**3. Brazilian vehicular emissions and control program of emissions**

### **3.1. Light-duty vehicles emission controls**

content of that order. In 2006, the country's fuel blenders had to reduce ethanol content to 20% of its blended fuel because of ethanol shortages and returning to 25% soon after. In Brazil,

> Ethanol sold Gasoline sold Diesel sold Biodiesel sold

1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012

Year

m3 in 2013. Biodiesel started to be sold in 2008, and since then sales increased from

. In Brazil, the diesel composition has considerably changed in the

**Figure 2.** Fuel consumption in Brazil. Data from the Brazilian National Agency of Petroleum, Natural Gas and Biofuels [22]. The biodiesel consumption was calculated considering its minimum content in diesel: 2% in 2008-2009 and 5%

last years. Diesel sold in Brazil, known as type B (containing biodiesel), the minimum biodiesel content was set to be 2% (v/v, B2) in 2008, 5% (v/v, B5) in 2010, 7% (v/v, B7) in 2014, and 10% (v/v, B10) after January, 2015. Details of the new regulations and for non-road applications are

The growth in the production of hydrous ethanol-fueled vehicles during the 1980s was very high due to the creation of the Brazilian National Alcohol Program, when about 94% of the new passenger vehicles were fueled by this biofuel, as can be seen in Figure 3. On the other hand, between the years 1989 and 1990, the surplus of gasoline associated with other factors resulted in a change from national alcohol overproduction to a deficit production situation [24]. In 1990, a combination of bad climatic conditions together with a rise in the international price of sugar forced the Brazilian Government to import alcohol (including methanol) for the first time to meet the national demand. Consumers had serious difficulties in getting alcohol to fill the tanks of their cars. In that year the production of ethanol-powered vehicles dropped from about 47% to about 11% of new vehicles produced. Due to shortage of anhydrous ethanol in Brazil, it was introduced, on an emergency basis, the mixture ethanol-gasoline-methanol

During all periods shown in Figure 2, diesel sales increased 2.2 times, from 2.6 × 107 m3

in 2013 (Figure 2). During that same period, ethanol sold decreased from

between 1996 and 2009 and then

) and decreased to 1.2

in 1991

m3

gasoline volume sold was constant at around 2 × 107 m3

0

1x10<sup>7</sup>

m3

2x10<sup>7</sup>

3x10<sup>7</sup>

Fuel sold (m

3

)

4x10<sup>7</sup>

5x10<sup>7</sup>

6x10<sup>7</sup>

1996 to 2003, restarted to increase, which peaked in 2009 (at 1.6 × 107

increased to 4 × 107 m3

380 Biofuels - Status and Perspective

in 2013 [22].

× 106 m3

2010-2013.

to 5.8 × 107

m3 to 2.9 × 106

available at the ANP website [23].

0.9 × 106

To control vehicular emissions, the Brazilian Government created in 1986 the Brazilian Motor Vehicle Air Pollution Control Program (PROCONVE) [20]. Its main goal was the reduction of atmospheric contamination by setting emission standards for vehicles, inducing technological improvements of manufacturing processes, enforcing those vehicles and engines to meet emission limits in standardized tests using a reference fuel. PROCONVE's target for control‐ ling pollution from otto cycle LDV is based on the US Programs LEV (Low Emission Vehicle) and the California Air Resources Board (CARB) [25]. The compliance of requirements is assessed through protocols developed based on standardized dynamometer procedures and "reference fuels" trials. Furthermore, PROCONVE also imposes certification of prototypes and the statistical monitoring of vehicles in production (production trials). The PROCONVE program for LDV was performed at different phases that are described in Table 1.


**Table 1.** Phases during the implementation of Brazilian Motor Vehicle Air Pollution Control Program for light vehicles (PROCONVE-L) [20].

Figure 4 shows the evolution of the vehicular emission limits of CO, HC, NOx, and total aldehydes (RCHO) for LDV (Phases PROCONVE -L). As noted, the phases become increas‐ ingly restrictive. For instance, in PROCONVE (L-1) new vehicles had to emit no more than 24 g of CO per kilometer traveled; this value decreased to 12 g/km in phase 2 (L-2) and remained at 2 g/km between phases 3 and 5, a reduction of approximately 92% in the emission of this pollutant. Nitrogen oxides had a gradual reduction during PROCONVE phases. In phase 1 (L-1), vehicles could emit a maximum of 2 g/km. This value was reduced to 1.4 g/km at L-2 (reduction of 30%). In subsequent phases, the reductions ranged between 52% and 58%. In phase 5, the maximum emission allowed for NOx from new vehicles was 0.12 g/km. Volatile organic compounds such as HC and RCHO also had a very significant reduction in emissions. In phase 1, the maximum emission of HC was 2.1 g/km, whereas in phase 5 this value was 0.05 g/km, a reduction of 98%. Limits were imposed to RCHO only in phase 2, when the maximum emission allowed for RCHO was 0.15 g/km in phase 2 and decreased to 0.02 g/km in phase 5, a reduction of 87%.

ling pollution from otto cycle LDV is based on the US Programs LEV (Low Emission Vehicle) and the California Air Resources Board (CARB) [25]. The compliance of requirements is assessed through protocols developed based on standardized dynamometer procedures and "reference fuels" trials. Furthermore, PROCONVE also imposes certification of prototypes and the statistical monitoring of vehicles in production (production trials). The PROCONVE

> Characterized by elimination of the most polluting vehicles and improvement of vehicles under production. The control of evaporative emissions also had begun at this stage. The main technological innovations that occurred in this phase were recycling of exhaust gases to control NOx emissions; secondary air injection in the exhaust manifold to control CO and HC; and optimization of the ignition stage.

Adaptation of catalysts and fuel injection systems for use with a mixture of ethanol was performed. The main innovations in vehicles were the electronic injection, electronically assisted carburetors, and catalytic converters. In 1994, the control of noise from vehicles started.

Given the requirement to meet the limits established from January 1, 1997 (CONAMA Resolution No. 15/1995), there were highly significant reductions compared to previous limits, and the manufacturer / importer employed the best available technology for the formation of mixing and electronic engine control, e.g., the oxygen sensor.

Referring to the CONAMA Resolution No. 315/2002, the priority at this phase that began in 2005 was the reduction of emissions of HCs and NOx (ozone precursor compounds). To attend this phase, engines with new technologies such as the optimized combustion chamber, increase in pressure of the injection pump, and the electronic fuel injection were

The same emission limits of phase L-4 (CONAMA Resolution No. 315/2002) was applied at this phase. The priority in phase L-5 was to reduce emissions of HC and NOx. Analogous to the phase L-4, technological innovations were developed (optimization of combustion

chamber, increase in pressure of the injection pump, and the

improvement in the electronic fuel injection). At this phase there was a reduction of 31% in emissions of non-methane hydrocarbons (NMHC) for light vehicles. In addition, NOx emissions showed reduction of 48% and 42% for light vehicles and diesel-powered vehicles, respectively. Additionally, aldehyde emissions were reduced by approximately 67%

program for LDV was performed at different phases that are described in Table 1.

developed.

for the light-duty vehicles.

