Air Quality Impacts 

in the Border Region

Presentation to GNEB

March 24, 2011

Sue Stendebach, EPA
Uniquely Varying Border Zones

Geography, topography, geology, temperature, 

humidity, amt. of sunlight, wind patterns, population, 

industry, socioeconomic factors, etc. all contribute to

defining:

Types and volume of man-made air pollutants (criteria 

and GHGs) 

Natural sources of air pollution

Distribution of pollutants

Impacts of pollutants

Options for mitigating pollution

Conditions for renewable energy
Examples of Regional Variability and Effects

 Windblown dust from open desert and plains, agricultural practices and 

unpaved roads.

 San Diego - Tijuana air basin -- prevailing winds are north to south, while 

in Imperial - Mexicali, winds blow fairly evenly in both directions, 

depending on the season. 

 In border air basins with large populations and along main trade corridors, 

vehicle emissions will be high and concentrated, leading to both health 

impacts and contribution to climate change. These are exacerbated by 

idling vehicles at busy ports-of-entry. 

 In lower socioeconomic areas, vehicles may be older and therefore more 

polluting. Residential areas situated close to border crossings often house 

poorer populations, exposing community to higher rates of pollution.

 Due in part to high concentrations of PM10, Imperial County has the 

highest rate of childhood asthma in California.

 California and Baja California terrain and wind patterns result in the 

greatest wind power potential in the border region, while Arizona-Sonora 

and New Mexico - Chihuahua hold the greatest solar prospects.

 Mexicali has a huge geothermal field that fuels a 700 MW energy 

generation facility. Imperial County has 10 small facilities fueled by 

geothermal, producing 327 MW of energy.
Major Criteria Emissions Sources 

in the Border Region 

Vehicles:

 In the U.S. and Mexico border region, many millions of vehicles 

already in use continue to emit relatively large amounts of nitrogen 

oxides (NOX) and fine particulate matter.

 These pollutants contribute to serious health conditions, such as 

asthma, and can worsen heart and lung disease. 

 Diesel vehicles additionally emit black carbon and carbon dioxide, 

which contribute to global climate change.

 New clean vehicles and ultra-low sulfur fuels in the U.S. will 

continue to lower these emissions as fleets turn over.

 Mexico is tightening vehicle emissions standards, but ultra-low 

sulfur diesel will not be nationally available until late 2014.

Energy Generation:

 Despite controls, fossil fueled energy generation facilities emit 

sulfur dioxide, nitrogen oxides, mercury , carbon dioxide and other 

pollutants.
Current U.S. O3 and PM Standards 

Ozone: 

Currently, 0.075 ppm 8-hour standard

EPA proposal lays out a range of 0.060 to 0.070 

ppm for consideration to replace current 8-hour 

standard.

Final rule anticipated this summer.

PM10: 

150 μg/m3 (24-hour average standard); 

50 μg/m3 (annual standard)
O3 Monitoring Stations
0.06

0.07

0.08

0.09

0.1

2001 2002 2003 2004 2005 2006 2007 2008 2009

Ozo

n

e (p

p

m)

Ozone Concentrations in the Border Region 

--- DRAFT ---

Tijuana-San Diego

Mexicali/Imperial Valley

Nogales (U.S.)

Ciudad Juarez/El Paso

Lower Rio Grande Valley (U.S.)

Standard (8hr avg: 0.075 ppm;

2008 standard)
PM10 Monitoring Stations
0

50

100

150

200

250

300

2001 2002 2003 2004 2005 2006 2007 2008 2009

PM10 (ug/m3

)

PM10 Concentrations in the Border Region

--- DRAFT ---

Tijuana-San Diego

Mexicali/Imperial Valley

Nogales (U.S.)

Ciudad Juarez/El Paso

Lower Rio Grande Valley (U.S.)

