source emissions.

1 PM 10 is sampled every sixth day, unlike the gaseous pollutants such as ozone and carbon m onoxide which are sampled continuously.FINAL 1997 AQMP

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- 4 A) U.S. Metropolitan Areas Compared to the South Coast Air Basin

B) California Metropolitan Areas Compared to the South Coast Air Basin

FIGURE 2

- 1 1994 Air Quality Maximum Pollutant Concentrations as Percentages of the Federal Standard

In 1994, no location in the Basin or any other area of the U.S. exceeded the nitrogen dioxide standard. The Los Angeles County portion of the Basin was the last area of the U.S. to exceed the standard , but has remained in compliance since 1991. Sulfur dioxide concentrations in the Basin continued to remain well below federal standards, and were lower than those in the urban areas of the Eastern U.S. Concentrations of sulfur dioxide in urban areas in the Eastern U.S. have generally been higher than those in the Basin due to the use of fuels such as coal which have relatively high sulfur content.



### CURRENT AIR QUALITY SUMMARY

Figure 2

- 2 shows the maximum pollutant concentrations for 1995 as percentages of the state and federal standards. The maximum ozone concentration exceeded the federal standard by the widest margin, with a maximum 1

- hour average (0.26 ppm recorded in the Central San Bernardino Mountain area) that was 200 percent of the federal standar d. The highest 8

- hour average carbon monoxide concentration recorded (13.86 ppm in the South Central Los Angeles County area) was 146 percent of the federal carbon monoxide standard. The maximum 24

- hour average PM 10 (219 μg/m 3 in the Metropolitan Riversi de County area) was 145 percent of the federal 24

- hour standard, and the maximum annual average PM 10 (69 μg/m 3 recorded in Metropolitan Riverside County) was 138 percent of the federal annual PM 10 standard. The maximum sulfate concentration (26.3 μg/m 3 in Metropolitan Riverside County) was 105 percent of the state sulfate standard.

Concentrations of other pollutants remained below the standards. The maximum annual average nitrogen dioxide concentration (0.0464 ppm in the East San Gabriel Valley andChapter 2 Air Quality and Health Effects

2

- 5 Northw est San Bernardino Valley areas) was 87 percent of the federal standard, while the maximum annual average sulfur dioxide concentration (0.0030 ppm in South Central Los Angeles County) was 10 percent of the federal standard. The maximum quarterly average l ead concentration recorded at any District air monitoring station was 4 percent of the federal standard. However, higher concentrations of lead (40 percent of the standard) were recorded at special monitoring locations immediately adjacent to stationary s ources.
Figure 2

- 3 shows the percent of days on which the federal and state standards were exceeded in 1995 at the Basin locations which exceeded most frequently. The federal ozone standard was exceeded on a maximum of 20 percent of days (in the East San Gabriel Valley area of Los Angeles County), and the federal carbon monoxide standard was exceeded on a maximum of 4 percent of days (in South Central Los Angeles County). Exceedances of the federal 24

- hour PM 10 standard were recorded on a maximum of 7 per cent of days sampled (Metropolitan Riverside County), while the state sulfate standard was exceeded on a maximum of 2 percent of days sampled (Metropolitan Riverside County).

FIGURE 2

- 2

1995 Maximum Pollutant Concentrations as Percent of Federal and State StandardsFINAL 1997 AQMP

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- 6 FIGURE 2

- 3 1995 Percent of Days/Months/Quarters Exceeding Federal and State Standards at Most Affected Locations

Detailed analyses of current air quality and statistics for all monitoring areas are contained in Appendix II . The following sect ions present summary information on health effects and how frequently, and by how much of a margin, different areas of the Basin and MDAB/SSAB exceeded the federal and state ambient air quality standards in 1995.



