Human Health and
Environment
2.1
Human Health and Environmental Need
PM10 can be
defined as solid or liquid particles, such as dust, ash, metallic particles,
cement, or pollen that are dispersed in the atmosphere and have a diameter
equal or less than 10 microns. Some
elements can be associated with these particles, such as lead, arsenic,
beryllium, cadmium, mercury, sulfates, nitrates and aromatic hydrocarbons.
The determining factor in
the impact on human health is the particle size, due to the capabilities
to penetrate and remain in the respiratory system. The majority of the
particles whose diameter is less than 5
microns are deposited in the superior respiratory parts, in the traquea and the
bronchia.
The impacts on human health related to long exposures
to fine particles include:
a.
Irritation of the eyes and nose
b.
Increase in the incidences of respiratory diseases
c.
Asthma
d.
Reduction in lung efficiency
e.
Increase in respiratory symptoms
Once these particles are deposited in the respiratory
system, its irritating capabilities is due to its chemical composition and its
toxicity, and its capabilities to absorb and adsorb other compounds in its
surface.
In 1996, the U.S. Environmental Protection Agency (EPA)
published the document Air Quality Criteria for Particulate Matter. This
document has an evaluation of particulate matter in human health. Part of the
conclusions of the document express the fact that most of the health problems
suggest exposure to particulate matter in the air in the short- and long-term.
The Mexican Official Norm NOM-025-SSA1-1993 determines
the maximum limits of PM10 concentrations in the air. The limits are
50 mg/m3
as an annual average for chronic exposure, and 150 mg/m3 in a
24-hour period once a year for acute exposure. It is important to mention that
the U.S. standard for PM10 particles are the same as the Mexican
standards.
The following section presents the date from the
monitoring stations obtained in Tijuana and Mexicali. Ensenada and Rosarito do
not have monitoring stations, and Tecate has a monitoring station that is part
of the results presented for Tijuana.
Mexicali
Since 1996, the City of Mexicali operates several
monitoring stations for air quality. The reports from the monitoring stations
indicate that PM10 is the major contributor to air quality problems
in the City. There is an emissions inventory (data since 1996)
[www.ine.gob.mx/dgicurg/calaire/difusion.html] that indicates that 63 percent
of the PM10 volumes (53,689 tons/year) is originated due to cars
traveling through unpaved streets. According to 1997 data, the Official Norm
for air quality was exceeded 91 days of the year.
The following table presents annual average data for PM10
in various locations in the Mexicali area:
|
|
Annual average of PM10
(mg/m3)
|
|
|
Station
|
1998
|
1999
|
2000
|
2001
|
|
|
|
Tecnológico
|
48
|
58
|
62
|
52
|
|
|
UABC
|
81
|
87
|
96
|
79
|
|
|
CBTIS
21
|
49
|
54
|
54
|
45
|
|
|
COBACH-BC
|
128
|
151
|
169
|
136
|
|
|
CONALEP
|
67
|
85
|
71
|
67
|
|
|
Col. Progreso
|
148
|
194
|
265
|
217
|
|
It is clear from the data presented that the PM10
concentrations exceed the official norms for chronic exposure.
According to the Municipal Development Council of
Mexicali (Consejo de Urbanización Municipal de Mexicali) the following
surfaces have been paved in the past years:
|
Year
|
Area (m2)
|
|
1997
|
87,365
|
|
1998
|
80,177
|
|
1999
|
70,147
|
|
2000
|
65,596
|
|
2001
|
73,833
|
|
2002
|
78,375
|
This information has been analyzed according to the
method described in the following section, in order to evaluate the reductions
in PM10 particles due to street paving:
|
Year
|
Reduction of PM10
(Tons/year)
|
|
1997
|
645
|
|
1998
|
592
|
|
1999
|
518
|
|
2000
|
484
|
|
2001
|
545
|
|
2002
|
579
|
The average reduction of PM10 particles per
year is 560 tons. Considering a generation of 53,689 tons per year of PM10
particles, the average efforts for street paving reduces PM10
particles by 1 percent. Therefore it is necessary to increase the rate of
street paving to protect human health by reducing the particulate matter in the
atmosphere.
Tijuana
The City of Tijuana has a total of 6 monitoring
stations that measure concentrations of O3, NO2, SO2,
and CO, as well as temperature, relative humidity, wind direction and velocity,
and suspended particles and PM10. Two additional stations in Tijuana
measure suspended particles and PM10.
