This paper was presented at the Air Pollution conference in Athens in 2012. Describes research done at the Aburra Valley during the change in sulfur content of the diesel fuel

1. THE EFECT OF THE DIESEL FUEL SULPHUR CONTENT ON THE PM2.5 POLLUTION
PROBLEM IN THE ABURRÁ VALLEY REGION AROUND MEDELLÍN, COLOMBIA
E. Posada (1), M. Gómez (2)
(1) INDISA S.A ,Carrera 75 # 48 A 27, Medellín, Colombia
(2) Politécnico Colombiano, Medellín, Colombia
Presenting author email: enrique.posada@indisa.com
co-author mgomez@elpoli.edu.co
ABSTRACT
The Aburrá Valley region has 3.5 million people, including the city of Medellín. Diesel fuel went down from 2,100 ppm
to 500 ppm and then to 50 ppm, between the end of 2009 and the first six months of 2010. A study was made to
determine the impact on the PM2.5 environmental concentrations and on the chemical composition of the PM2.5 matter.
This was done by taking PM2.5 samples in several sites and doing chemical analysis on the samples, which included
metals, anions and cations and carbonaceous matter (EC and OC). The study included samplings in a vehicle tunnel
serving the city and emission sampling in a laboratory diesel fuel motor. A clear link was established between diesel
sulphur content and PM2.5 compositions and concentrations, which indicates the large influence of diesel fuel vehicles
impact on the pollution situation in the region and the importance of this sulphur diminution.
1. INTRODUCTION
The Aburrá Valley region in the Andean range of Colombia, has 3.5 million people, with the city of Medellín
at its centre. It is a region surrounded by high mountains with relatively poor ventilation. Under the pressure
of the environmental authorities, the national provider of diesel fuel decided to supply to the region low
sulphur diesel, to contribute to the lowering of the PM2.5 concentrations in the air. S contents went down from
2,100 ppm to 500 ppm and then to 50 ppm between the end of 2009 and the first six months of 2010. This
change came after a long period of time in which most of the emphasis of the air pollution problem was laid
upon industrial sources. Despite the programs developed for industrial control, not much favourable change
was noticed in the urban PM concentrations, so finally the authorities began attacking the problem of mobile
sources pollution, which has been steadily growing with the increase in population and traffic. Although the
region counts with a metropolitan metro train and innovative cable mass transportation systems, there are still
large amounts of diesel operated buses and trucks, of which many are somewhat old and operated under
inefficient conditions which produce frequently black smoke visible fumes.
It is well known that sulphur content of diesel fuel
contributes largely to the emission of particulate
matter in diesel operated vehicles. Condensed
sulphates coming from sulphur tend to enclose
soot masses, protecting them from oxidation and
destruction (see figure taken from Matti
Maricq,M.).
It is also well known that diesel engines generate
much larger PM emissions than gasoline engines.
Table 1, (based on low estimate emission data
adapted from Geller,M, et al, with vehicle and
high estimate emission data taken from Toro M.
Et al), shows a comparative estimation of yearly
PM2.5 vehicle emissions for the studied region.
The estimates presented vary largely due to the
effect of vehicle age, pollution control devices
employed and operational conditions. The
assumed estimates for the region consider the
existence of significant amounts of older vehicles, Figure 1. Artistic conception of diesel PM – taken
lack of pollution control devices and low from Matti Maricq, M.
operative standards.

2. Table 1. Estimated yearly PM2.5 vehicle emissions in the Aburrá Valley region
Type of vehicle Units Diesel Gasoline Total
Number of vehicles 86,972 571,109 658,081
Distance travelled per vehicle-year Km 20,000 6,000 7,850
Emission factor for PM2.5 , low estimate mg/km 7.57 0.35 2.78
Emission factor for PM2.5 , high estimate mg/km 468.0 41.6 185.2
Emission factor for PM2.5 , laboratory study mg/km 221.9 ND
Yearly emissions, assumed estimate tons/year 600 105 705
Under the support of the Area Metropolitana del Valle de Aburrá (the regional environmental authority) and
ECOPETROL (the national petroleum company) a research project was undertaken to examine the effect of
the lowering of the diesel sulphur content on the PM2.5 composition and concentration. There is considerable
data in the region on total PM, which has been studied since the early 80’s and some data on PM 10, taken in
the last five years. But PM2.5 has been studied only in a few sampling stations during the last two years.