**Table 1.** Phases during the implementation of Brazilian Motor Vehicle Air Pollution Control Program for light vehicles

**Stage Year of implementation Description**

Phase 1 (L-1) 1988-1991

382 Biofuels - Status and Perspective

Phase 2 (L-2) 1992-1996

Phase 3 (L-3) 1997-2004

Phase 4 (L-4) 2005-2008

Phase 5 (L-5) 2009-2013

(PROCONVE-L) [20].

 Figure 4 Evolution of the emission limits **Figure 4.** Evolution of the emission limits permit of CO, HC, NOx, and CHO for light vehicles during the phases of permit of CO, HC, NOx, and CHO for light vehicles during the phases of PROCONVE–L. PROCONVE-L.

### **3.2. Heavy-duty vehicles emissions control**

HDV have long been recognized as an important source of air pollution in urban areas [26, 27]. According to the São Paulo State Environmental Protection Agency [28], HDV are responsible for emitting into the atmosphere of Metropolitan Area of Sao Paulo 60.9% of all anthropogenic NOx, and 35.3% of all inhalable particulate matter (PM10) during the 2012 year. HDV diesel-powered also contribute to emissions of fine particulate matter (PM2.5), with black carbon (BC) as the main constituent. Emissions of CO and VOC, mainly aldehydes, also contribute to the air pollution from diesel exhaust [29, 30]. Efforts to reduce the emission of pollutants by HDV were delayed in Brazil. PROCONVE regulations for HDV began in 1990, but during phases 1 and 2 the limits for gaseous emission (P-1 phase) and PM (P-2 phase) were not legally required. The PROCONVE phases for controlling HDV emissions (Phases "P") are presented in Table 2 (CONAMA Resolution No. 18/86 [20]).


**Table 2.** Phases for the implementation of Brazilian Motor Vehicle Air Pollution Control Program for heavy vehicles (PROCONVE-P) [20].

Figure 5 shows the evolution of the emission limits of CO, HC, NOx, and PM for HDV (Phases PROCONVE-P). As can be seen, the phases become increasingly restrictive. In phase P-1, HDV could emit a maximum of 14 g/km of CO, a value that decreased during the following phases, and in phase P-5 was 2.1 g/km, a reduction of approximately 85% in the emission of CO. Reduction of NOx started from 18 g/km in phase P-1 to 5 g/km in phase P-5 (reduction of 72%). The maximum emission of HC was 3.5 g/km in phase P-1, whereas in phase 5 this value decreased to 0.66 g/km, (reduction of 81%). Emissions of PM had regulatory limits, started only in phase P-2; in this phase, new HDV had to emit less than 0.6 g/km. This value decreased, and in the phase P-6, it was 0.02 g/km, which represents a reduction of 97% from the initial phase of PROCONVE for HDV.

**3.2. Heavy-duty vehicles emissions control**

384 Biofuels - Status and Perspective

Phase P-1 and P-2 1990-1993

Phase P-3 1994-1997

Phase P-4 1998-2002

Phase P-6 2009-2011

(PROCONVE-P) [20].

presented in Table 2 (CONAMA Resolution No. 18/86 [20]).

**Stage Year of implementation Description**

phase.

**Table 2.** Phases for the implementation of Brazilian Motor Vehicle Air Pollution Control Program for heavy vehicles

Figure 5 shows the evolution of the emission limits of CO, HC, NOx, and PM for HDV (Phases PROCONVE-P). As can be seen, the phases become increasingly restrictive. In phase P-1, HDV could emit a maximum of 14 g/km of CO, a value that decreased during the following phases, and in phase P-5 was 2.1 g/km, a reduction of approximately 85% in the emission of CO. Reduction of NOx started from 18 g/km in phase P-1 to 5 g/km in phase P-5 (reduction of 72%). The maximum emission of HC was 3.5 g/km in phase P-1, whereas in phase 5 this value decreased to 0.66 g/km, (reduction of 81%). Emissions of PM had regulatory limits, started only

matter (PM), NOx, and HC.

Phase P-5 2003-2008 Aimed to reduce emissions of PM, NOx, and HC.

HDV have long been recognized as an important source of air pollution in urban areas [26, 27]. According to the São Paulo State Environmental Protection Agency [28], HDV are responsible for emitting into the atmosphere of Metropolitan Area of Sao Paulo 60.9% of all anthropogenic NOx, and 35.3% of all inhalable particulate matter (PM10) during the 2012 year. HDV diesel-powered also contribute to emissions of fine particulate matter (PM2.5), with black carbon (BC) as the main constituent. Emissions of CO and VOC, mainly aldehydes, also contribute to the air pollution from diesel exhaust [29, 30]. Efforts to reduce the emission of pollutants by HDV were delayed in Brazil. PROCONVE regulations for HDV began in 1990, but during phases 1 and 2 the limits for gaseous emission (P-1 phase) and PM (P-2 phase) were not legally required. The PROCONVE phases for controlling HDV emissions (Phases "P") are

> In 1990, engines with lower emission levels than that required in 1993 (the year that began the emission control for vehicles of this type with the introduction of phases P-1 and P-2) were produced. During this period, the limits for gaseous emission (P-1 phase) and

The development of new engine models aimed at the reduction of fuel consumption, to increase power and to reduce emissions of NOx by adopting the intercooler and turbo engines. This phase promoted a drastic reduction of CO (43%) and HC (50%).

Emission limits have become even more restrictive than the P-3

In January 2009, the phase P-6 started, according to CONAMA Resolution No. 315/2002. The main objective of this phase, as well as the P-5 phase, was the reduction of emissions of particulate

particulate matter (P-2 phase) were not legally required.

**Figure 5.** Evolution of the emission limits of CO, NOx, HC, and PM for HDV during the phases of PROCONVE-P.

Although established by the CONAMA Resolution 315/2002 [20], P-6 phase was not imple‐ mented on time due to delays in the specification of fuel (diesel) to be sold in Brazil. This fact caused delays in production of diesel with lower sulfur content and delays on the production of technological innovation engines of new vehicles. Reductions in the concentration of sulfur in diesel constituted a precondition for meeting the limits in P-6 phase, since the formation of sulfur compounds in combustion contributes to the so-called "poisoning" of the catalyst, not providing good operation, even in reducing emissions of NOx and HC.

