the Science of the Total Environment into ,he E n ~ n m , n t
and i~s a e l l ( i ~ , h i p ~
The Science of the Total Environment 146/147 (1994) 27-34
Motor vehicle air pollution control in Sweden Larsolov Olsson Swedish Environmental Protection Agency. S-171 85 Solna. Sweden
Abstract One-third of the passenger cars in Sweden today are certified with current state-of-the-art emission control technology. For gasoline-fueled vehicles this involves, for example, closed-loop three-way catalyst control technology. From now on light-duty and heavy-duty trucks and buses also need to be certified against stringent emission requirements. The enforcement program is run to check the equipment's ability to meet the requirements in use and if the manufacturer is meeting their responsibility. The Conformity of Production Audits have shown some of the emission control systems to be preferable and others less so. The In-Use Compliance testing is forcing durable emission control systems. Tests thus performed have revealed potentials to meet lower emission levels than currently required. Urgent need to further cut emissions has guided the Swedish Parliament to adopt a tax incentive scheme with voluntary emission requirements. The manufacturer may chose to certify against a set of more stringent emission standards, and get a lower sales tax on the vehicle. By this scheme the use of USA/California "tier 1' and 'Low-Emission" light vehicles and low-emitting heavy-duty vehicles will be encouraged.
Key words." Exhaust emissions; Motor vehicles; Emission requirements; Tax incentives; Air pollution control
1. Background A l t h o u g h Sweden is not densely p o p u l a t e d and the vehicle fleet is relatively small a n d the vehicles are relatively well m a i n t a i n e d , air p o l l u t i o n is causing p r o b l e m s on several areas: for example, for the health and welfare o f the people, the envir o n m e n t (acidification and ozone), and global warming, etc. T o d a y one finds on Swedish r o a d s - 3.6 million passenger cars. There are - 2 5 0 000 light-duty trucks, - 100 000 h e a v y - d u t y trucks and - 14 000 heavy-duty buses. Only some 100 000 passenger cars and 35 000 light-duty trucks are e q u i p p e d with diesel engines. Virtually all h e a v y - d u t y vehi-
cles are with diesel engines, but only a small percentage o f the light-duty diesel vehicles.
2. Emission from road traffic Air pollutant emissions have been steadily increasing for decades, but are in some cases starting to decrease. This is the case for such pollutants as sulfur dioxide, nitric oxides, c a r b o n m o n o x i d e and h y d r o c a r b o n s . Because o f the large increase in traffic volume c a r b o n dioxide is still growing. R o a d vehicles c o n t r i b u t e a large part o f the emissions of nitric oxides, c a r b o n m o n o x i d e , hyd r o c a r b o n s and c a r b o n dioxide. Emissions from road vehicles started to decrease in 1987 in
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L. Olsson / Sci. Total Environ. 146/147 (1994) 27-34
Sweden, after the introduction of the first models equipped with more efficient emission control technology. Nevertheless, for some categories emissions are still increasing, e.g. the light-duty trucks. Emissions will start to decrease for that category with the introduction of emission control equipment from the 1992 model year. Road vehicles contribute 45% of the total emissions of nitric oxides. Other vehicles, off-road equipment, etc., contribute 19% of the emissions. Approximately 50% of the total HC comes from the vehicles, 30% of carbon dioxide and the major part of the carbon monoxide. Table 1 shows the different contributions by different categories of road vehicles. The air pollutants emitted are known to cause damage to people and the environment. Goals have been set for reduction of these emissions. It is foreseen that the measures hitherto taken will not be enough to reach emission levels that are not harmful. Further measures have to be employed to effect significant reductions in emissions. 3. Emisson regulations in Sweden
Environmentally oriented emission regulations have to focus on the emission performance of the vehicles on the road. More stringent emission legislation requires increasing attention to emission
control design and construction. Following this development, it has become increasingly important to require in-use durability and to run followup checks for emissions from mass production vehicles. It is, moreover, an important fact that effective emission reduction can only be achieved by the manufacture of the vehicle. The follow-up testing has to be effective to fulfill its purpose. It must be available and understood by everyone involved, including the manufacturer. They will know what may happen if vehicles are not conforming to the requirements. The aim is that the manufacturer shall take the whole program into account when the emission control system is designed. Furthermore, the manufacturer's involvement and participation in the enforcement testing and evaluations is very important.