Table 2 shows the studied PM2.concentrations for five zones in the region (24 hour samples) before the
sulphur content of the diesel fuel was lowered. Samples of table 2 were taken in 2009 and the first five
months of 2010. The established annual standard for air quality in this area is 25µg/Nm3 . The table also
shows the major chemical compositions (taken from Gomez et al and this study)
Table 2. PM2.5 concentrations in stations in the studied region, micrograms/Nm3 and PM2.5
chemical composition (average % +/- 1.5 standard deviations) before changes in S content in diesel
Stations Unal Poli S. Antonio Bello Itagüí All stations
Samples 7 7 38 30 30 112
PM 2.5 conc. 27.6+/-6.7 32.7+/-17.4 37.2+/-9.6 43.1+/27.7 25.9+/-10.7 33.7+/-17.6
OC 20.7+/-4.3 25.14+/-4.5 20.48+/-5.1 25.68+/-6.4 26.02+/-5.5 23.78+/-4.3
EC 40.11+/-5.0 23.31+/-5.7 37.18+/-7.0 30.4+/-10.5 26.56+/-7.0 31.53+/-7.6
Sulfates 12.66+/-2.6 16.26+/-3.4 15.35+/-7.6 13.9+/-2.41 15.1+/-4.62 14.69+/-3.3
Nitrates 0.35+/-0.11 0.62+/-0.21 1.35+/-1.46 0.75+/-0.42 1.33+/-1.16 0.98+/-0.73
Sodium 1.21+/-0.35 1.92+/-0.67 1.26+/-0.68 1.23+/-0.32 2.87+/-1.74 1.71+/-0.93
Ammonium 4.01+/-1.38 4.68+/-1.71 5.28+/-2.52 4.23+/-0.98 3.87+/-1.42 4.44+/-1.23
SO3 1.09+/-0.29 1.45+/-1.22 0.46+/-0.74 1.21+/-0.67 0.65+/-0.47 0.90+/-0.58
SiO2 1.36+/-0.67 1.86+/-0.95 1.04+/-0.83 1.07+/-1.56 1.64+/-1.01 1.33+/-0.79
Fe2O3 0.64+/-0.45 0.99+/-0.79 0.65+/-0.46 0.82+/-0.36 0.76+/-0.21 0.76+/-0.30
2. METHODOLOGY
Laboratory emission sampling in a diesel motor bench. This was using a motor (ISUZU 4JA1 Type I
turbocharged, rotating pump direct injection, 2499 cm3, four cylinders in line, compression ratio 18.4,
nominal power 59 KW at 4100 rpm), working with fuel with three sulphur contents: 2,100, 500 and 50 ppm
under two different load conditions (4.75 and 24.0 kW), associated with two different motor rotating speeds.
(1,770 and 2,420 rpm). Samples were taken with an isokinetic sampling unit capable of separating PM
samples in three fractions (<2.5, 2.5-10, >10 microns).
Environmental sampling in a tunnel serving the Aburrá Valley region. Concentrations and samples of
PM2.5 in the FERNANDO GOMEZ MARTINEZ tunnel were taken during complete 24 hour periods, at
several times in 2010, in which there was certainty about the sulphur content of the diesel fuel used by the
vehicles in the Aburrá Valley region. In this way the said three types of diesel fuel, with S content 2,100, 500
and 50 ppm could be correlated with the samples.
Environmental sampling in two sites in the Aburrá Valley region. For these samples, two (2) PQ-200,
BGI Instrument, (equipped with Teflon and Quartz filters) were placed two (2) zones of the Aburrá Valley
[Instituto Politecnico Jaime Isaza Cadavid (Poli) and Universidad Nacional- Facultad de Minas (Unal)] in six
(6) alternate measurement campaigns, with two simultaneous ones for both sites. Samples were taken during
complete 24 hour periods, in such a way that they could be correlated with the ongoing changes in the diesel
fuel S content (2,100, 500 and 50 ppm respectively). A total of 50 samples were collected in each area.