In 2005, diesel S-2000 (2000 ppm of sulfur as a maximum limit) started to be sold in Brazil while S-500 (500 ppm of sulfur content in diesel) started to be sold only in the metropolitan areas. Reducing sulfur content in diesel from 13,000 ppm to 500 ppm provided a significant reduction of sulfur emissions in recent years. According to Resolution 315/2002 [20], which was not attended on schedule, after January 1, 2009, the P-6 phase should have started with S-500 diesel been distributed in Brazil and diesel S-50 in metropolitan areas. However, this phase was not implemented on schedule, so CONAMA established in November 2008, through Resolution No. 403 [20], a new phase (P-7) for HDV, which has stricter emission limits. Low sulfur content fuel legislation is being established in Brazil as a result of new legislation (P-7), which requires exhaust gas recirculation (EGR) or selective catalytic reduction (SCR) aftertreatment systems implementation in new HDV, starting in January 1, 2012, which is equivalent to meet the Euro V European emission standards for heavy-duty diesel engines. This phase (P-7), started on January 1, 2012, and enabled the availability and commercialization of a diesel fuel with content of 10 ppm sulfur (S-10). The automobile and fuel industries are required until 2016 to adapt to new technical standards, providing diesel engines and fuels to Brazilian markets following patterns already adopted in Europe, where diesel vehicles emit sulfur content up to 200 times smaller than is released by the Brazilian buses and trucks.

### **3.3. Emissions of gaseous pollutants from vehicles in Brazil**

The effects of adding different blends of hydrous ethanol to a reference gasoline on flex fuel engine was evaluated in a study developed by de Melo et al. [31]. The results showed that, in general, CO emissions were reduced with hydrous ethanol addition due to the higher oxygen content of the ethanol contributing to oxidation into CO2. Total hydrocarbons emissions were also reduced, while aldehydes and unburned ethanol increased with hydrous ethanol addition. Emissions of NOx presented a complex behavior, without a particular defined trend. At 3875 rpm, knocking occurrence limited spark timing advance leading to lower NOx emissions when using gasoline E25 (without hydrous addition) and fuel blend content of 30% hydrous ethanol. With hydrous ethanol addition, there was a trend of NOx reduction at lower speeds (1500 and 2250 rpm), while for high speed (4500 rpm), there was a trend of NOx increase.

A comparative study was carried out of pollutant emissions produced by a mid-size sedan powered by 1.4-L spark ignition engine on a chassis dynamometer operating with three different fuels. Commercial gasoline with 22% of ethanol (E22, gasohol), compressed natural gas (CNG), and hydrous ethanol showed that in the cold start tests the E22 produced the lowest CO and HC emissions, while CNG produced the lowest NOx emissions [32]. Considering the full test cycle, CNG emitted the lowest CO, NOx, and CO2 concentrations, and the lowest fuel consumption. Gasohol (E22) presented the lowest emission levels of HC and CH4. Hydrous ethanol showed the highest fuel consumption and higher pollutant emission levels than the other fuels, except for CO2, which was higher than CNG and lower than gasohol.

Randazzo et al. [33] investigated the effects of use of diesel/biodiesel blends with concentra‐ tions of 3% (B3), 5% (B5), 10% (B10), and 20% (B20) on a passenger vehicle exhaust emissions, and the results showed that increasing biodiesel concentration in the fuel blend increases CO2 and NOx emissions, while CO, HC, and PM emissions were reduced. Additionally, the work evaluated the effects of anhydrous ethanol as an additive to B20 fuel blend with con‐ centrations of 2% (B20E2) and 5% (B20E5). The results showed that the addition of anhydrous ethanol to B20 fuel blend can be a strategy to control NOx exhaust. However, the authors concluded that it may require fuel injection modifications, since in this condition increases in CO, HC, and PM emissions were observed.

been distributed in Brazil and diesel S-50 in metropolitan areas. However, this phase was not implemented on schedule, so CONAMA established in November 2008, through Resolution No. 403 [20], a new phase (P-7) for HDV, which has stricter emission limits. Low sulfur content fuel legislation is being established in Brazil as a result of new legislation (P-7), which requires exhaust gas recirculation (EGR) or selective catalytic reduction (SCR) aftertreatment systems implementation in new HDV, starting in January 1, 2012, which is equivalent to meet the Euro V European emission standards for heavy-duty diesel engines. This phase (P-7), started on January 1, 2012, and enabled the availability and commercialization of a diesel fuel with content of 10 ppm sulfur (S-10). The automobile and fuel industries are required until 2016 to adapt to new technical standards, providing diesel engines and fuels to Brazilian markets following patterns already adopted in Europe, where diesel vehicles emit sulfur content up to

The effects of adding different blends of hydrous ethanol to a reference gasoline on flex fuel engine was evaluated in a study developed by de Melo et al. [31]. The results showed that, in general, CO emissions were reduced with hydrous ethanol addition due to the higher oxygen content of the ethanol contributing to oxidation into CO2. Total hydrocarbons emissions were also reduced, while aldehydes and unburned ethanol increased with hydrous ethanol addition. Emissions of NOx presented a complex behavior, without a particular defined trend. At 3875 rpm, knocking occurrence limited spark timing advance leading to lower NOx emissions when using gasoline E25 (without hydrous addition) and fuel blend content of 30% hydrous ethanol. With hydrous ethanol addition, there was a trend of NOx reduction at lower speeds (1500 and 2250 rpm), while for high speed (4500 rpm), there was a trend of NOx

A comparative study was carried out of pollutant emissions produced by a mid-size sedan powered by 1.4-L spark ignition engine on a chassis dynamometer operating with three different fuels. Commercial gasoline with 22% of ethanol (E22, gasohol), compressed natural gas (CNG), and hydrous ethanol showed that in the cold start tests the E22 produced the lowest CO and HC emissions, while CNG produced the lowest NOx emissions [32]. Considering the full test cycle, CNG emitted the lowest CO, NOx, and CO2 concentrations, and the lowest fuel consumption. Gasohol (E22) presented the lowest emission levels of HC and CH4. Hydrous ethanol showed the highest fuel consumption and higher pollutant emission levels than the

Randazzo et al. [33] investigated the effects of use of diesel/biodiesel blends with concentra‐ tions of 3% (B3), 5% (B5), 10% (B10), and 20% (B20) on a passenger vehicle exhaust emissions, and the results showed that increasing biodiesel concentration in the fuel blend increases CO2 and NOx emissions, while CO, HC, and PM emissions were reduced. Additionally, the work evaluated the effects of anhydrous ethanol as an additive to B20 fuel blend with con‐ centrations of 2% (B20E2) and 5% (B20E5). The results showed that the addition of anhydrous ethanol to B20 fuel blend can be a strategy to control NOx exhaust. However, the authors

other fuels, except for CO2, which was higher than CNG and lower than gasohol.