The following table presents the annual average data
obtained throughout the City of Tijuana:
|
|
Annual average PM10
(mg/m3)
|
|
|
Station
|
1998
|
1999
|
2000
|
2001
|
|
|
|
Tecnológico
|
48
|
55
|
51
|
45
|
|
|
Centro
de Salud
|
49
|
58
|
51
|
51
|
|
|
La
Mesa
|
65
|
66
|
59
|
65
|
|
|
Playas
de TJ
|
38
|
42
|
38
|
36
|
|
|
Rosarito
|
-
|
-
|
61
|
51
|
|
The data obtained in the Tijuana monitoring stations
shows that in most cases, the PM10concentrations exceed those
allowed in the Mexican official norms for chronic exposure.
According to the emissions inventory for Tijuana, 76 percent
of the 23,563 tons/year of PM10 generated in the area originate from
vehicle circulation over unpaved streets.
An important factor in the City of Tijuana is the
excessive rate of urban growth. It is impossible for the City to keep up with
the growth and provide adequate services. This project is justified in order to
eliminate part of the backlog of street paving in the area generated by
excessive growth in the City. Street paving in the region can seriously improve
air quality and human health.
One last observation relates to the fact that the
monitoring stations are located within the urban centers and do not reflect the
PM10 concentrations in the areas mentioned of excessive growth,
where most of the unpaved streets are found.
Methodology to estimate the PM10
reduction by street paving
The model suggested by the U.S. EPA AP-42 Compilation
of Air Emission Factors was used in order to determine the dust emissions from
vehicle circulation on unpaved streets. The model also provides results for dust
emissions resulting from vehicle circulation on paved streets. Then the
difference was obtained from circulation over unpaved streets and paved streets
to determine the benefit of paving streets.
The model used to determine PM10 particles
generated in unpaved streets is the following:
E = k (s/12)a (W/3)b
----------------------
(M/0.2)c
where:
E = Emissions of particulate matter in pounds
(lb) per vehicle miles transited (VMT)
S = Clay contents in the surface material (%)
W = Average weight of vehicles circulating
through the street (ton)
M = Moisture content of the surface material (%)
In addition, k, a, b, and c
are constants obtained from direct measurements and relative to the particulate
matter that is being estimated. For PM10 the following apply:
|
Constant
|
PM10
|
|
k
(lb./VMT)
|
2.6
|
|
a
|
0.8
|
|
b
|
0.4
|
|
c
|
0.3
|
On a different note, the model used to estimate
particulate matter generated on paved streets is the following:
E
= k (sL/2)0.65 (W/3)1.5
Where,
E = Emissions of particulate matter in the units
of k (lb/VMT)
k =
Multiplying factor based on the size of the particulate estimated
W = Average weight of vehicles circulating
through the street (ton)
sL = Load of particulate matter over the street (g/m2)
The multiplying factor for k relative to PM10
and in units of g/VKT (grams per vehicle kilometer transited) is 4.6.
These factors, in units of weight over total kilometers
transited, were multiplied for every year and the number of paved kilometers to
obtain the reduction in the contribution of PM10 emission:
D = [Estreets
without paving Epaved streets] x Kmpaved x
Transitvehicles/year
Where D is the reduction in the PM10
emissions due to traffic over unpaved streets in tons per year.
Model for PM10 pollution reduction
in Mexicali
In the case of Mexicali, the following values were
used: clay percentage [11%], humidity contents
[1.3%], average
vehicle weight [1.9 tons].
The information was obtained from the Municipal
Development Council. The streets that are proposed for paving are mostly
residential streets with an width varying from 6 to 10 meters and a traffic
volume of 200 to 800 vehicles per day.
For purpose of the model, an average street width of 8 meters will be
considered, as well as 500 vehicles per street per day.
The projections for the purpose of this study are
consistent with the timeline of this project: from 2003 to 2007. The following
table presents the results of the modeling:
The emissions factor for traffic over unpaved streets
is E = 324.53 g/ VKT, which is to say that for every kilometer transited, a
total of 324.53 grams of PM10 are released to the atmosphere. The
value from the emissions inventory for Mexicali is 306.53 g/VKT, which is very
similar to the one obtained as part of this model.
The emissions factor for traffic over paved streets is
estimated at E = 0.81 g/VKT, which represents 0.81 grams of PM10
released for every kilometer transited. The previous table presents the
reduction of PM10 obtained by street paving.
Model for PM10 pollution reduction
in Tijuana
The same values were considered for the Tijuana model
as for the Mexicali model. Even though the particular values might change from
community to community, for purposes of the model, the reductions in PM10
particles due to paving should not change significantly.
The same values were used for Tijuana for the model: 8
meter average street width and 500 vehicles per day per street.
The projected surface paved for Tijuana is as follows:
Applying the methodology described previously and the
constants assumed for the model, we have the following results:
Just as in the case of Mexicali, the emissions factor
for traffic over unpaved streets is E = 324.53 g/ VKT, which is to say that for
every kilometer transited, a total of 324.53 grams of PM10 are
released to the atmosphere, and the emissions factor for traffic over paved
streets is estimated at E = 0.81 g/VKT, which represents 0.81 grams of PM10
released for every kilometer transited
SAHOPE has prepared an environmental document, in the
form of an Informe Preventivo in order to comply with the State environmental
requirements. The determination of impact by the State of Baja California is
expected on late-February, 2003.
