California’s Agriculture-Related Local Air Pollution Policy

doi:10.4236/jep.2013.48A1004

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Journal of Environmental Protection, 2013, 4, 24-27

http://dx.doi.org/10.4236/jep.2013.48A1004 Published Online August 2013 (http://www.scirp.org/journal/jep)

California’s Agriculture-Related Local Air Pollution Policy

C.-Y. Cynthia Lin

Faculty of Agricultural and Resource Economics, University of California at Davis, Davis, USA.

Email: [email protected]

Received May 8th, 2013; accepted June 13th, 2013; accepted July 25th, 2013

which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

ABSTRACT

Air pollution is a critical environmental issue for California, which has some of the nation’s most polluted air basins

and also the nation’s most stringent set of state and local air qu ality standards. This paper reviews my previous work in

Lin (2011), in which I examine the effects of agriculture-related lo cal regulations in California on air quality, as meas-

ured by the number of exceedances of the CO and NO2 standards, by exploiting the natural variation in policy among

the different air districts in California. Agricultural burning policies and penalty fees reduce the pollution from CO.

Other policies such as the prohibition on visible emission, fu gitiv e du st, particulate matter, nitrog en and th e redu ction of

animal matter are correlated with higher levels of CO. Regulations on orchard and citrus heaters have no significant

effect on the number of exceedances of the CO and NO2 standards.

Keywords: Air Quality; Air Pollution; Pollution Control; Agriculture

1. Introduction

Air pollution has been recognized as a significant envi-

ronmental problem in California since the early 20th

century. Between 1905 and 1912, regulations were en-

acted by the city council of Los Angeles to regulate

emissions [1]. As motor vehicle traffic increased, a new

type of smog was observed and described: the “Los An-

geles” or photochemical smog, as distinct from the

“London” smog that resulted from coal combustion. Arie

Haagen-Smit from Caltech characterized the chemistry

of this smog and identified ozone as the principal oxidant

in the early 1950’s. Meanwhile, the first air district in the

U.S. was created in Los Angeles in 1947, and was later

merged with other local districts in 1977 to form the

South Coast Air Quality Management District [1].

Negative effects of air pollution have been extensively

documented, and include impairment of human lung

function, degradation of materials, and injury to plants.

In addition to affecting human health, the high ambient

ozone levels found in Southern California and the San

Joaquin Valley also cau se yield reductions up to 30 % for

some crops [2].

In addition to having some of the nation’s most pol-

luted air basins, California also has the nation’s most

stringent set of state and local air quality standards. Al-

though regulation has led to improvements in air quality

[3], exceedances of air quality standards still take place.

For example, between 1990 and 1998, the San Joaquin

Valley Air Basin experienced an average of 97 days per

year above the eight-hour ozone standard, while the Sac-

ramento Valley Air Basin experienced an average of 30

days per year above the standard during the same time

period [4].

Farming and livestock operations are significant sources

of emissions in California, and bear the negative effects

of specific air pollutants as well. Agriculture-related air

pollution results from pri mary emissions from machinery

and vehicles employed in production, chemical com-

pounds used in the course of production, e.g. pesticides,

as well as emissions from the agricultural systems them-

selves. For example, agricultural livestock emit nitrogen

compounds such as oxides of nitrogen (NOx) and ammo-

nia. Vehicles used in agricultural production emit volatile

organic compounds (VOCs), NOx and carbon monoxide

(CO) [5]. These emissions may lead to the formation of

secondary air pollutants, such as ozone, that are deleteri-

ous to worker s as we ll as crops [6].

This paper reviews my previous work in [7], in which

I examine whether existing air pollution control policies,

particularly those targeted at agriculture, have succeeded

in improving air quality, as measured by the number of

exceedances of the CO and NO2 standards. The follow-

ing air pollution control policies are examined: policies

and regulations for agricultural burning, visible emis-

sions, fugitive dust, emission of particulate matter (PM)

California’s Agriculture-Related Local Air Pollution Policy 25

and PM precursors, emissions of nitrogen compounds,

orchard and citrus heaters that release black carbon, and

penalty fees.

My work in [7] builds upon the ex isting environ mental

economics literature on air quality, most notably the

econometric analysis of the impact of federal particulate

matter regulation on infant health conducted by [8] and

the study of the impact of air pollution on infant death in

California by [9], in several ways. First, [7] focuses on

the effects of regulation rather than on the effects of air

quality. The results therefore have direct implication s for

policy. Second, the econo metric methodology used in [7]

exploits the natural variation in policy among the differ-

ent air districts in California to identify the effects of

these policies. Third, [7] examines multiple policies, not

just one.

Results from the multivariable regressions point to

mixed effects of the air pollution control policies on air

quality. Agricultural burning policies and penalty fees

reduce the pollution from CO. Other policies such as the

prohibition on visible emission, fugitive dust, particulate

matter, nitrogen and the reduction of animal matter are

correlated with higher levels of CO. Regulations on or-

chard and citrus heaters have no significant effect on the

number of exceedances of the CO and NO2 standards.