200 times smaller than is released by the Brazilian buses and trucks.

**3.3. Emissions of gaseous pollutants from vehicles in Brazil**

increase.

386 Biofuels - Status and Perspective

Pérez-Martinez et al. [34] showed that emissions factors for on-road LDV in the MASP in 2011 were 5.8 and 0.3 g/km, for CO and NOx, respectively. The values estimated in this study showed a significant reduction when comparing the values of emissions factors calculated in the experiment conducted in 2004 [35]. The values estimated in 2004 were 14.6 and 1.6 g/km, for CO and NOx, respectively. The reduction ratio was 2.5 times for CO and 3.2 for NOx. The authors attributed this fact to increased use of modern three-way catalysts using platinum and rhodium surfaces, which changes the nitrogen oxides back to nitrogen and elemental oxygen and complete the oxidation of CO to CO2 [36]. In addition, there was the increased number of vehicles able to burn ethanol. In 2011, from the cars running in the MASP, about 55 % gasohol, 4 % burned hydrous ethanol, and 38 % were capable of burning both gasohol and hydrous ethanol (flex-fuel vehicles), while in 2004 about 69.5% of vehicles burned gasohol and 14.5% of the fleet burned hydrous ethanol. Regarding HDV, in 2011 the emissions factors estimated by Pérez-Martinez et al. [34] were 3.6 and 9.2 g/km, for CO and NOx, respectively, which represents a reduction of 5.7 and 2.4, for CO and NOx, in comparison with the data obtained for HDV running in 2004 in the MASP. In 2011, HDV burned a mixture containing 5% biodiesel, which may contributed to reduction in CO emissions [37], while minor decrease in emissions of NOx pollutant reported in the study may be associated with the use of biodiesel.

Guarieiro et al. [38] evaluated the exhaust emissions of a diesel engine running on biodiesel and operated by a steady-state dynamometer which provided a composition profile of the carbonyl compound emissions from exhaust of pure diesel (B0), pure biodiesel (B100), and biodiesel-diesel mixtures (B2, B5, B10, B20, B50, B75). This work showed that the mean concentration sum of total carbonyl compounds emission were 20.5 ppmv for B0 and 15.7 ppmv for B100, while for fuel blends the total concentration of carbonyl compounds were 21.4, 22.5, 20.4, 14.2, 11.4, and 14.7 ppmv, respectively, for B2, B5, B10, B20, B50, and B75. The study showed that major contributors to the total carbonyl compounds were formaldehyde and acetaldehyde, and that except for formaldehyde and acrolein, all carbonyl compounds showed a clear trend of reduction in the emissions from B2 to B100 (40% reduction, on average). The lowest total carbonyl emission factors were found when B50 was used, 2271 pg/g of fuel burned, while the individual emission factors determined (pg/g of fuel burned) were 539.7 (formaldehyde), 1411 (acetaldehyde), 30.83 (acrolein), and 310.7 (propionaldehyde).

Carbonyl compounds were measured in vapor-phase samples in a study developed in a Bus Station impacted by HDV fuelled with diesel/biodiesel fuel blend (B5) in Salvador, Bahia, Brazil, in 2012 [39]. Among them, formaldehyde, acetaldehyde, and propanone were the major quantified compounds, ranging from 28.4 to 287.3 ppbv (formaldehyde), 24.9 to 171.3 ppbv (acetaldehyde), and 5.8 to 72.3 (propanone). The data obtained in this site were compared to formaldehyde and acetaldehyde concentrations found in other sites impact‐ ed by HDV fuelled with pure diesel and diesel/biodiesel blends. The authors reported that the addition of concentrations higher than 3% of biodiesel to diesel showed an improve‐ ment in the carbonyl concentration profile at these places with high flow of HDV, and that the use of these biofuels revealed profiles similar to those found for sites less impacted by these vehicles. Higher concentrations of these carbonyls were observed in the current study compared to the results obtained in the same bus station in 1997 [40]. The average formaldehyde and acetaldehyde concentrations increased approximately 1.5 and 7 times, respectively, between the two observation periods. The authors suggested that these significant differences found between the two sampling periods can be explained by the increase of the vehicle fleet currently circulating in the Lapa Bus Station. While in 1997 the vehicular fleet at the Lapa bus station was 150 buses per hour, in 2010 it was over 330 buses per hour. In this manner, an increase of the vehicle fleet circulating in Lapa station can reflect a rise of both formaldehyde and acetaldehyde emission concentrations at that site. Other factors suggested by the authors was that the reason for the observed increase of carbonyl compounds concentration at this site was related to changes of the fuels used in vehicles. In 1997, buses were fuelled with pure diesel and in 2012 they were fuelled with B5 fuel blend. The results of an experimental campaign at a central bus station in Londri‐ na, Brazil, where only pure diesel powered vehicles circulated showed that the formalde‐ hyde concentrations were significantly higher than acetaldehyde [41]. The formaldehyde levels ranged from 6.17 to 10.43 ppbv with an average of 7.94 ppbv, while acetaldehyde presented levels in the interval of 0.49 to 2.12 ppbv with an average of 1.26 ppbv. The formaldehyde concentration was six times higher than the acetaldehyde concentration.

Nogueira et al. [42] determined on-road emissions of carbonyls from Brazil's current vehicle fleet based on two experimental campaigns conducted in traffic tunnels located in the MASP. Among carbonyl species, formaldehyde and acetaldehyde were the most abundant com‐ pounds found during all sampling time intervals. The higher carbonyl emissions were associated with HDV, which were fueled with a blend of regular diesel and 5% biodiesel from soy. LDV were responsible for high emissions of acetaldehyde, since in Brazil this type of vehicle burns a mixture of 75% (v/v) gasoline and 25% ethanol (gasohol), or hydrous ethanol. Brazilian LDVs reported emission of 5.7 mg/km and 7.4 mg/km for formaldehyde and acetaldehyde, respectively. When compared with data from LDV in the California, these values are 352% and 263% higher than that emitted by vehicles running on E10 (gasoline with 10% ethanol). The HDV average emission factor for formaldehyde and acetaldehyde was 28 and 20 mg/km, respectively, indicating that there was a reduction in the HDV emission of form‐ aldehyde (42%) and acetaldehyde (58%) when comparing with the values obtained in an experiment conducted in the MASP in 2004 [35]. HDV running in 2011 in the MASP with diesel + 5% biodiesel showed formaldehyde emissions 33% higher than HDV running in California in 2010 with regular diesel [43].