### Ozone (O 3 

### ) Specific Information

Health Effe cts

Individuals exercising outdoors, children and people with preexisting lung disease such as asthma and chronic pulmonary lung disease are considered to be the most susceptible sub

- groups for ozone effects. Short

- term exposures (lasting for a few hours) to ozone at levels typically observed in Southern California can result in breathing pattern changes, reduction of breathing capacity, increased susceptibility to infections, inflammation of the lung tissue, and some immunological changes. In recent year s, a correlation between elevated ambient ozone levels and increases in daily hospital admission rates, as well as mortality, has also been reported.

Ozone exposure under exercising conditions is known to increase the severity of the above mentioned observ ed responses. Similarly, animal studies suggest that exposures to a combination of pollutants which include ozone is more toxic than exposure to ozoneChapter 2 Air Quality and Health Effects

2

- 7 alone. Although lung volume and resistance changes observed after a single exposure diminish with repea ted exposures, biochemical and cellular changes appear to persist, which can lead to subsequent lung structural changes. The cancer causing potential of ozone exposure identified in some studies needs further evaluation to draw any definitive conclusions.

Air Quality

In 1995, the South Coast Air Quality Management District monitored ozone concentrations at 33 locations in the Basin and MDAB/SSAB. In the Basin, the maximum ozone concentration (0.26 ppm recorded in the central San Bernardino Mountain area) was 200 percent of the federal standard and 260 percent of the state standard. Los Angeles, Riverside and San Bernardino Counties had maxima above the stage I episode level (0.20 ppm). Ozone concentrations at Orange County locations remained below the e pisode level, but the maximum exceeded the health advisory level (0.15 ppm). Table 2

- 2 shows maximum ozone concentrations by Basin and County.

Maximum ozone concentrations in the MDAB/SSAB areas monitored by the District were lower than in the Basin. How ever, the maximum concentration in the Riverside County SSAB (0.16 ppm in the Coachella Valley area) still exceeded the health advisory level.

TABLE 2

- 2

1995 Maximum Ozone Concentrations by Basin and County

Basin/County Maximum

1

- Hr Avg. ppm Percent of

Fed eral Standard Area

South Coast Air Basin Los Angeles Co. 0.22 169 East San Gabriel Valley Orange Co. 0.16 123 North Orange County Riverside Co. 0.21 162 Metropolitan Riverside Co. San Bernardino Co. 0.26 200 Cent San Bernardino Mtn
Mojave Desert/S alton Sea Area Basins Los Angeles Co. 0.14 108 Antelope Valley Riverside Co. 0.16 123 Coachella Valley

The number of days exceeding the federal standard varied widely by area ( Figure 2

- 4 ). Areas along the immediate coast did not exceed the federal st andard, due in large part to the prevailing sea breeze which transports polluted air inland before high ozone concentrations can be reached. In addition, some inland areas which are remote fromFINAL 1997 AQMP

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- 8

urban areas of the Basin did not exceed the standard. The st andard was exceeded most frequently in the inland valleys extending from East San Fernando Valley through the San Gabriel Valley into the Riverside

- San Bernardino area, and in the adjacent mountains. The East San Gabriel Valley recorded the greatest numbe r of exceedances of the federal standard (73 days), health advisory level (48 days) and Stage I episode level (9 days). The greatest number of state standard exceedances (123 days) was recorded in the East San Bernardino Valley area.

FIGURE 2

- 4

Ozone

- 1 995 Number of Days Exceeding the Federal Standard (1

- hour average ozone > 0.12 ppm)



### Carbon Monoxide (CO) Specific Information

Health Effects

A consistent association between increasing ambient CO levels and excess admissions for heart diseases, such as c ongestive heart failure, is observed in many cities across the United States. Individuals with a deficient blood supply to the heart are more susceptible to the adverse effects of CO exposure. The effects observed include earlier onset ofChapter 2 Air Quality and Health Effects

2

- 9 chest pain with exercise, and electrocardiograph changes indicative of worsening oxygen supply to the heart.

