Air Toxics One-Year Report: Oil Companies Used Millions of Pounds of 

Air-Polluting Chemicals in Los Angeles Basin Neighborhoods

An Analysis from the Center for Biological Diversity, Physicians for Social 

Responsibility – Los Angeles, Communities for a Better Environment, and the 

Center on Race, Poverty and the Environment

June 2014

One year after the South Coast Air Quality Management District (SCAQMD) began 

requiring the oil and gas industry to report the use of chemicals in certain well 

operations in the South Coast Air Basin, records show that oil companies have used

44 different air toxic chemicals more than 5,000 times in Los Angeles and Orange 

counties in the past 12 months.

The known air toxics most frequently used by oil companies in the Los Angeles air basin 

include crystalline silica, hydrofluoric acid, and formaldehyde. Air toxics are those 

chemicals considered to be among the most dangerous air pollutants because they 

have been proven to cause significant health harms, illness, and death. Formaldehyde, 

for example, harms the eyes and respiratory system and is classified as a cancercausing substance by the International Agency for Research on Cancer and the 

California Air Resources Board.

The oil industry has reported the use of more than 45 million pounds — or 22,500 tons 

— of air toxics in 477 hydraulic fracturing (“fracking”), acidizing and gravel packing 

operations in Los Angeles and Orange counties since mandatory reporting began in 

June of 2013. Oil companies have also claimed “trade secret” protection 5,050 times to 

conceal information on air toxics and other chemicals used. The data also shows that 

more than half of the fracking, acidizing, and gravel packing events reported by the oil 

industry have occurred within 1,500 feet of a home, school, or medical facility. 

While the data collection’s scope is limited, the information does provide insight into the 

oil and gas industry’s previously hidden reliance on the use of air toxics in Los Angeles 

and Orange counties. Further, the data highlights the danger to which communities are 

exposed as these chemicals are transported and used and focuses attention on the 

critical need for policies that address the substantial harm that can be caused by the 

routine and accidental releases of these toxic air pollutants. 

Finally, the data shows the oil industry’s common use of “trade secret” claims to conceal

the true scope and nature of the dangers to which their operations expose the people of 

Los Angeles and Orange counties. 
L.A. Basin Oil Industry Air Toxics Report Page 2

BACKGROUND

In April of 2013, the South Coast Air Quality Management District (SCAQMD) adopted 

Rule 1148.2, establishing the state’s first notification and reporting requirements for 

selected enhanced oil and gas recovery activities.1

Starting June 4, 2013, SCAQMD required oil and gas well operators to submit reports 

(“Event Reports”) that disclose where and when they plan to use the oil and gas

recovery techniques of acidization, gravel packing, and fracking. 

The rule also requires operators to disclose the chemicals used in these operations in a 

publicly available chemical report within 60 days of completing the activity (“Chemical 

Reports”). In July 2013, operators started disclosing some, but not all, of the chemicals 

being used. As required by the rule, SCAQMD has made this data available online. 

FINDINGS

Based on a review of one year’s worth of reports, SCAQMD data shows that oil and gas 

production employs an alarming amount of chemicals in communities in the South 

Coast Air Basin.2 Many of these chemicals are known “air toxics” — chemicals that can 

cause serious health effects in people exposed to them. 

Since reporting began, there have been 477 instances of fracking, acidizing, and gravel 

packing in the region. In total, at least 44 different air toxics have been used 5,068

times. The most commonly used air toxic, crystalline silica, was used more than 1,500

times. 

Hundreds of Well Stimulation Events

Well stimulation is any type of activity used to enhance the flow of hydrocarbons. The 

particular well stimulation techniques that are the focus of this reporting requirement

have been used hundreds of times in Los Angeles and Orange counties over the past 

year. The data shows that more than once per day, on average, chemicals are being 

injected into an oil well in Los Angeles or Orange County. 

Well Stimulation Reported Occurrences

Acidizing 314

Gravel Packing 149

Fracking 14

Total3 477

 1 SCAQMD Rules and Regulations, Rule 1148.2, available at http://www.aqmd.gov/rules/reg/reg11/r1148-2.pdf 2 The South Coast Air Basin covers all of Orange County and the urban portions of Los Angeles, Riverside, and San 

Bernardino Counties. The data shows that all of the activity reported occurred in Los Angeles and Orange Counties.