Figure 6 shows the aldehyde emissions in milligrams per kilometer traveled by new vehicles sold in Brazil, together with the limits specified in each phase of the PROCONVE. As it can be seen, significant reductions in emissions occurred due to the evolution of pollution control public policies. Prior to 1992 (before and during phase 1 of the PROCONVE), no limits existed regarding aldehyde emissions. During that period, vehicles running on ethanol emitted about 0.13 g of total aldehyde (RCHO) per kilometer, about three times higher than vehicles running on gasohol. In phase 2 of the PROCONVE, which started in 1992, when the emission limit was initially 0.15 g of aldehyde per km traveled but later reduced to 0.03 g of aldehyde per km traveled by 1997 (the beginning of Phase 3). As observed, vehicles running on ethanol emit more total aldehydes than do vehicles running on gasohol and the quantity of aldehydes emitted by ethanol-powered vehicles is similar to that emitted by flex-fuel vehicles running on ethanol. However, the production of vehicles powered by ethanol only was discontinued in 2006, and there are therefore no longer any records of emissions for new vehicles. It is also noteworthy that flex-fuel vehicles manufactured in 2010 emitted an average of 0.007 g of aldehyde per km when new and using ethanol, which was about 65% less than their 2003 counterparts under the same conditions. The PROCONVE is currently in phase 6, and the limit for aldehyde emissions is 0.02 g per km traveled.

**Figure 6.** Total aldehydes (RCHO) emission factors from 1980 to 2010 for Brazilian LDV running with gasohol and ethanol fuels, and the phases of the PROCONVE.

#### **3.4. Emissions of particulate matter from vehicles in Brazil**

these vehicles. Higher concentrations of these carbonyls were observed in the current study compared to the results obtained in the same bus station in 1997 [40]. The average formaldehyde and acetaldehyde concentrations increased approximately 1.5 and 7 times, respectively, between the two observation periods. The authors suggested that these significant differences found between the two sampling periods can be explained by the increase of the vehicle fleet currently circulating in the Lapa Bus Station. While in 1997 the vehicular fleet at the Lapa bus station was 150 buses per hour, in 2010 it was over 330 buses per hour. In this manner, an increase of the vehicle fleet circulating in Lapa station can reflect a rise of both formaldehyde and acetaldehyde emission concentrations at that site. Other factors suggested by the authors was that the reason for the observed increase of carbonyl compounds concentration at this site was related to changes of the fuels used in vehicles. In 1997, buses were fuelled with pure diesel and in 2012 they were fuelled with B5 fuel blend. The results of an experimental campaign at a central bus station in Londri‐ na, Brazil, where only pure diesel powered vehicles circulated showed that the formalde‐ hyde concentrations were significantly higher than acetaldehyde [41]. The formaldehyde levels ranged from 6.17 to 10.43 ppbv with an average of 7.94 ppbv, while acetaldehyde presented levels in the interval of 0.49 to 2.12 ppbv with an average of 1.26 ppbv. The formaldehyde concentration was six times higher than the acetaldehyde concentration.

Nogueira et al. [42] determined on-road emissions of carbonyls from Brazil's current vehicle fleet based on two experimental campaigns conducted in traffic tunnels located in the MASP. Among carbonyl species, formaldehyde and acetaldehyde were the most abundant com‐ pounds found during all sampling time intervals. The higher carbonyl emissions were associated with HDV, which were fueled with a blend of regular diesel and 5% biodiesel from soy. LDV were responsible for high emissions of acetaldehyde, since in Brazil this type of vehicle burns a mixture of 75% (v/v) gasoline and 25% ethanol (gasohol), or hydrous ethanol. Brazilian LDVs reported emission of 5.7 mg/km and 7.4 mg/km for formaldehyde and acetaldehyde, respectively. When compared with data from LDV in the California, these values are 352% and 263% higher than that emitted by vehicles running on E10 (gasoline with 10% ethanol). The HDV average emission factor for formaldehyde and acetaldehyde was 28 and 20 mg/km, respectively, indicating that there was a reduction in the HDV emission of form‐ aldehyde (42%) and acetaldehyde (58%) when comparing with the values obtained in an experiment conducted in the MASP in 2004 [35]. HDV running in 2011 in the MASP with diesel + 5% biodiesel showed formaldehyde emissions 33% higher than HDV running in California

Figure 6 shows the aldehyde emissions in milligrams per kilometer traveled by new vehicles sold in Brazil, together with the limits specified in each phase of the PROCONVE. As it can be seen, significant reductions in emissions occurred due to the evolution of pollution control public policies. Prior to 1992 (before and during phase 1 of the PROCONVE), no limits existed regarding aldehyde emissions. During that period, vehicles running on ethanol emitted about 0.13 g of total aldehyde (RCHO) per kilometer, about three times higher than vehicles running on gasohol. In phase 2 of the PROCONVE, which started in 1992, when the emission limit was initially 0.15 g of aldehyde per km traveled but later reduced to 0.03 g of aldehyde per km

in 2010 with regular diesel [43].

388 Biofuels - Status and Perspective

Atmospheric aerosol or particulate matter (PM) is a complex mixture of extremely small particles and liquid droplets, presenting also a complex chemical composition [44, 45]. The atmospheric PM is a stable suspension of liquid or solid particles with an aerodynamic diameter lower than 100 µm. Actually, the classification of PM size is very important due to its effects on human health and/or its direct and indirect effects in the environment and climate. The concentrations, size, and number distributions of particles are affected by physical and chemical processes or kinds of sources (natural or anthropogenic, and secondary atmospheric aerosol production). The inhalable particles have aerodynamic diameter equal or lower than 10 µm (PM10), being divided into fine (PM2.5) and coarse (PM2.5-10) particles [44, 45]. It is important to emphasize that to control both the PM emissions by burning fuels and air quality, the legislation considers the mass concentration (µg/m3 ) for a given particle size range (PM2.5 and PM10), without any relationship with the chemical composition. This parameter is valid for the national air quality standards, and also for the WHO guidelines [46]. For PM, even though the mass concentration, the most important parameter in legislation, the chemical composition measurements can contribute to better knowledge not only to the emission processes but also to the effects on health and environment. The PM is a complex mix of different elements and compounds both inorganic and organic/carbonaceous, which includes the ions (sulfate, nitrate, chloride, ammonium, sodium, potassium, calcium, and magnesium), the trace elements and/or metals (Pb, Zn, Ni, Cu, V, Cr, Cd, Al, P, S, Si, Ti, Ca, Fe, and others), elemental carbon (and black carbon) and organic compounds from simple hydrocarbons to oxygenated, aromatics, and polycyclic aromatic hydrocarbons. The fraction of these different compounds in the PM mass is due to sources and/or of the physical-chemical processes during the particles' life cycles [44, 45]. The heavy metals in the form of free elements are non-toxic. However, they are dangerous in their cationic form and when bound to short carbon chains. The metal ions form complexes with a large amount of binders and influence the biological functions, affecting the normal development of living beings' tissues and their adequate functioning [47]. Heavy metals, also referred to as trace elements, are an important fraction of the PM because they represent a risk to human health. Trace metals in airborne PM were considered to represent a health hazard since they can be absorbed into human lung tissues during breathing. Although many of these metals are constituents of tissues, their toxic effects are known even at low levels. Inorganic ions, as well as other PM constituents, result from fuel burning. In addition, these pollutants affect climate change, contribute to the acidification of aerosol, changing its conductivity [48]. Therefore, it is extremely important to have a qualita‐ tive and quantitative understanding of the PM composition and the contribution of fuel burning as well as the role of biofuel addition.