Inhaled CO has no direct toxic effect on the lungs, but exerts its effect on tissues by interfering with oxygen transport by competing with oxygen to combine with hemoglobin present in the blood to form carboxyhemoglobin (COHb). Hence, conditions with an increased demand for oxygen supply can be adversely affected by exposure to CO. Examples include fetal development, chronic hypoxemia (oxygen deficiency) as seen in high altitudes, anemia, and diseases involving heart and blood vessels.

Reduction in birth weight and impaired neurobehavioral development have been observed in animals chronically exposed to CO resulting in COHb levels similar to those observed in smo kers.

Air Quality

Carbon monoxide concentrations were measured at 22 locations in the Basin and neighboring MDAB/SSAB areas in 1995. Table 2

- 3 shows the 1995 maximum 8

- hour average concentrations of carbon monoxide by air basin and county. The highest

co ncentration recorded in the Basin (13.86 ppm in South Central Los Angeles County) was 146 percent of the federal standard and 152 percent of the state standard. Maximum carbon monoxide concentrations in Orange, Riverside, and San Bernardino County areas

o f the Basin did not exceed the standards.

Maxima for the MDAB/SSAB were much lower. Carbon monoxide levels in both Los Angeles and Riverside County MDAB/SSAB areas remained well below the federal standard.

Figure 2

- 5 shows the number of days exceeding the federal standard in 1995. Exceedances were limited to the areas of Los Angeles County where vehicular traffic is most dense, with the maximum number of exceedances (13 days exceeding the federal standard and 15 days exceeding the state standard) recorded in the South Central Los Angeles County area.

TABLE 2

- 3 1995 Maximum Carbon Monoxide Concentrations by Basin and County

Basin/County Maximum

8

- Hr Avg. ppm Percent of

Federal Standard Area

South Coast Air BasinFINAL 1997 AQMP

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- 10

Los Angeles 13.86 146 South Central L.A. Co. Orange 8.00 84 Central Orange Co. Riverside 6.50 68 Metropolitan Riverside Co. San Bernardino 6.25 66 Cent San Bernardino V.
Mojave Desert/Salton Sea Area Basins Los Angeles 4.87 51 Antelope Valley Riverside 1.50 16 Coachella Valley

FIGURE 2

- 5

Carbon Monoxide

- 1995 Number of Days Exceeding the Federal Standard (8

- hour average CO  9.5 ppm)



### Particulate Matter (PM 10 

### ) Specific Information

Health Effects

A consistent correlation between elevated ambient PM 10 levels and an increase in mortality rates, respiratory infections, number and severity of asthma attacks and the number of hospital admissions has been observed in different parts of the United States and various areas around the world. Although the concentrations and/or combinations ofChapter 2 Air Quality and Health Effects

2

- 11 pol lutants are significantly different in these studies, most of the PM 10 levels recorded in these studies are lower than those observed in the South Coast Air Basin.

In recent years, some studies have reported an association between long

- term exposure to air pollution dominated by fine particles and increased mortality, reduction in life

- span, and the possibility of an increased incidence of cancer.FINAL 1997 AQMP

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- 12

Daily fluctuations in PM 10 levels have also been related to hospital admissions for acute respiratory conditio ns in children, to school and kindergarten absences, to a decrease in respiratory lung volumes in normal children and to increased medication use in children and adults with asthma.

The elderly, people with pre

- existing respiratory and/or cardiovascular di sease and children appear to be susceptible to the effects of PM 10 . There is a growing consensus among the scientific community that the fine fraction of PM 10 is relatively more toxic than the coarse fraction and is responsible for the majority of effects observed.

Air Quality

PM 10 concentrations were monitored at 21 locations by the South Coast Air Quality Management District in 1995. Maximum 24

- hour and annual average concentrations are shown in Tables 2

- 4 and 2

- 5 . The maximum 24

- hour PM 10 concentratio n recorded in the Basin (219 μg/m 3 in the Metropolitan Riverside County area) was 145 percent of the federal standard and 429 percent of the state standard. The maximum was associated with high winds, but other exceedances of the federal standard not asso ciated with high winds were recorded. Maximum concentrations in all four of the Basin counties exceeded the federal 24

- hour standard. The maximum annual average PM 10 (69 μg/m 3 in Metropolitan Riverside County) was 138 percent of the federal annual standa rd. The federal annual standard was exceeded in Riverside and San Bernardino Counties but not in Los Angeles or Orange Counties. The much more stringent state annual standard was exceeded in all areas of the Basin.