3. In the three studies, samples were taken with Tefón and Quartz filters and subjected to chemical analysis in
Laboratory Alpha in Colombia for metallic oxides and in the DRI (Reno, Nevada) for ions and carbonaceous
species (EC and OC). Analytical techniques used were Spectrofluorometry, 3D Polarized Energy Dispersive
X-Ray Fluorescence (Epsilon Model 5), for the determination of mineral oxides; ion chromatography
(Dionex Model 3000) for the quantification of anions and cations; and the IMPROVE-A Thermal Method
Protocol for the determination of organic carbon and elemental carbon.
3. RESULTS AND DISCUSSION
Table 3 shows the major results obtained in the laboratory bench motor study. The results are expressed as
specific emission factors.
Table 3. PM 2.5 specific emissions in diesel laboratory bench motor study
Sulfur in diesel fuel, ppm 50 500 2,100 50 500 2,100
Motor rotational speed, rpm 1,770 1,770 1,770 2,420 2,420 2,420
Motor mechanical power, kW 4.69 4.76 4.75 24.1 23.9 23.9
PM 2.5 emissions, kg/ton fuel 3.76 5.50 8.76 0.81 0.78 2.55
OC, kg/ton fuel 2.234 3.303 5.239 0.275 0.218 0.526
EC, kg/ton fuel 0.060 0.068 0.175 0.293 0.328 0.949
Sulfates, kg/ton fuel 0.0396 0.1166 0.1638 0.0130 0.0203 0.6244
Nitrates, kg/ton fuel 0.0468 0.0554 0.0383 0.0046 0.0036 0.0032
Sodium, kg/ton fuel 0.0479 0.0549 0.0501 0.0043 0.0068 0.0292
OC, % of PM 2.5 59.42 60.01 59.83 34.09 28.16 20.63
EC, % of PM 2.5 1.60 1.24 1.99 36.35 42.31 37.22
Sulfates, % of PM 2.5 1.05 2.12 1.87 1.62 2.61 24.49
Figures 2 and 3 show that PM 2.5 and sulfate in PM 2.5 emissions diminish with lower S in diesel fuel. The
effect depends on motor load.
10 0.8
Sulfates in PM 2.5
PM 2.5, kg/ton fuel.
2
8
2
R = 0.98 0.6 R = 0.96
kg/ton fuel.
6 0.4 2
R = 0.81
4 2 0.2
R = 0.95
0.0
2
0 0 1,000 2,000 3,000
0 800 1,600 2,400 S in diesel, ppm
S in diesel, ppm
PM 2.5 kg/ton fuel at 4.75 kW, average = 6.01 S ulfates kg/ton fuel at 4.75 kW, average = 0.11
PM 2.5 kg/ton fuel at 24 kW, average = 1.38 S ulfates kg/ton fuel at 24 kW, average = 0.22
Figure 2. Specific PM2.5 emissions and S in fuel Figure 3. Sulfates in PM2.5 emissions and S in fuel
Table 4 shows some major results obtained in the 5.00
tunnel study. Figure 4 shows a clear diminution of
4.00
% of PM 2.5 .
sulfate salts in the PM 2.5 with the lowering of the
sulfur in the diesel fuel. 3.00
2.00
Table 4 major results in study in tunnel
1.00
S in diesel fuel, ppm 2,100 500 50 0.00
PM 2.5 microgr./m3 225 420 249 0 800 1,600 2,400
Vehicles per hour 268 389 361 S in diesel, ppm
OC in PM 2.5 , % 23.8 22.7 25.8 S ulfates Amonium Ions, total
EC in PM 2.5 , % 56.3 59.5 55.5
Sulfates in PM2.5 , % 2.10 1.23 0.50 Figure 4. Soluble salts in PM2.5 in tunnel

4. Table 5 shows the results of the study done in the two sites in the city during the ongoing changes in the
diesel fuel composition.