U.S. Annual Standard (50 ug/m3)
O3 and PM10 Exceedances

--- DRAFT ---

54

28

37

24

9

8

1

5

0

10

20

30

40

50

60

70

2

0

0

6

2

0

0

7

2

0

0

8

2

0

0

9

Days Exceeding Standard

Tijuana-San Diego

O3 PM10

59

50

25

19

41

35

40

17

0

10

20

30

40

50

60

70

2

0

0

6

2

0

0

7

2

0

0

8

2

0

0

9

Days Exceeding Standard

Mexicali/Imperial Valley

O3 PM10
O3 and PM10 Exceedences

--- DRAFT ---

5

2

5

1

48

16

14 13

0

10

20

30

40

50

60

70

2

0

0

6

2

0

0

7

2

0

0

8

2

0

0

9

Days Exceeding Standard

Ciudad Juarez/El Paso

O3 PM10

10

0

2 2

42

14 13

2

0

10

20

30

40

50

60

70

2

0

0

6

2

0

0

7

2

0

0

8

2

0

0

9

D

a

ys Exce

e

din

g

Sta

n

d

ard

Nogales (U.S.)

O3 PM10
Asthma -- Case Study

• Imperial County has the highest rate of childhood 

asthma hospital admissions in California.

• In 2003, children 0-14 years old were admitted to the 

hospital because of asthma -- more than three times 

the state average. Nearly 85% of these hospital 

admissions occurred among Latino children.

• Higher percentages of asthma among students than in 

other parts of California.

• Higher percentages of asthma than a national 

comparison group.

• As of 2009, children in Imperial County were still three 

times more likely to be admitted to the hospital for 

asthma than in the rest of the State.
Current Border Population
0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

2005 2010 2015 2020 2025 2030

P

o

p

ulatio

n

Border Region Population and 

Forecast Population Growth: 2005-2030

--- DRAFT ---

Actual Population (US and Mex; 2005) Projection: Low Scenario (US and Mex)

Projection: Medium Scenario (US and Mex) Projection: High Scenario (US and Mex)
$0

$50

$100

$150

$200

$250

$300

$350

$400

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

Tra

d

e

Valu

e (Billio

ns)

Value of Land-based Freight Movement 

Across the U.S.- Mexico Border 

---DRAFT ---

Exports from U.S. to Mexico Exports from Mexico to U.S.
3.80

4.00

4.20

4.40

4.60

4.80

5.00

2002 2003 2004 2005 2006 2007 2008

Millions

Number of Northbound Truck 

Crossings at the U.S.-Mexico 

Border Per Year --- DRAFT ---

72

74

76

78

80

82

84

86

88

90

92

94

2002 2003 2004 2005 2006 2007 2008

Millions

Number of Northbound Passenger 

Vehicle Crossings at the U.S.-Mexico 

Border Per Year --- DRAFT ---
Increased Trade  Increased Emissions along 

Trade Corridors and at POEs

 Today, goods shipped by truck comprise more than 70 

percent of U.S. – Mexico trade, according to ATA. 

 In 2009, the Laredo port-of-entry was the busiest, with 

an estimated 1.4 million northbound trucks crossing 

the border. 

 That same year, Otay Mesa ranked second, with more 

than 684,000 northbound crossings.

 For December, 2010, U.S.-Mexico surface 

transportation trade rose significantly in value from 

December 2009, although not as high as in 2008. 

• Imports by 16.3%

• Exports by 18.7%
Proposed U.S.-Mexico Long-Haul Trucking 

Program

 Presidents Obama and Calderon have agreed to a reciprocal 

phased-in program for opening border to long-haul trucks.

 Needs Congressional approval

 Public comment period

 Mexico would lift tariffs completely once program begins.

 Safety, security and emissions requirements must be met for 

Mexican trucks/drivers to become certified for participation in the 

program.

 For emissions purposes, Mexican truck engines must bear an EPA 

certification label for the year of manufacture.

 Issue: For U.S. model year 2007 or newer trucks traveling in 

Mexico, ultra-low sulfur diesel will not available nationwide until 

November 2014, which is necessary to maintain the integrity of the 

diesel particulate filter. (DPFs)

 DPFs reduce PM by greater than 90% .
Air Emissions Impacts of Increase 

in Long-Haul Trucks

Speculative at this point:

 Would likely see fewer drayage trucks hauling goods from Mexico 

to transfer stations within the 20-mile commercial zone.

 Because of long-haul durability demands, would likely see newer, 

and thus cleaner, trucks than those used for drayage.