In 1995, both annual and 24

- hour maxim um concentrations of PM 10 in the Los Angeles County portion of the MDAB were below the federal standards. However in the Riverside County area of the SSAB, both standards were exceeded. The maximum 24

- hour PM 10 concentration (199 μg/m 3 in the Coachella V alley) was 132 percent of the federal 24

- hour standard, and was associated with high winds in the desert areas. The maximum annual average PM 10 concentration (52.0 μg/m 3 in the Coachella Valley) was 104 percent of the federal annual standard. It should b e noted that the exclusion of the high wind event day reduces the annual average to 49.5 μg/m 3 , or 99 percent of the standard.Chapter 2 Air Quality and Health Effects

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- 13 TABLE 2

- 4

1995 Maximum 24

- hour Average PM 10 Concentrations by Basin and County

Basin/County Maximum

24

- Hr Avg.  g/m 3 Percent of

Federal Standard Area

South Coast Air Basin Los Angeles 177 104 Pomona/Walnut Valley Orange 172 114 Central Orange Co. Riverside 219 145 Metropolitan Riverside Co. San Bernardino 178 118 Cent San Bernardino V.
Mojave Desert/Salton Sea Area Basins Los Angeles 61 40 Antelope Valley Riverside 199 132 Coachella Valley Riverside, corrected* 133* 88* Coachella Valley

*Adjusted for one high

- wind natural event day.

TABLE 2

- 5 1995 Maximum Annual Average PM 10 Concentrations by Basin and County

Basin/Co unty Annual

Average  g/m 3 Percent of

Federal Standard Area

South Coast Air Basin Los Angeles 49.1 98 East San Gabriel Valley Orange 43.5 86 Central Orange Co. Riverside 69.0 138 Metropolitan Riverside Co. San Bernardino 61.0 122 Cent. San Bernardin o V.
Mojave Desert/Salton Sea Area Basins Los Angeles 25.6 52 Antelope Valley Riverside 52.0 104 Coachella Valley Riverside, corrected* 49.5* 99* Coachella Valley

*Adjusted for one high

- wind natural event day.

Figure 2

- 6 shows the percent of days ex ceeding the federal 24

- hour average PM 10 standard in 1995. (PM 10 is normally sampled every sixth day, and for this reason is reported in terms of the percent of days sampled which exceeded the standard.) The federal standard was exceeded in parts of all four Basin counties, with the greatestFINAL 1997 AQMP

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- 14

percent of days exceeding recorded in the vicinity of the Metropolitan Riverside County area. No exceedances were recorded in the coastal Los Angeles and Orange County areas, or in the inland areas of the Basin most removed from urban areas. However, still further inland (east of the area on the map) the SSAB’s Coachella Valley area did record an exceedance of the standard, which was associated with high winds. The more stringent state 24

- hour PM 10 standard was exce eded at all District monitoring locations in the Basin and MDAB/SSAB.

FIGURE 2

- 6

PM 10 - 1995 Percent of Days Exceeding the Federal Standard (24

- hour average PM 10 > 150 μg/m 3 )

Figure 2

- 7 shows the 1995 annual average PM 10 concentration. The federal stand ard was exceeded in the areas of Riverside and San Bernardino Counties in and around the Metropolitan Riverside County area. Most areas of the Basin did not exceed the federal annual PM 10 standard. However the more stringent state annual PM 10 standard wa s exceeded throughout most of the Basin and in part of the SSAB (Riverside County’s Coachella Valley area).Chapter 2 Air Quality and Health Effects