The speciation of organic compounds is still a major challenge, being an important advance‐ ment the differentiation between organic carbon and elemental carbon (or graphitic). Special attention is necessary for black carbon (BC) and elemental carbon (EC) measurements and reports [49]. BC is an important component of the PM, produced by incomplete combustion processes (fossil fuels, biofuels, and biomass), having a graphite-like microstructure, being strongly absorbent of visible light, refractory and insoluble in water and in organic solvents including methanol and acetone [49]. As BC is the most strongly light absorbing component of PM, it absorbs both incoming and outgoing radiation of all wavelengths, which contributes to warming of the atmosphere and darkening of the surface. It is, therefore, a pollutant that has important climatic influences [50].

One of the most important groups of organic compounds is the polycyclic aromatic hydro‐ carbons (PAH) that are present in the gas- and particle-phase in ambient air as well as other environmental compartments. These organic compounds have known mutagenic and carcinogenic properties. Due to this harmful effect of some PAH to humans, the US EPA shows them in its priority pollutants list, being some PAH structures shown in Figure 7. The lipo‐ philicity, environmental persistence, and genotoxicity increase with heavier molecular weight from 4 to 6 aromatic rings [51-54]. PAHs are formed by the pyrolysis and incomplete combus‐ tion of organic compounds [55, 56]. A major source of this class of pollutants in large urbanized centers is the vehicular emission. Fuel burning produces, among other pollutants, measurable concentrations of PAH, depending on the characteristics of the fuel.

Bioethanol and Biodiesel as Vehicular Fuels in Brazil — Assessment of Atmospheric Impacts from the Long Period... http://dx.doi.org/10.5772/60944 391

**Figure 7.** Structures and nomenclatures of the 16 PAHs on the EPA priority pollutant list.

though the mass concentration, the most important parameter in legislation, the chemical composition measurements can contribute to better knowledge not only to the emission processes but also to the effects on health and environment. The PM is a complex mix of different elements and compounds both inorganic and organic/carbonaceous, which includes the ions (sulfate, nitrate, chloride, ammonium, sodium, potassium, calcium, and magnesium), the trace elements and/or metals (Pb, Zn, Ni, Cu, V, Cr, Cd, Al, P, S, Si, Ti, Ca, Fe, and others), elemental carbon (and black carbon) and organic compounds from simple hydrocarbons to oxygenated, aromatics, and polycyclic aromatic hydrocarbons. The fraction of these different compounds in the PM mass is due to sources and/or of the physical-chemical processes during the particles' life cycles [44, 45]. The heavy metals in the form of free elements are non-toxic. However, they are dangerous in their cationic form and when bound to short carbon chains. The metal ions form complexes with a large amount of binders and influence the biological functions, affecting the normal development of living beings' tissues and their adequate functioning [47]. Heavy metals, also referred to as trace elements, are an important fraction of the PM because they represent a risk to human health. Trace metals in airborne PM were considered to represent a health hazard since they can be absorbed into human lung tissues during breathing. Although many of these metals are constituents of tissues, their toxic effects are known even at low levels. Inorganic ions, as well as other PM constituents, result from fuel burning. In addition, these pollutants affect climate change, contribute to the acidification of aerosol, changing its conductivity [48]. Therefore, it is extremely important to have a qualita‐ tive and quantitative understanding of the PM composition and the contribution of fuel

The speciation of organic compounds is still a major challenge, being an important advance‐ ment the differentiation between organic carbon and elemental carbon (or graphitic). Special attention is necessary for black carbon (BC) and elemental carbon (EC) measurements and reports [49]. BC is an important component of the PM, produced by incomplete combustion processes (fossil fuels, biofuels, and biomass), having a graphite-like microstructure, being strongly absorbent of visible light, refractory and insoluble in water and in organic solvents including methanol and acetone [49]. As BC is the most strongly light absorbing component of PM, it absorbs both incoming and outgoing radiation of all wavelengths, which contributes to warming of the atmosphere and darkening of the surface. It is, therefore, a pollutant that

One of the most important groups of organic compounds is the polycyclic aromatic hydro‐ carbons (PAH) that are present in the gas- and particle-phase in ambient air as well as other environmental compartments. These organic compounds have known mutagenic and carcinogenic properties. Due to this harmful effect of some PAH to humans, the US EPA shows them in its priority pollutants list, being some PAH structures shown in Figure 7. The lipo‐ philicity, environmental persistence, and genotoxicity increase with heavier molecular weight from 4 to 6 aromatic rings [51-54]. PAHs are formed by the pyrolysis and incomplete combus‐ tion of organic compounds [55, 56]. A major source of this class of pollutants in large urbanized centers is the vehicular emission. Fuel burning produces, among other pollutants, measurable

concentrations of PAH, depending on the characteristics of the fuel.

burning as well as the role of biofuel addition.

390 Biofuels - Status and Perspective

has important climatic influences [50].

The analytical techniques used for determination and quantification of the PM components, not only for emissions but also for atmospheric measurements, are shown in Table 3. These techniques include continuous aerosol sampling and analysis systems or analysis methods that are commonly applied to aerosol filter samples. The details of the analytical methods, advantages, and disadvantages are available in an important review about PM sampling and measurements [57]. Another important discussion involves the question of the appropriate‐ ness of sampling and analysis methods of PM for the purpose of adapting the requirements needed to establish emission and air quality standards. This discussion involves size-selective inlets (cyclonic flow, impactor, virtual impactor, and selective filtration), if the sampling is continuous or integrated in time (24 h standard), filters characteristics for only mass quantifi‐ cation or also for chemical composition (membranes of Teflon, polycarbonate, glass fiber, cellulose esters, or silver), plus the details regarding the flow measurement, flow control, and flow movers [58]. In the past decades, new techniques development enabled measurements of aerosol integral properties (total number concentration, cloud condensation nucleus concen‐ tration, optical coefficients, etc.), aerosol physical chemical properties (density, refractive index, equilibrium water content, etc.), measurements of aerosol size distributions, and measurements of size-resolved aerosol composition [59].