Table 5. PM2.5 concentrations in stations in the studied region, micrograms/Nm3 and PM2.5
chemical composition (average % +/- 1.5 standard deviations) during changes in diesel S content
Station Poli Unal Poli Unal Poli Unal
S in fuel, ppm 2,100 2,100 500 500 50 50
PM 2.5, micrg/m3 32.7+/-17.4 27.6+/-6.9 26.6+/-22.3 31.4+/-13.6 27.9+/-11.4 32.8+/-12.8
OC, % 25.14+/-4.4 20.7+/-4.3 27.6+/-6.3 22.6+/-5.8 27.5+/-4.8 23.4+/-5.0
EC, % 23.3+/-5.7 40.1+/-5.0 27.6+/-10.4 44.2+/-9.3 25.9+/-6.3 44.7+/-6.2
Sulfates, % 16.26+/-3.4 12.66+/-2.6 11.69+/-7.2 7.44+/-3.7 11.25+/-3.3 7.14+/-1.8
Nitrates, % 0.62+/-0.21 0.35+/-0.11 0.56+/-0.51 0.45+/-0.48 0.55+/-0.32 0.57+/-0.75
Sodium, % 1.92+/-0.67 1.21+/-0.35 1.94+/-1.31 1.03+/-0.77 1.77+/-0.78 0.79+/-0.55
Ammonium, % 4.68+/-1.71 4.01+/-1.38 2.11+/-2.4 2.07+/-1.77 2.86+/-1.3 2.15+/-1.57
SO3, % 1.45+/-1.22 1.09+/-0.29 1.01+/-0.77 1.09+/-1.63 1.49+/-1.16 0.80+/-0.38
SiO2, % 1.86+/-0.95 1.36+/-0.67 2.0+/-1.58 1.64+/-1.33 2.45+/-2.38 1.19+/-1.09
Fe2O3, % 0.99+/-0.79 0.64+/-0.45 1.54+/-0.99 1.16+/-0.85 1.9+/-0.89 1.01+/-0.49
Figures 5 to 8 show the PM 2.5 concentrations during the entire sampling campaign, including de previous
data taken in the Bello, Itagüi and San Antonio stations.
160 2100 30
Sulfates in PM2.5 % .
PM2.5 conc.
120
1400 20
S ppm
80
700 10
40
0 0 0
0 120 240 360 0 120 240 360
S ampling day, starting 2009/11/17
Day of sampling (starting 2009/11/17)
PM 2.5, micrograms/m3, av= 31.5 +/- 14.0
S in diesel, ppm Itagüi Bello S an Antonio Poli Unal
Figure 5. PM 2.5 and changes in S in diesel fuel Figure 7 Sulfates in PM 2.5 for the stations
160 30
PM 2.5 micrograms/m3 .
Sulfate in PM 2.5,% .
25
120 20
15
80
10
40 5
0
0 0 800 1600 2400
0 800 1600 2400 S in diesel ppm
S in diesel ppm Itagüi Bello S an Antonio Poli Unal
Figure 6. PM 2.5 for each diesel S content value Figure 8 Sulfates in PM 2.5 and S content in diesel
fuel
4. CONCLUSION
A clear link was established between diesel sulfur content and PM 2.5 compositions and concentrations, which
indicates the large influence of diesel fuel vehicles impact on the pollution situation in the region and the
importance of this sulfur diminution. The impact is quite clear on the chemical PM 2.5 compositions which
show a significant diminution of sulfates and ammonium salts. The impact on concentrations is detectable
but is affected by the operational conditions of diesel equipment, vehicle age and operational practices.

5. 5. REFERENCES
Arango,J. Calidad de los Combustibles en Colombia. 2008. ECOPETROL.
Geller,M., Ntziachristos, L,, Mamakos A., Zissis Samaras, D., Schmitz, J., Sioutas,C. Physicochemical and redox
characteristics of particulate matter (PM) emitted from gasoline and diesel passenger cars. 2006. Atmospheric
Environment. Vol 40. Issue 36, 6988-7004.
Gómez, M., Dawidowski, L., Posada, E., Correa, M., Saldarriaga, J., Chemical Composition of PM2.5 in three zones of the
Aburrá Valley, Colombia. 2011. Poster #702 presented at the A&WMA 2011 Annual Meeting, Orlando, USA.
Matti Maricq, M. Chemical characterization of particulate emissions from diesel engines: A review. 2007. Journal of
Aerosol Science, Vol 38, Issue 11, 1079-1118.
Toro M., Ramírez, J., Quiceno, R.,Zuluaga, C. Cálculo de la emisión vehicular de contaminantes atmosféricos en la
ciudad de Medellín mediante factores de emisión CORINAIR. 2001, Revista ACODAL, 191, 42-49