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- 15 FIGURE 2

- 7

PM 10 - 1995 Annual Average Concentration Compared to Federal Standard (Federal standard = 50 μg/m 3 , annual arithmetic mean)



### Nitrogen Dio xide (NO 2 

### ) Specific Information

Health Effects

Population

- based studies suggest that an increase in acute respiratory illness, including infections and respiratory symptoms in children (not infants), is associated with long

term exposures to NO 2 at levels found in homes with gas stoves, which are higher than ambient levels found in Southern California. Increase in resistance to air flow and airway contraction without any effect on lung volumes (breathing capacity) is observed after short

- term exposure to N O 2 in healthy subjects. Larger decreases in lung volumes are observed in individuals with asthma and/or chronic obstructive pulmonary disease (e.g., chronic bronchitis, emphysema) than in healthy individuals, following exposure to lower levels of NO 2 , ind icating the greater susceptibility of these sub

- groups.
In animals, exposure to levels of NO 2 considerably higher than ambient concentrations results in increased susceptibility to infections, possibly due to the observed changes in cells involved in maint aining immune functions. The severity of lung tissue damageFINAL 1997 AQMP

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- 16

associated with high levels of ozone exposure increases when animals are exposed to a combination of ozone and NO 2 . Air Quality

In 1995, nitrogen dioxide concentrations were monitored at 24 locat ions. No area of the Basin, MDAB or SSAB exceeded the federal or state standards for nitrogen dioxide. Maximum annual average concentrations for 1995 are shown in Table 2

- 6. The highest annual average concentrations recorded in the Basin (0.0464 ppm in the East San Gabriel Valley and Northwest San Bernardino Valley areas) were 87 percent of the federal standard, while the highest concentration recorded in the MDAB/SSAB was 42 percent of the standard. The Basin has not exceeded the federal standard for n itrogen dioxide since 1991, when the Los Angeles County portion of the Basin recorded the last exceedance of the standard in any U.S. county.

The state standard was not exceeded at any District monitoring location in 1995. The highest 1

- hour average conce ntration recorded (0.24 ppm in Central Los Angeles) was 92 percent of the state standard.

TABLE 2

- 6 1995 Maximum Nitrogen Dioxide Concentrations by Basin and County

Basin/County Maximum

Annual Avg. ppm Percent of

Federal Standard Area

South Coast Air Basi n Los Angeles 0.0464 87 East San Gabriel Valley Orange 0.0391 73 North Orange Co. Riverside 0.0306 57 Metropolitan Riverside Co. San Bernardino 0.0464 87 Northwest San Bernardino V.
Mojave Desert/Salton Sea Area Basins Los Angeles 0.0193 36 Ante lope Valley Riverside 0.0223 42 Coachella Valley



### Sulfur Dioxide (SO 2 

### ) Specific Information

Health Effects

Even an exposure of a few minutes to low levels of SO 2 can result in airway constriction in some asthmatics. All asthmatics are sensitive to the ef fects of SO 2 . In asthmatics, increase in resistance to air flow, as well as reduction in breathing capacity leading toChapter 2 Air Quality and Health Effects

2

- 17 severe breathing difficulties, are observed after acute exposure to SO 2 . In contrast, healthy individuals do not exhibit similar acute responses even after exposure to higher concentrations of SO 2 . Animal studies suggest that despite SO 2 being a respiratory irritant, it does not cause substantial acute or chronic toxicity at ambient concentrations. However, very high levels of exposure c an cause lung edema (fluid accumulation), lung tissue damage, and sloughing off of cells lining the respiratory tract.

Some population

- based studies indicate that the mortality and morbidity effects associated with fine particles show a similar association with ambient SO 2 levels. In these studies, efforts to separate the effects of SO 2 from fine particles have not been successful. It is not clear whether the two pollutants act synergistically or whether one pollutant alone is the predominant factor.