3 The number is the difference of the number of “Original” reports less the number of “Cancellation” reports. 

“Revision” reports were not counted as they typically would not significantly increase or decrease the total 

number of well stimulation events. 
L.A. Basin Oil Industry Air Toxics Report Page 3

Acidizing: Acidizing is a process in which a combination of hydrochloric acid and other 

acids are mixed with brine and other chemicals and injected underground to either clean 

out a well or to dissolve oil bearing rock to enhance production of oil and gas. Once the 

acid, chemical, and water mixture has been pumped into the well or formation, oil flows 

to the well more freely. Since event reporting began in early June 2013, there have 

been approximately 314 acidizing events reported in Los Angeles and Orange 

counties.4

This number is likely less than the actual number of acidizing events that have 

occurred.5 Several reports disclose that the operator used acid for an “acid wash” or 

“acid perforation,” but failed to check “Y” under the acidizing query on the reporting form. 

Thus, even though large amounts of acid, chemicals, and water have been pumped into 

the ground, it is not counted on aggregate data searches because the operator did not 

check the “acidizing” box on the form. This analysis did not attempt to correct for this 

discrepancy and, therefore, may underreport the actual number of acidizing events. 

Gravel Packing: In gravel packing, gravel is injected with a chemical mixture and 

placed near the wellbore to form filters that help prevent the buildup of sand inside the 

well. Minimizing sand buildup increases the flow of oil to the surface. Since June 2013, 

there have been approximately 149 gravel packing events reported in Los Angeles and 

Orange counties. Again, some reports indicate that gravel packing has occurred, but the 

operator did not categorize it as gravel packing on the report. For example, an operator 

reported “Not Stim[ulation] – Gravel Pack,” but left the gravel packing box unchecked. 

Thus, like acidizing, even though gravel packing has occurred, it is not always included 

in aggregate data searches because the operator did not check the gravel packing box 

on the form. Consequently, the actual number of gravel packing incidents may be 

higher. 

Hydraulic Fracturing: Also known as “fracking,” hydraulic fracturing is a recovery 

method in which large amounts of water, sand (typically), and chemicals are injected 

under extremely high pressures into a rock formation to create fractures in the oilbearing rock to enhance oil flow from the well. Since June 2013, there have been 

approximately 14 fracking events reported in Los Angeles and Orange counties. 

Most Common Air Toxics

A review of the data from June 4, 2013, through June 3, 2014, shows that at least 44 

different chemicals reported as being air toxics were used by operators. These 

chemicals were used in at least 5,068 instances. More than 45 million pounds — or 

22,500 tons — of these air toxics were used. 

 4 This includes reports of acidizing, acid matrix, acid maintenance, and acid fracturing. 5 Rule 1148.2 defines “Acidizing” as “a treatment of the wellbore or reservoir formation with an acid to either 

clean out scale, damage, or other debris in the well, or react with the soluble substances in the formation to 

improve permeability and enhance production of oil and gas.” Rule 1148.2(c)(1).
L.A. Basin Oil Industry Air Toxics Report Page 4

The 12 most commonly used air toxics are shown in the chart below:

The 12 Most Commonly Used Air Toxins in Unconventional Oil 

Production in the L.A. Basin6

Rank Chemical Number 

of 

Instances 

Used7

Total 

amount by 

mass (lbs.)

Known Health Effects8

1 Crystalline 

Silica9

1590 25,497,493 Harmful to skin, eyes, and sensory 

organs, respiratory system, immune 

system and kidneys; mutagen.

2 Methanol 810 166,751 Harmful to skin, eyes, and sensory 

organs, respiratory system, 

gastrointestinal system and liver, 

brain and nervous system, immune 

system, kidneys, reproductive and 

cardiovascular system; mutagen, 

developmental inhibitor and 

endocrine disruptor.

3 Hydrochloric 

Acid

498 10,897,302 Harmful to skin, eyes, and sensory 

organs, respiratory system, 

gastrointestinal system and liver, 

immune system, cardiovascular 

system and blood.

4 Formaldehyde 232 32,519 Harmful to skin, eyes, and sensory 

organs, respiratory system, 

gastrointestinal system and liver, 

brain and nervous system, immune 

system, kidneys, reproductive 

system and cardiovascular system; 

mutagen, developmental inhibitor.

5 Amorphous 

Silica10

215 750,300 Harmful to skin, eyes and other 

sensory organs, respiratory system, 

 6 Records from July 1, 2013 through May 25, 2014

7 In some cases, the same chemical ingredient was listed as being used multiple times in the same chemical report 

for different purposes. In such cases, each use is counted separately. 