Results of this research will lead to a better under-

standing of the regulations affecting air quality, and will

provide insight into the appropriate development of

management practice to mitigate air pollution problems.

The remainder of the paper proceeds as follows. The

next section provides background information on the

state of California with respect to air quality manag ement.

Section 3 describes the data. Section 4 presents the

methods and results from the econometric analysis. Sec-

tion 5 concl u d e s.

2. California’s Air Pollution Policy

The state of California is divided into fifty-eight different

counties and is overseen by the Governor of California.

California is divided into thirty-five air districts, which

are called either Air Pollution Control Districts or Air

Quality Management Districts. These air districts are

responsible for controlling air pollution from stationary

sources. Several air districts span the areas of many

counties, while some counties belong to different air dis-

tricts. Some air districts, such as the Great Basin Unified

air district, trace the division lines marking the regional

air basin [10].

The different air districts in California have their own

set of laws and regulations regarding stationary sources.

These laws and regulations are written by the authorities

within the air district and are applicable to the entire air

district. These laws and regulations must be at least as

stringent as the standards set by the federal government

[11].

The fact that each air district has its own set of laws

and regulations is crucial to the analysis of the policies

presented in this paper. The variation between the poli-

cies of the different air districts within the state of Cali-

fornia provides a setting for a natural experiment. Since

the different air districts all fall in the same state, they are

subject to the same federal and state laws. The districts

also share many other similar characteristics, for example

climate, geographical location, etc. The variation in air

quality over the time the different policies take place,

then, must be due mostly to the policies themselves and

not due to geographical location, climate or different

state laws. Thus, the variation in similar policies across

air districts enables one to better single out the effect of

policies on air quality and health.

Among the many different laws and regulations gov-

erning each of the thirty-five air districts in California,

this paper focuses on the following eight types of policy:

1) Agricultural burning: This policy regulates open

outdoor fires used in agricultural operations in the grow-

ing of crops, the raising of animals, the disposal of agri-

business waste, or for purposes such as forest manage-

ment, range improvement, irrigation system management,

etc. The policy requires burning permits and imposes

no-burn days.

2) Visible emissions: This policy provides limits for

visible emissions. In many districts, emissions from ag-

ricultural operations are exempt.

3) Fugitive dust: The purpose of this policy is to re-

duce the amount of particulate matter entrained in the air

as a result of anthropogenic fugitive dust sources by re-

quiring actions to prevent, reduce or mitigate fugitive

dust emissions.

4) Particulate matter: This policy imposes limits on

particulate matter emissions.

5) Nitrogen: This policy imposes limits on NOx emis-

sions.

6) Reduction of animal matter: This policy requires

that the gases, vapors and gas-entrained effluents from

any article, machine equipment, or other contrivance

used for the reduction of animal matter to be incinerated

or processed.

7) Orchard and citrus heaters: This policy regulates

orchard and citrus heaters.

8) Penalty fee: Station ary sources with the potential to

emit regulated pollutants (including nitrogen oxides,

VOCs, CO and PM10) above a certain amount need to

obtain permits to operate consistent with the require-

ments of Title V of the federal Clean Air Act as amended

in 1990. This policy req uires operators of units requiring

Title V permits to pay a penalty if they fail to pay for

their permit within a certain number of days after it is

issued.

California’s Agriculture-Related Local Air Pollution Policy

These eight policies were chosen because they were

similar in theme across the different counties in the dif-

ferent air districts but they either vary in whether they

were implemented at all, or differ in the date of imple-

mentation. For example, the prohibition on fugitive dust

applies in Amador and Imperial Counties but not in El

Dorado and Monterey Counties. Of Amador and Imperial

Counties, the dates of implementation of the prohibition

policy differ. In Amador County the policy did not take

effect until the year 2000, while the policy was imple-

mented in Imperial County prio r to 1994 [12].

The similarity of theme in the different policies chosen

and the difference in the details of each of the policy add

to the quality of th e analysis. Since the policies are simi-

lar in theme but are different in details, comparisons can

be made and the effect of each policy can be examined.

For example, once controls are taken into account, dif-

ferences between air quality in Amador County and El

Dorado County can be said to be attributable to the pro-

hibition on fugitive dust which is effective in Amador

County but not in El Dorado County. Likewise, the dif-

ferences in air quality in Amador County and Imperial

County can be attributed to the differences in the date of

implementation of the prohibition on fugitive dust.

3. Data Description

My work in [7] uses annual county-level data from 1980-

2000.

The policy variables used in [7] are constructed from

the California Air Resources Board’s online database of

state and county laws and regulations concerning air

quality in the different air districts [12]. For each of the

eight policies chosen, dummy variables for whether or

not the policy is in place for each county for each year

since 1980 to 2000 were constructed.

To measure air quality, [7] focuses on two agricu lture-

related air pollutants: CO and nitrogen dioxide (NO2).