Air Quality

No exceedances of federal or state standards for sulfur dioxide occurred in 1995 at any of the nine District locations monitored. Though sulfur dioxide concentrations remain well below the standards, sulfur dioxide is a precursor to sulfate, which is a component of PM 10 . Standards for both sulfate and PM 10 were exceeded in 1995.

Maximum concentrations of sulfur dioxide for 1995 are shown in Table 2

- 7 . The maximum 24

- hour average sulfur dioxide (0.018 ppm, recorded in South Coastal Los Angeles Cou nty) was 13 percent of the federal 24

- hour standard. The maximum annual average concentration (0.0030 ppm in the South Central Los Angeles County area) was 10 percent of the federal annual standard.

Sulfur dioxide was not measured at MDAB/SSAB sites in 19 95. Historical measurements showed concentrations to be well below standards and monitoring has been discontinued.

The more stringent state 1

- hour standard was last exceeded in 1990, due to a breakdown at a Basin refinery (the first such exceedance since 1984). In 1995, the maximum 1

- hour average sulfur dioxide concentration (0.14 ppm in the South Coastal Los Angeles County area) recorded was 54 percent of the state standard.FINAL 1997 AQMP

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- 18 TABLE 2

- 7 1995 Maximum Sulfur Dioxide Concentrations by Basin and County

Basin/ County Maximum

24

- hr Avg. ppm Percent of

Federal Standard Area

South Coast Air Basin Los Angeles 0.018 13 South Coastal L.A. Co. Orange 0.010 7 North Orange Co. Riverside 0.006 4 Metropolitan Riverside Co. San Bernardino 0.010 7 Central San Bernard ino V.
Mojave Desert/Salton Sea Area Basins Los Angeles N.D. Riverside N.D.

N.D. = No Data. Historical measurements indicate concentrations are below standard



### Sulfates (SO 4 = 

### ) Specific Information

Health Effects

Most of the health effects associa ted with fine particles and sulfur dioxide at ambient levels are also attributable to sulfates. Thus, both mortality and morbidity effects are observable with an increase in ambient sulfate concentrations. However, efforts to separate the effects of sulf ates from the effects of other pollutants, including ozone, have not been successful.

Clinical studies of asthmatics exposed to sulfuric acid suggest that adolescent asthmatics are probably a subgroup susceptible to acid aerosol exposure. Animal studies s uggest that acidic particles such as sulfuric acid aerosol and ammonium bisulfate are probably more toxic than non

- acidic particles like ammonium sulfate. Whether the effects are attributable to acidity or to particles remains unresolved. However, the se verity of effects observed appears to be greater in population studies from the eastern United States and Canada, where sulfate concentrations are higher, than in the western United States.

Air Quality

In 1995, the state sulfate standard was exceeded in on e area of the Basin (the Metropolitan Riverside County area) on 2 percent of days sampled. The maximum concentration recorded (26.3 μg/m 3 ) was 105 percent of the state standard. MaximumChapter 2 Air Quality and Health Effects

2

- 19 concentrations by air basin and county are shown in Table 2

- 8 . No e xceedances were recorded in Los Angeles, Orange, or San Bernardino Counties in 1995.

No sulfate data were obtained at MDAB/SSAB stations in 1995. Historical sulfate data showed concentrations in the MDAB/SSAB areas to be well below the standard, and

measu rements have been discontinued.

TABLE 2

- 8 1995 Maximum Sulfate Concentrations by Basin and County

Basin/County Maximum

24

- hr Avg. μg/m 3 Percent of

Federal Standard Area

South Coast Air Basin Los Angeles 20.4 82 South Coastal L.A. Co. Orange 12.8 51 C entral Orange Co. Riverside 26.3 105 Metropolitan Riverside Co. San Bernardino 13.4 54 Central San Bernardino V.
Mojave Desert/Salton Sea Area Basins Los Angeles N.D. Riverside N.D.