8 Unless otherwise noted, health effects are documented by TEDX Endocrine Disruptor Exchange. Spreadsheet of 

health effects listed by chemical is available at http://endocrinedisruption.org/chemicals-in-natural-gasoperations/chemicals-and-health. 9 Includes reported uses of crystalline silica; crystalline silica (quartz); crystalline silica, quartz (SIO2); crystalline 

silica, quartz; crystalline silica (SI [sic]; quartz (SIO2); silica, crystalline, quartz; crystalline silica tridymite; tridymite; 

tridymite (SIO2), crystalline silica cristobalite, cristobalite (SIO2).

10 Includes reports listing amorphous silica, silica, silica fumed, amorphous silica fumed, and fumed silica. 
L.A. Basin Oil Industry Air Toxics Report Page 5

gastrointestinal system and liver; 

linked to lung cancer.

6 Hydrofluoric 

Acid

204 5,454,496 Harmful to skin, eyes, and sensory 

organs, respiratory system, 

gastrointestinal system and liver, 

brain and nervous system, immune 

system, kidneys, reproductive 

system and cardiovascular system; 

mutagen, developmental inhibitor.

7 Naphthalene 185 25,014 Harmful to skin, eyes, and sensory 

organs, respiratory system, 

gastrointestinal system and liver, 

brain and nervous system, immune 

system, kidneys, cardiovascular 

system; mutagen, endocrine 

disruptor, developmental inhibitor.

8 2-Butoxy 

Ethanol11

177 69,988 Harmful to skin, eyes and other 

sensory organs, respiratory system, 

gastrointestinal system and liver, 

brain and nervous system, immune 

system, kidneys, reproductive 

system and cardiovascular system; 

mutagen, developmental inhibitor 

and endocrine disruptor; linked to 

liver cancer. Also linked to adrenal 

tumors.12

9 Alumina / 

Aluminum 

Oxide

145 761,889 Harmful to skin, eyes and other 

sensory organs, respiratory system, 

and brain and nervous systems. 

10 Xylene 116 97,178 Harmful to skin, eyes and other 

sensory organs, respiratory system, 

gastrointestinal system and liver, 

brain and nervous system, immune 

system, kidneys, reproductive and 

cardiovascular system; 

developmental inhibitor and 

endocrine disruptor.

11 Glutaral/ 

Pentanedial

116 67,298 Harmful to skin, eyes, and sensory 

organs, respiratory system, 

gastrointestinal system and liver, 

 11 Includes reports listing 2-butoxyethanol and ethylene glycol monobutane ether 12 U.S. EPA Integrated Risk Information System, Ethylene glycol monobutyl ether (EGBE)(2-Butoxyethanol) (CASRN 

111-76-2), available at http://www.epa.gov/iris/subst/0500.htm; See also Abraham Lustgarten, ProPublica, Buried 

Secrets: Is Natural Gas Drilling Endangering US Water Supplies? 
L.A. Basin Oil Industry Air Toxics Report Page 6

brain and nervous system, immune 

system, kidneys, reproductive and 

cardiovascular system; mutagen, 

developmental inhibitor and 

endocrine disruptor.

12 Ethylbenzene 111 81,934 Harmful to skin, eyes, and sensory 

organs, respiratory system, 

gastrointestinal system and liver, 

brain and nervous system, kidneys, 

reproductive system and 

cardiovascular system; suspected 

carcinogen, mutagen, endocrine 

disruptor, developmental inhibitor.

Chemicals Used Close to Schools, Hospitals and Homes

SCAQMD data shows that roughly 265 reported well stimulation events occurred at 

sites within 1,500 feet of at least one hospital, preschool, or residence — and some 

were as close as 12 feet. Many wells are close to several facilities housing people 

especially vulnerable to toxic chemicals. For example, Freeport-McMoRan Oil and Gas 

Company conducted three acidizing events at its Jefferson production site, a cluster of 

wells located in a densely populated part of Los Angeles. Those chemical-intensive 

activities took place just 85 feet from homes, 145 feet from a church, and 770 feet from 

an elementary school. Use of industrial chemicals near children and the elderly is 

especially concerning because chemicals may have relatively severe health effects in 

these vulnerable populations compared to the general adult population. Medical and 

health professionals warn of substantial and detrimental health risks for surrounding 

communities. 

Voices from the Medical Community

James Dahlgren, M.D.