Emission quantifications (mass per kilometer traveled or mass per fuel mass burned) are calculated based on dynamometers (vehicles or motors) or tunnels experiments, being that the former corresponds an individual emission, while the latter represents the real fleet. Evalua‐ tion of influence of direct emissions on air pollutants concentrations from fuel burning by vehicles can be happened by experiments in special sites, like bus stations, close streets or avenues with heavy traffic, etc.


**Table 3.** Some analytical techniques for analysis of the main constituents of particle matter.

Tunnel experiments were performed in MASP in different times and even sampling in two tunnels, one with predominance of light-duty vehicles (LDV) that burn gasohol (75% gasoline + 25% anhydrous ethanol) and ethanol, and one that had LDV plus significant number of heavy-duty vehicles (HDV) that burn diesel and/or diesel + biodiesel [60]. Experiments during 2011 showed that LDV and HDV running in the Metropolitan Area of São Paulo has emitted less PM2.5 in recent years than in the past [34]. In 2004 [60], LDV emitted 92 mg of particles (PM2.5) per kilometer traveled, while in 2011 [34] this value decreased to 20 mg/km, a reduction of 4.6 times. Emissions from HDV decreased from 588 mg/km in 2004 to 277 mg/km in 2011, a reduction about 2 times. These data showed that LDV have a greater reduction in PM emissions, since in this period of study there was an improvement in the engine technology of LDV. Furthermore, in this period there was the introduction of flex fuel vehicles, and consequently the consumption of ethanol by vehicles has increase. On the other hand, HDV showed no major advances in engine technology, occurred only improves in the composition of diesel oil, for example, a reduction in sulfur content, and the addition of biodiesel to diesel (in 2011 vehicles circulated with 5% biodiesel).

tion of influence of direct emissions on air pollutants concentrations from fuel burning by vehicles can be happened by experiments in special sites, like bus stations, close streets or

Mass Gravimetric (filter weighing); beta attenuation monitor (BAM); tapered element

Black carbon Optical reflectometer (also called spotmeter and filter smokemeter); aethalometer;

(graphitic) Thermal/optical reflectance (TOR) or thermal/optical transmittance (TOT)

oscillation microbalance (TEOM ); quartz crystal microbalance (QCM)

multi-angle absorption photometer (MAAP); photoacoustic soot sensor (PASS)

X-ray fluorescence analysis (XRF); particle induced X-ray emission (PIXE); atomic absorption spectrometry (AA); emission spectrometry (EE); inductively coupled plasma-mass spectroscopy (ICP-MS); instrumental neutron activation analysis (INAA) anodic stripping voltammetry (ASV)

Ionic chromatography (IC)

Solvent extraction by Soxhlet techniques / cleanup by solid-phase extraction (SPE) follow analysis by high-performance liquid chromatography (HPLC) with various detectors (absorption, fluorescence, and mass spectrometry) / gas chromatography flame ionization detector (CGFID) / gas chromatography mass spectrometry (CGMS)

**Constituents of PM Usual analytical techniques**

**Table 3.** Some analytical techniques for analysis of the main constituents of particle matter.

Tunnel experiments were performed in MASP in different times and even sampling in two tunnels, one with predominance of light-duty vehicles (LDV) that burn gasohol (75% gasoline + 25% anhydrous ethanol) and ethanol, and one that had LDV plus significant number of heavy-duty vehicles (HDV) that burn diesel and/or diesel + biodiesel [60]. Experiments during 2011 showed that LDV and HDV running in the Metropolitan Area of São Paulo has emitted less PM2.5 in recent years than in the past [34]. In 2004 [60], LDV emitted 92 mg of particles (PM2.5) per kilometer traveled, while in 2011 [34] this value decreased to 20 mg/km, a reduction of 4.6 times. Emissions from HDV decreased from 588 mg/km in 2004 to 277 mg/km in 2011, a reduction about 2 times. These data showed that LDV have a greater reduction in PM emissions, since in this period of study there was an improvement in the engine technology of LDV. Furthermore, in this period there was the introduction of flex fuel vehicles, and consequently the consumption of ethanol by vehicles has increase. On the other hand, HDV showed no major advances in engine technology, occurred only improves in the composition

avenues with heavy traffic, etc.

392 Biofuels - Status and Perspective

Total carbon: organic vs. elemental

Elements and/or metals (Pb, Zn, Ni, Cu, V, Cr, Cd, Al, P, S, Si, Ti, Ca, Fe, Mg, Mn, K, As, Sb, Se, Co, In, Eu)

Inorganic ions

anions

Speciation of organics

) and/or carboxylate

(Cl- , NO3 - , SO42- , Na+ , K+ , Ca2+,

Mg2+, NH4 + Guarieiro et al. [61] evaluated the emission effects of biodiesel addition of 4% of soy biodiesel (B4), a biodiesel blend of 25% and 50% (B25 and B50) in diesel, and also pure biodiesel (B100). In this study, PM emissions were measured on a steady-state dynamometer in a test using a diesel engine at low load. Size-fractionated PM samples were collected using the NanoMOUDI impactor and analyzed for the 16 priority PAHs. In addition, PM2.5 samples were collected and analyzed for redox activity by DTT assay. PM was distributed in all sizes, while PAH size distributions were found at higher levels in the accumulation mode (30 nm < Dp < 2.5 µm). Total PAH emission factors for B4, B25, B50, and B100 were 237, 111, 182, and 319 ng/kg fuel burned, respectively. Individual PAH emission factors showed that PAH containing four or more rings (MW > 202) such as benzo(b)fluoranthene, benzo(a)anthracene, pyrene, and benzo[ghi]perilene were the main PAH emitted by the four studied fuels. The study showed that percentage reductions of individual PAH emission factors for the blend fuels in compar‐ ison with B4 were 37% and 22% for B25 and B50, respectively, and an increase around 31% for B100. This work also showed an increase in redox activity for B25, B50, and B100 when compared to B4. The results from this study suggest that emissions from pure waste cooking biodiesel may not be the better fuel choice in terms of PM, PAH, BaPE (corresponding carcinogenicity index) particle size distribution and emission factors as well as redox activity. However, B25 and B50 blends presented some improvements in terms of PM, PAH, BaPE size distribution, and redox activity of engine exhaust in comparison to B4. The results suggest that addition of low percentages biodiesel to diesel promotes benefits in both environmental and human health concerns [61].