N.D. = No Data. Historical measurements indicate concentratio ns are below standard



### Lead (Pb) Specific Information

Health Effects

Fetuses, infants, and children are more sensitive than others to the adverse effects of lead exposure. Exposure to low levels of lead can adversely affect the development and function of the central nervous system, leading to learning disorders, distractibility, inability to follow simple commands, and lower intelligence quotient. In adults, increased lead levels are associated with increased blood pressure.

Lead poisoning can cause anem ia, lethargy, seizures and death. It appears that there are no direct effects of lead on the respiratory system. Lead can be stored in the bone from early

- age environmental exposure, and elevated blood lead levels can occur due to breakdown of bone tiss ue during pregnancy, hyperthyroidism (increased secretion of hormones from the thyroid gland) and osteoporosis (breakdown of bony tissue). Fetuses and breast

- fed babies can be exposed to higher levels of lead because of previous environmental lead exposur e of their mothers.FINAL 1997 AQMP

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- 20

Air Quality The federal and state standards for lead were not exceeded in any area of the District in 1995. There have been no violations of the standards at the District’s regular air monitoring stations since 1982 as a result of remo val of lead from gasolines. However, special monitoring stations immediately adjacent to stationary sources of lead have recorded exceedances of the standards in very localized areas of the Basin as recently as 1991 for the federal standard and 1994 for t he state standard. Table 2

- 9 shows the maximum concentrations recorded in 1995.

The maximum quarterly average lead concentration (0.06 μg/m 3 at several Los Angeles County sites) recorded at District air monitoring stations was 4 percent of the federal

st andard. The highest quarterly average lead concentration (0.60 μg/m 3 in Southeast Los Angeles County) measured at special monitoring locations immediately adjacent to stationary sources of lead was 40 percent of the federal standard.

The maximum monthly average lead concentration at the regular monitoring stations (.07 μg/m 3 at several Los Angeles County locations) was 5 percent of the state standard, and the maximum at the special monitoring sites immediately adjacent to sources (0.62 μg/m 3
in Southeast Los Angeles County) was 41 percent of the standard.

TABLE 2

- 9

1995 Maximum Lead Concentrations * by Basin and County
Basin/County Maximum

Quarterly Average.  g/m 3 Percent of

Federal Standard Area

South Coast Air Basin Los Angeles 0.06 4 Multiple Site s Orange 0.04 3 Central Orange Co. Riverside 0.04 3 Metropolitan Riverside Co. San Bernardino 0.04 3 Central San Bernardino V.
Mojave Desert/Salton Sea Area Basins Los Angeles N.D. Riverside N.D.

N.D. = No Data. Historical measurements indica te concentrations are below standard

* Higher concentrations of lead were recorded at special monitoring stations in the immediate vicinity of stationary sources of lead. The maximum concentration (quarterly average lead concentration 0.60 μg/m 3 in the Southeast Los Angeles County area) at the special monitoring sites was 40 percent of the federal standard.Chapter 2 Air Quality and Health Effects

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### Visibility Specific Information

Air pollution induced visibility degradation in the Basin is due primarily to particulate matter. On some days, the presence of water droplets may contribute significantly to visibility reduction. Days for which this is true are removed by excluding days on which the relative humidity was greater than 70 percent from consideration when determining compliance with the standard

In 1995, visual range data were collected at two locations in the Basin. Both sites exceeded the state standard by a significant margin. The standard was exceeded on a maximum of 35 percent of days in the only area (East San Gabriel Valley area of Los Angeles County) for which complete data were available.



### Summary

In 1995, the Basin continued to exceed federal and state standards for ozone, PM 10 , and carbon monoxide, and the state standards for sulfate and visibility. The MDAB/SSAB areas continued to exceed standards for ozone and PM 10 . However for PM 10 , the remov al of one high wind natural event in the Coachella Valley results in MDAB/SSAB meeting the federal PM 10 standards, but not the state PM 10 standards.

The Basin exceeded one or more federal standards on nearly one third of the days of the year. Maximum conc entrations of PM 10 and carbon monoxide were nearly one and one

half times the federal standards, and the maximum ozone concentration was twice the federal standard.