Environmental Laws and Regulations
The purpose of this project is to improve air quality
and comply with the Mexican Official Norm NOM-025-SSA1-1993, which determines
the maximum limits for PM10 concentration in the atmosphere.
Technical
Feasibility
Both asphalt and hydraulic
pavement are being considered for this project. The following section describes
the justification for choosing each particular type of pavement.
It is important to
mention that in the Imperial Basin
(Mexicali area) asphalt pavement will be used. In the San Diego Basin
(Ensenada, Rosarito, Tecate, and Tijuana) hydraulic pavement will be used.
The use of asphalt
pavement in Mexicali will allow lower maintenance costs, due to the fact
that it doesnt crack as often due to its flexible properties. This is
important in excessively hot places, such as Mexicali.
Also, due to the fact that the Mexicali area does not
experience frequent rain events, the asphalt pavement lasts longer. In
addition, asphalt pavement is recommended in areas with high clay and
heterogeneous soils due to the fact that it is better fit for soil
displacements.
Asphalt pavement does not have joints, which prevents
dust deposits, thus providing a better design to reduce particle emissions.
Present value
The use of asphalt pavement is better once cost
considerations are taken into account. A present value analysis determines that
asphalt pavement is better suited for the Mexicali area.
A: Cost of
asphalt pavement
B: Sealing after 7 years.
C: Recarpet at 12 years.
D: Sealing at 19 years.
|
|
Analyzing the costs of asphalt pavement and its
maintenance cost after 20 years and taking into account a 4 percent inflation
factor, the present value is as follows (per m2):
Cost of asphalt pavement: $171.237
Cost of sealing after 7 years: $31.25 and a present
value of $41.22
Cost of recarpeting after 12 years: $115.53 and a
present value of $184.96
Cost of sealing after 19 years: $31.25 and a present
value of $65.83.
Adding these costs brings the cost of installing the
asphalt pavement and maintaining it at: $463.24 per m2.
A: Cost of hydraulic pavement
B: Sealing after 8 years.
C: Sealing after 16 years.
D: Replacement of damaged hydraulic concrete after 20
years.
|
|
The following is a present worth analysis of hydraulic
pavement:
The following present value analysis assumes a 4
percent inflation rate (per m2):
Cost of hydraulic pavement: $256.27
Cost of sealing after 8 years: $62.5 and a present
value of $85.53
Cost of sealing after 16 years: $62.5 and a present
value of $117.06
Cost of replacing damaged hydraulic pavement after 20
years: $10.43 and a present value of $22.85
Once these costs are added, the present value of
installing and maintaining hydraulic pavement is $481.70 per squared meter.
In comparison, we can see that the cost of hydraulic
pavement is lower than the cost of asphalt pavement, but once the maintenance
costs are added, we can see that the asphalt pavement present value is lower
than hydraulic pavement.
Installed capacity
Tijuana-Rosarito
The Cities of Tijuana and Rosarito have 6 firms that
fabricate hydraulic concrete for paving. These firms have a production capacity
of 8,400 m3/day and produce 2,184,000 m3 per year. Also,
these firms have 5 factories of asphalt concrete and a capacity to produce
2,140 m3/day and 556,400 m3 annually.
Ensenada
The City of Ensenada has 5 firms that produce hydraulic
concrete with a total capacity of 1,080 m3/day and an annual
production of 280,800 m3. In addition, they have 2 factories
producing asphalt concrete with a daily capacity of 480 m3, and an
annual capacity of 124,800 m3.
Tecate
The City of Tecate has 1 firm that produces hydraulic
concrete with a daily capacity of 400 m3 and an annual capacity of
104,000 m3. There are no firms producing asphalt concrete.
Mexicali
The City of Mexicali has 5 firms producing hydraulic
concrete with a daily capacity of 4,520 m3/day and an annual
capacity of 1,175,200 m3. It also has 6 firms producing asphalt
cement with a daily capacity of 2,450 m3/day and an annual
production of 637,000 m3.