Exhaust emissions of 17 polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofur‐ ans (PCDD/Fs) were compared from LDV fueled with gasohol and fueled with hydrous ethanol [62]. In this study were evaluated the influence of fuel type and quality, lubricant oil type, and use of fuel additives on the formation of these compounds. The results showed that emission factors of PCDD/Fs for the gasohol vehicle varied from undetected values to 0.068 pg international toxic equivalency/km traveled, whereas in the ethanol vehicle the observed variation ranged between 0.004 to 0.157 pg international toxic equivalency/km. The study also showed that use of fuel additive significantly diminished the emission of octachlorodibenzop-dioxin, in the gasohol-powered vehicle, whereas in the ethanol vehicle no significant associations were observed between the investigated variables and the emissions. The results of another study showed that vehicles running on gasohol emitted more of total PAH; the emission factors varied from 41.9 µg/km to 612 µg/km than vehicles running on ethanol from 11.7 µg/km to 27.4 µg/km [63]. The authors reported that in terms of benzo(a)pyrene toxicity equivalence, emission factors varied from 0.00984 µg TEQ/km to 4.61 µg TEQ/km for the gasohol vehicle and from 0.0117 µg TEQ/km to 0.0218 µg TEQ/km in the ethanol vehicle. The results also showed that the use of fuel additive for the gasohol vehicles cause a significant increase in the emission of naphthalene and phenanthrene, while the use of synthetic oil, instead of mineral oil, also contributed significantly to a decrease in the emission of naphtha‐ lene and fluorene. Regarding hydrous ethanol-powered vehicle, the same compounds were tested and showed no statistically significant influence on PAH emissions. Emissions of PAH from LDV running with ethanol or gasohol are lower than vehicles running with diesel, being that the diesel-powered vehicles showed emission about 200 times higher than vehicles running with ethanol [64]. Total PAH values from diesels ranged from 1.133 to 5.801 mg/km. Naphthalene, phenanthrene, fluoranthene, pyrene, and chrysene were detected in all test samples. Another study developed by da Silva et al. [65] evaluated the composition of inhalable particles and their trace metal content in LDV fueled with ethanol and gasohol. The results showed that the total emission factors ranged from 2.5 to 11.8 mg/km in the gasohol vehicle, and from 1.2 to 3 mg/km in the ethanol vehicle. The majority of particles emitted were in the fine fraction (PM2.5), in which Al, Si, Ca, and Fe corresponded to 80% of the total weight. The results also showed that PM10 emissions from the ethanol vehicle were about threefold lower than those of gasohol.

Correa and Arbilla [66] evaluated the emissions of mono- and polycyclic aromatic hydrocar‐ bons (MAHs and PAHs, respectively) from a six cylinder heavy-duty engine, typical of the urban buses of Brazilian fleet, fueled with pure diesel (D) and biodiesel blends (v/v) of 2% (B2), 5% (B5), and 20% (B20). The results showed the following average reduction of MAHs: 4.2% for B2 blend, 8.2% for B5 blend, and 21.1% for B20 blend. The average reductions for PAHs were 2.7% (B2), 6.3% (B5), and 17.2% (B20). However, some PAHs and MAHs emissions increased due to the biodiesel blends like phenanthrene, ethyl benzene, and trimethyl benzenes.

In order to characterize current concentrations of PM2.5 from LDV and HDV in the MASP, Brazil, measurements of physical and chemical properties of aerosol were undertaken inside two tunnels located in the MASP in 2011 [67]. The two tunnels showed very distinct fleet profiles: in the Janio Quadros (JQ) tunnel, the vast majority of the circulating fleet are LDV, fuelled on average with the same amount of ethanol as gasoline. In the Rodoanel tunnel (RA), PM emission is dominated by HDV fuelled with diesel + 5% biodiesel blend. The study shows that in the JQ tunnel, PM2.5 concentrations were on average, 52 µg/m3 , with the largest contribution from organic mass (42 %), followed by elemental carbon (17 %) and crustal elements (13 %). While in the RA tunnel, PM2.5 was on average 233 µg/m3 , mostly composed of elemental carbon (52 %) and organic mass (39 %). The work showed that average organic mass:elemental carbon ratio in the JQ tunnel was 1.59, indicating an important contribution of elemental carbon despite the high ethanol fraction in the fuel composition. The study also shows that the sum of the PAHs concentration was 56 ± 5 ng/m3 and 45 ± 9 ng/m3 in the RA and JQ tunnel, respectively. In the JQ tunnel, benzo(a) pyrene (BaP) ranged from 0.9 to 6.7 ng/ m3 (0.02-0. 1 parts per thousand of PM2.5) whereas in the RA tunnel BaP ranged from 0.9 to 4.9 ng/m3 (0.004-0.02 parts per thousand of PM2.5), indicating an important relative contribution of LDV emission to environmental BaP concentration.

The concentrations of PM2.5 and PM10, including their ionic composition was evaluable at an underground bus terminal, being that buses burning fuel blend of 95% diesel + 5% biodiesel (B5) in Salvador, Bahia, Brazil, in 2010 [68]. The results showed that the mean mass concen‐ trations of PM2.5 were 201 µg/m3 during the daytime (8 am-7 pm), while the PM10 were 309 µg/ m3 , during the same period of the day. Three times lower PM10 concentration (110 µg/m3 ) was obtained from an experiment conducted at the same place in 2005, before addition of biodiesel to diesel [69]. The mean concentrations for the total carboxylate anions during the day were 139 and 180 ng/m3 for PM2.5 and PM10, respectively. Results showed that monocarboxylate anions (propionate, acetate, and formate) were the most abundant, followed by ketocarboxy‐ late anions (pyruvate), while the dicarboxylate anions (oxalate and malonate) were the least abundant. The ion Mg2+ (0.43 µg/m3 ) was the most important cation and NO3 - (0.083 µg/m3 ) the main anionic species in PM2.5, while Na+ (0.60 µg/m3 ) and SO4 2- (0.62 µg/m3 ) were the most abundant in [68].

The PM10 concentration (24 h) varied from 38.8 to 92.2 µg/m3 on a bus station, for buses running with diesel/biodiesel fuel blend (B3) in the city of Londrina, Paraná, Brazil, during July 2008 [70]. Nitrate (8 µg/m3 ), sulfate (1.4 µg/m3 ), and ammonium (0.3 µg/m3 ) presented the highest concentration levels, suggesting that biodiesel may also be a significant source for these ions, especially nitrate. The authors also demonstrate that a higher fraction of PAH particles was found in particles with diameters smaller than 0.25 µm in the Londrina bus station, and that the fine and ultrafine particles were dominant among the PM evaluated, suggesting that biodiesel decreases the total PAH emission. However, the authors suggested that use of biodiesel increased the fraction of fine and ultrafine particles when compared to diesel emissions by heavy-duty vehicles obtained in a 2002 campaign [71].