 Over time, trade would likely increase such that the number of 

long-haul trucks would be greater than the drayage trucks they 

replace. Total truck volume would then translate into increased 

wait times at POEs, and thus more idling emissions.

 However, it’s possible, at least in the short- to mid-term, that an 

increase in cleaner long-haul trucks and decrease in dirtier drayage

trucks could make the additional idling emissions a wash.

 What combination of integrated mechanisms could the U.S. 

undertake to decrease idling and increase security and safety?
Anti-Idling at Points of Entry

 The Joint Working Committee on Transportation Planning recently 

hosted a very successful workshop on greening transportation at 

the border.

 Numerous presenters addressed truck and passenger car emissions 

as one of many aspects to be considered in greening POEs. 

 In response to the Board’s recommendation to address anti-idling 

at ports-of-entry, EPA is working with CEQ, the JWC, FHWA and 

other agencies to explore viable approaches that complement 

those aimed at assuring security and safety. 

 As a bonus, anti-idling mechanisms provide the opportunity to 

achieve co-benefits -- decreasing both criteria pollutants and GHGs 

simultaneously.
Border Projects & Significant Impact

 Through the El-Paso Juarez area Joint Advisory 

Committee (JAC), Region 6 helps support local, 

binational planning and projects.

 The “One Basin Resolution” for the Paso del Norte area 

will facilitate robust monitoring, vehicle inspection, and 

efforts toward "harmonization" of standards.

 Recently added MPOs to JAC will expand ability to 

address emissions.

 Technical/policy assistance in development and update 

of Ciudad Juarez “ProAire” (SIP-type tool)

 Mobile source reductions through congestion 

mitigation, I&M, in Juarez, Smartway. 

 These and other efforts brought El Paso into

attainment for the Ozone, CO, and PM10 NAAQS.
Border Projects & Significant Impact

Moving to Region 9 -- assisted states and local 

governments in and adjacent to nonattainment 

areas (both sides of the border) by:

School bus and heavy-duty truck retrofits

Fuel efficiency demonstrations 

Landfill methane recovery

Road paving

Active Border 2012 Task Forces

Intensive assistance with Baja monitoring network

Exploring one basin approach in Imperial-Mexicali 

area
Future Challenges and Necessary Support

 Potential for El Paso to slip back into ozone nonattainment with 

new 8-hr. Standard.

 El Paso County still has some monitors showing PM10 nonattainment.

 Sunland Park is close to the current PM 2.5 standard, with unpaved 

roads and wood burning stoves contributing.

 New areas could fall into nonattainment with new ozone rule, and 

potential PM standard changes in the future.

 Security issues affecting technical support for AQ monitoring 

networks in El Paso, as well as other capacity – building.

 Seeking cross-border emissions transport guidance as new ozone 

and PM standards are developed – CAA provision allowing 

international transport to be taken into consideration in 

implementing NAAQS.

 Replication of bi-national cooperation if new areas (e.g. Valley, 

Laredo, etc.) become nonattainment and strategies for new source 

types (e.g. agriculture).

Future Challenges and Necessary Support

 Further road paving in Sonora and Baja is critical

 Control of agricultural burning

 Assistance with smog checks in MX

 Diesel truck idling at border crossings – hot spots; environmental justice

 Operation of a well maintained air quality monitoring network in Mexican 

border cities (Ambos Nogales, Agua Prieta, San Luis Rio Colorado, northern 

Baja)

 Baja government has minimal resources to maintain and read monitors

 Possible for national AIRNow-International project in Mexico to assist

 Adequate resources necessary, especially for Mexico, to take actions to 

reduce emissions. Example: additional NADBank loans and BEIF-like 

funding for road paving

 Imperial-Mexicali binational cooperation in managing cross-border air 

basin, using JAC as model. Strong local support is necessary to make this 

approach viable.

 Further reduction of GHG reductions from cleaner transportation, 

methane recovery, energy efficiency, binationally.

 New national fuel economy/GHG reductions regulations will help 

immensely. 

EPA and others working with Mexico to provide assistance on similar rule.


Thank You.

Contact Information:

Sue Stendebach

EPA Office of Air and Radiation

202-564-8309

stendebach.sue@epa.gov