The following table presents the required volumes of
hydraulic concrete:
|
Municipality
|
Volume required m3/year
|
m3 / day
|
m3 / year
|
Utilization percentage
|
|
TIJUANA
ROSARITO
|
329,000
|
8,400
|
2,184,000
|
55
|
|
ENSENADA
|
74,769
|
1,080
|
280,800
|
60
|
|
TECATE
|
24,500
|
400
|
104,000
|
50
|
|
MEXICALI
|
-
-
|
4,520
|
1,175,200
|
60
|
|
TOTAL
|
428,269
|
|
3,744,000
|
|
The following table presents the required volumes of
asphalt concrete:
|
Municipality
|
Volume required m3/year
|
m3 / day
|
m3 / year
|
Utilization percentage
|
|
TIJUANA - ROSARITO
|
109,571
|
2,140
|
556,400
|
40
|
|
ENSENADA
|
- -
|
480
|
124,800
|
15
|
|
TECATE
|
- -
|
- -
|
- -
|
- -
|
|
MEXICALI
|
30,250
|
2,450
|
637,000
|
40
|
|
TOTAL
|
139,821
|
|
1,318,200
|
|
The operation and maintenance of the paved streets will
be responsibility of the municipalities where the project is executed.
There is final design for the street paving. As it was
indicated both hydraulic and asphalt pavement will be used, depending on the
City. There is final design for each type of paving material.
Financial Feasibility
4.1
Financial Feasibility
The cost of the first
phase of the project is estimated at $494,000,000 pesos ($47 million dollars assuming
an exchange rate of 10.5 pesos to the dollar.) The cost of the overall project
in 5 years is $4,634,000,000 pesos. The NADB performed a loan analysis for the
project. In addition to the NADB loan, the Federal and State Governments will
provide funding for the project, as well as each Municipality. The NADB loan
will be used to pay for the citizens contribution to the project. The
repayment period for the citizens will be 12, 24, 36, or 48 months. The
following tables presents the funds identified for the first phase of the
project, as well as the contribution by the citizens.
Project Costs
(Phase 1, in million pesos)
|
Concept
|
Amount
|
Percentage
|
|
Cost of project
|
439.1
|
100%
|
|
State
Government
|
123.7
|
28%
|
|
Municipalities
|
123.7
|
28%
|
|
Total from Governments
|
247.4
|
56%
|
|
Down payment Citizens
|
22
|
5%
|
|
Loan
NADB
|
197.6
|
45%
|
|
Total
Funding
|
466.9
|
106%*
|
*Includes cost for supervision
and contingencies.
Project cost and
contributions by citizens (in pesos)
|
Paving cost per citizen (average): $12,000
|
|
Contributions
|
|
Government
|
$7,200
|
60 %
|
|
Citizens Cost of project
|
$4,800
|
40 %
|
|
Total
|
$12,000
|
100
%
|
|
Charged to citizens
|
|
Project
cost
|
$4,800
|
|
|
Administrative cost
@ 10%
|
$480
|
|
Total
|
$5,280
|
Payments by
Citizens (in pesos)
|
Paving cost per citizen (average): $12,000
|
|
Charged to citizens
|
$5,280
|
|
Down payment (10%)
|
$528
|
|
Payment in installments
|
$4,752
|
|
Total
paid
|
$5,280
|
|
Repayment period
|
Monthly installment
|
Total
payments
|
|
12
months
|
$442
|
$5,310
|
|
24
months
|
$244
|
$5,861
|
|
36
months
|
$179
|
$6,445
|
|
48
months
|
$147
|
$7,063
|
|
Interest rate
|
|
12 % (annual)
|
|
Operation cost of project
|
|
5.7
% (annual)
|
|
Interest rate charged to citizen
|
17.7 % (annual)
1.48 % (monthly)
|
There will be no rates established for this project
besides the cost to repay the loan.
The
State Development Authority (SDA) will administer this project. The Development
Authority is a decentralized public agency with the authority to perform public
works, as well as its administration. The SDA has jurisdiction throughout the
State of Baja California and is based in the capital, Mexicali. Its boards are
formed by a representative from the State Governor, who acts as its president
and also the following members:
1. The
Governors Secretary
2. The
State Finance Secretary
3. The
State Development Secretary
4. A
representative from the State Real Estate Agency
5. A
representative from the State Development Agency for Rural Areas
6. A
representative from the State Institute of Housing
7. A
representative from the State Chamber of Commerce and Tourism
8. A
representative of the State Chamber of Industry
9. A
representative of the Private Sector
10. A
representative from the State College of Engineers and Architects
11. A
representative from the State Banks
12. A
representative from the providers of public works in the State
13. A
representative of the Real Estate agencies in the State
14. A
representative of the workers unions
15. A
representative of the larger farmers unions
Also,
the Mayors of the Cities and the Directors of the local utilities are members
of the SDA. The SDA also has a General Manager appointed by the State Governor.
Characteristics
of the SDA
These
are some of the functions and responsibilities of the SDA:
1. Carry
out technical studies related to infrastructure projects as considered by SAHOPE
2. Execute
projects approved by SAHOPE
3. Prepare
bid documents according to the Public Works law
4. Receive
and sign loan documents
5. Follow
up on construction contracts
6. Establish
equity taxes on property affected by public works
7. Charge
for the cost of the public works.