For each pollutant, data on the number of days per year

exceeding the state standards as compiled by the Califor-

nia Air Resources Board are used. In particular, for CO,

the number of days exceeding the state’s 1-hour standard

for CO of 20 parts per million (ppm) and the number of

days exceeding the state’s 8-hour standard for CO of 9.0

ppm are used. For NO2, the number of days exceeding

state’s 1-hour stand ard for NO2 of 0.18 ppm is used.

The socio-economic data used in [7] are obtained from

the US Bureau of Health Professions’ Area Resource File.

Socio-economic data used in this paper include popula-

tion, per capita income and the percentage of county area

occupied by farms.

4. Econometric Analysis

In order to identify the effects of the chosen air quality

policies on air q uality, [7] estimates multivariable regr es-

sions that exploit the natural variation in policy among

the different air districts in California.

It is possible that the correlation between the regula-

tions and air quality reflect some omitted characteristics

such as socio-economic status that are correlated with

both regulations and air quality. To address the possibil-

ity of omitted variab les b ias, in [7 ] I u se a method similar

to that used by [9]: I include a rich set of covariates and

employ county fixed effects to capture any unobserved

characteristics of counties that are constant over time.

The control variables used are year, population, popula-

tion density, per capita income, and acres of farmland.

The Hausman test was used to determine whether con-

trolling for fixed effects was more appropriate than con-

trolling for rando m effects.

The natural variation of policy among air districts

mitigates the potential endogeneity of regulation, since

two neighboring counties that may share similar charac-

teristics and that may have similar levels of pollution

prior to the implementation of a particular policy, all else

equal, may still belong to different air districts.

The econometric model is:

01 2

pollution policy

itititi it











, (1)

where pollutionit is the value of the pollution variable

(number of days exceeding the state’s 1-hour standard

for CO, the number of days exceeding the state’s 8-hour

standard for CO, or the number of days exceeding state’s

1-hour standard for NO2) in county i in year t; policyit is

a dummy variable denoting whether or not the particular

policy under consideration was in place in county i in

year t; xit is a vector of controls (year, population, popu-

lation-density, per capita income, and percentage of

land-area that are farms); and ui is a county fixed effect.

The results for the effects of policy on air pollution are

presented in Table 4 of [7]. Because the results of the

Hausman test favored the fixed effects model for most of

the regressions, only the fixed effect results are reported.

These results point to mixed effects of the chosen air

pollution control policies on air pollutants. An agricul-

tural burning policy significantly reduces the number of

days exceeding the state standard for both 1-hour and

8-hour CO. Agricultural burning policies also reduce the

number of days exceeding the state standard for NO2, but

the effect is not significant at a 5% level. The results also

suggest that having prohibitions on visible emission, fu-

gitive dust, particulate matter, nitrogen and the reduction

of animal matter seem to be significantly correlated with

increasing pollution from both 1-hour and 8-hour CO.

These policies also increase pollution from NO2, but the

effect is not significant at a 5% level. The regulations on

orchard and citrus heaters have no significant effect on

the number of days exceeding the state standard for CO

California’s Agriculture-Related Local Air Pollution Policy

or NO2. A penalty fee has a significant negative effect on

the number of days exceeding the state standard for both

1-hour and 8-hour CO, but no significant effect on the

number of days exceeding the state standard for NO2.

None of the p olicies examined had a significant effect on

the number of days exceeding the state standard for NO2.

5. Conclusions

This paper reviews my previous work in [7], in which I

examine whether existing air pollution control policies,

particularly those targeted at agriculture, have succeeded

in improving air quality, as measured by the number of

exceedances of the CO and NO2 standards. Results from

the multivariable regressions point to mixed effects of air

pollution control policies on air quality, as measured by

the number of exceedances of the CO and NO2 standards.

Agricultural burning policies and penalty fees reduce the

pollution from CO. Other policies such as the prohibition

on visible emission, fugitive dust, particulate matter, ni-

trogen and the reduction of animal matter are correlated

with higher levels of CO. Regulations on orchard and

citrus heaters have no significan t effect on the number of

exceedances of the CO and NO2 standards.

The regulations that were most effective in improving

air quality were the regulations on agricultural burning

and the penalty fees for noncompliance with the stan-

dards.

These results provide insight into the appropriate de-

sign of policy to mitigate air p ollutio n problems and their

associated adverse health effects.

6. Acknowledgements

Kanittha Tambunlertchai provided excellent research

assistance. I thank Gary Chamberlain and John Karlik for

discussions. I received financial support from the Gian-

nini Foundation for Agricultural Economics, an EPA

Science to Achieve Results graduate fellowship, a Na-

tional Science Foundation graduate research fellowship,

and a Repsol YPF—Harvard Kennedy School Pre-Doc-

toral Fellowship in energy policy. I am a member of the

Giannini Foundation for Agricultural Economics. All

errors are my own.

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