“Children, the elderly, and people who are already sick are especially at risk from 

exposures to air toxics. Data collected over the years strongly supports the need for 

special attention to be paid to these populations because they tend to have reactions to 

chemicals at lower levels than the general adult population.” 
L.A. Basin Oil Industry Air Toxics Report Page 7

Fig. 1: The Jefferson wells in Los Angeles and their proximity to surrounding receptors.

In another example, Brea Canon Oil Company acidized its Joughlin 3-D well located in 

the middle of a residential neighborhood in Harbor City. The nearest home was only 50 

feet from the well where dozens of toxic chemicals were used to acidize the well. 

Figure 2: Joughlin 3-D well and its proximity to residences in Harbor City, California

Jefferson Wells

770 ft. from 

elementary school 85 ft. from 

residences

145 ft from 

Church

Joughlin well

50 ft. from nearest 

residences
L.A. Basin Oil Industry Air Toxics Report Page 8

“Trade Secret” Claims Conceal Key Information

Oil industry reporting may significantly understate the frequency and volume of chemical 

use because operators have withheld chemical information from their reports in 5,050

instances. 

The full extent of the risks of oil recovery techniques is still unknown, in part because oil 

companies have kept the identity of certain chemicals hidden from the public based on 

claims that the list of chemicals used in 

certain “products” is a trade secret. Instead of 

disclosing the chemicals used, the company 

merely submits a vague description, which 

SCAQMD substitutes for the real chemical 

information when the reports are posted 

online. These descriptions are often so vague 

that they do not provide the public with useful 

information about what chemicals were used. 

For example, some “trade secret” chemicals 

are described as a “lubricant,” “surfactant,” or

simply, “mixture.” 

Trade secret claims can be used by 

companies to hide their proprietary 

information, but such protections do not apply 

to chemical identities and concentrations related to well stimulation. California state law 

clearly states: 

Notwithstanding any other law or regulation, none of the following shall be 

protected as a trade secret: [t]he identities of the chemical constituents of 

additives, including [chemical abstract service] identification numbers.13

Thus, none of the 5,050 claims for a trade secret is valid under state law. Despite the 

clear and explicit statute, operators continue to withhold chemical information by 

submitting claims of trade secrecy for a large number of chemicals, leaving the public 

with no knowledge of what chemicals are being used or in what quantities. Despite 

multiple requests14 to SCAQMD asking for public disclosure of all chemical identities, 

SCAQMD has so far offered no information or explanation as to why the information 

remains withheld from the public. 

 13 California Public Resources Code § 3160(j)(2). 14 The Center for Biological Diversity and Physicians for Social Responsibility – Los Angeles first sent a request 

under the California Public Records Act to SCAQMD on October 2, 2013. The organizations asked for chemical 

information reported under Rule 1148.2, including chemicals claimed to be trade secrets.

Chemical Profiles

Formaldehyde: A colorless, strongsmelling gas, formaldehyde is used as a 

corrosion inhibitor and dispersant during 

certain oil extraction activities. 

Formaldehyde is a known carcinogen 

known to increase the risk of lung 

cancer and leukemia. Acute exposure 

may result in headache, nausea, 

vomiting, pneumonia, dyspnoea, 

respiratory depression, pulmonary 

oedema, and burning of the nose, eyes, 

and throat.
L.A. Basin Oil Industry Air Toxics Report Page 9

In addition, many of the trade-secret protected 

chemicals are marked as an air toxic. Of the 

5,050 instances in which an operator withheld 

the identity of a chemical, 1,037 are marked as 

being an air toxic. Another 663 trade secret 

claims provide no indication of whether it is an 

air toxic or not. This means that as many as 

one third of that group of chemicals could be 

additional, undisclosed air toxics being used in 

communities. 

Furthermore, the air toxic designation of 

withheld chemicals is not viewable when 

individual reports are viewed on the SCAQMD 

website. Thus, a chemical under a trade secret 

claim may show a “Y,” indicating an air toxic, 

when downloaded from the site with other well 

information, but when the individual report is 

viewed on the SCAQMD website, the box 

indicating the presence of an air toxic next to 

the same trade secret claim is left unchecked. This means a person looking up a 

particular well stimulation report online will not know whether any of the trade secret 

claims are hiding the use of an air toxic. This seems to be a limitation in SCAQMD’s 

online reporting interface.

Even More Chemicals Are Used In Other Stages of Oil and Gas Development

It should be noted that SCAQMD’s data captures only those chemicals used during well 

stimulation, not those used during other stages of development, such as site 

construction, drilling, well completion, conventional extraction, transportation, 

processing and refining, and end-use combustion. While SCAQMD has not required 

reporting for these chemicals, many studies show significant public health and safety 

concerns associated with oil and gas activity as a whole. 

For example, independent air quality sampling from Colorado showed that there was a 

spike of harmful air emissions during the initial drilling phase of a well. Mixtures known 

as “drilling muds,” which contain a number of chemicals, are used to facilitate the drilling 

process. The emitted air toxics included volatile organic compounds and polycyclic 

aromatic hydrocarbons.15 The study found that harmful chemicals were emitted 

throughout the process. Air sampling detected many chemicals known to have harmful 

human health effects, including acetaldehyde, benzene, formaldehyde, isoprene, 

naphthalene, and many more.16

 15 Theo Colborn et al., “An Exploratory Study of Air Quality near Natural Gas Operations,” Human and Ecological 

Risk Assessment: An International Journal (November 26, 2012). 

16 Colborn, pp. 29-32, Table 4. 

Chemical Profiles

Hydrofluoric Acid (hydrogen fluoride): 

Commonly used in acidizing to help 

dissolve materials inside a well or the 

underground shale formation, 

hydrofluoric acid is extremely corrosive 

and can cause severe skin burns upon 

contact. The chemical can cause a 

variety of health effects (see table 

above) and even cause death through 

skin exposure or inhalation. Releases of 

this chemical causes extremely 

dangerous clouds to form and drift along 

the ground without dispersing. Because 

of its highly dangerous properties, the 

SCAQMD adopted a rule to phase out 

its use in refineries. 
L.A. Basin Oil Industry Air Toxics Report Page 10

A separate study showed that toxic air emissions from well sites are likely to be far 

greater than official estimates. The study found that well sites were emitting benzene, a 

known carcinogen, at a rate seven times higher than U.S. EPA estimates.17 The study 

also found that methane, which can lead to increased levels of harmful ground-level 

ozone and smog, was emitted at rates three times higher than U.S. EPA estimates.18

Another chemical common in oil and gas operations is methylene chloride. Exposure to 

this highly volatile chemical can lead to damage to sensory organs, the liver, kidneys, 

respiratory system, immune system, cardiovascular system, brain and nervous system, 

gastrointestinal system, and endocrine system.19 It is also considered a potential 

carcinogen.20 Methylene chloride is thought to be widely used as a cleaning agent for 

equipment on oil and gas production sites. Because its use is separate from well 

stimulation fluid, operators do not report its use, yet studies have shown that it is 

prevalent in air samples taken close to oil and gas operations.21

Nearby Communities at Risk of Exposure

These air toxics, which can be emitted before, during, and after well stimulation, are 

endangering the health of nearby residents. In Los Angeles, the AllenCo oil facility has 

been cited for multiple air emission violations. The pollution has been linked to 

nosebleeds, headaches, breathing trouble, and nausea suffered by nearby residents, 

leading to hundreds of complaints to SCAQMD.22 After AllenCo was forced to halt 

operations, the Los Angeles Times revealed that reports of illnesses had diminished 

significantly. Whether or not well stimulation is used, oil and gas operations are 

responsible for emitting air toxics throughout the process. 

CONCLUSION

The data reported to SCAQMD, while incomplete in many ways, shows extensive and 

widespread use of harmful chemicals in the Los Angeles air basin. The pervasive and 

persistent use of these chemicals threatens to contaminate local air quality and put 

communities’ health and safety at risk. The reporting requirements have proven the 

need for immediate action to protect the public. 

 17 Gabrielle Petron et al., “A New Look at Methane and Non-Methane Hydrocarbon Emissions from Oil and

Natural Gas Operations in the Colorado Denver-Julesburg Basin,” Journal of Geophysical Research (2014), 

DOI: 10.1002/2013JD021272. 18 Id. 19 Colborn, pp. 29-32, Table 4. 20 U.S. Department of Health and Human Services, National Toxicology Program, “Report on Carcinogens, Twelfth 

Edition: Dichloromethane,” (2011). 

21 Colborn. at 10. 22 Louis Sahagun, “Chemical Odor, Kids’ Nosebleeds, Few Answers in South L.A. Neighborhood,” Los Angeles Times 

(September 21, 2013).