3.1. Enforcement The Swedish emission regulations contain several elements. The emphasis is put on in-use compliance control, resting on the manufacturers responsibility. The programs main elements are certification, conformity of production audits, inuse compliance (recall) testing and periodic inspection. The program is fully effective today for light vehicles. At certification, the manufacturer takes the responsibility to manufacture vehicles in conformity with the requirements and the certified
Table 1 Emission of road traffic air pollution (1000 tons/year, except for carbon dioxide million tons/year) Vehicle categories
Gasoline-fueled passenger cars Gasoline-fueled light-duty trucks Diesel passenger cars Disel light-duty trucks Disel trucks Disel buses Gasoline-fueled trucks and buses Other road vehicles
1,2 0,2 4.1 0.8 0,001
I 0.3 6 2 0.01
1.8 1.0 65 12 0.3
1.2 0.08 4.8 1,3 0.5
2.4 0.6 18 2.1 2.1
The year is 1900 for NOx, for others 1988.
0. I 9,0
Carbon dioxide 10 0.8 0.5 0.1 4.0 0.8 0.06 0.05
L. Olsson/Sci. Total Environ. 146/147 (1994) 27-34
Table 2 Components in Swedish emission regulations for lowemissions: elements for in-use emission performance oriented regulations Manufacturer's responsibility for product compliance Durable emission control systems in working order Standards and other requirements Test procedures Certification of new vechicle/engine models Conformity of production audit In-use compliance testing Manufacturer's emission warranty l/M in use programs (short test)
specification. There are - 2 0 0 passenger car engine families certified for each model year, and 25 light-duty trucks. At the conformity of production auditing (CPA) vehicles are tested against the basic requirements. These vehicles are new, taken from the mass production and only run in. In a first sample, 3 vehicles are tested. If one or more of these emit more than the standard o f one or more pollutants, the test is a fail. Then the manufacturer has to choose between running a second sample test or instituting a remedial action to correct all the vehicles of the model. In-use compliance testing applies the same standards as at certification. The program is run in two phases. The business is expected to be settled after the first round o f surveillance testing, In this pro-
gram a number of vehicles from the same model are tested. These vehicles are less than 5 years of age and have been driven for less than 80 000 km (passenger cars) or 7 years/120 000 km (light-duty trucks) and are representative for the model. Decisions to proceed to a second test phase is taken after review of the test results from the first test. It is only before a vehicle group has been picked for confirmatory test that the manufacturer is able to perform a voluntary action. The effect of the vehicle use other than the ordinary wear and aging are not accounted for in these trials. The most important elements o f the control system follows from Table 2. The emission control equipment is checked for conformity with the requirements at certification, conformity of production audits and in-use compliance testing. Most of the conduct of the system falls upon the vehicle manufacturer. In this report the focus is on the testings and evaluations done in relations to the manufacturer's responsibility for the products conformity with the standards.
4. Exhaust vehicles
4.1. Conformity of production The most recent result from the C P A are presented in the Fig. 1. At the C P A testing very goo results are generally obtained. At these
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Fig. 1. Results of conformity of production tests, 1987-1990 model years. (a) Oxides of nitrogen: (b) hydrocarbons: (c) carbon monoxide; average exhaust emission for light-duty vehicles relative to the standard. For model years 1987and 1988only these vehicles tested were models certified to the current emission standards. The CPA testings were then run against less stringent requirement than applied for the 1989 and 1990 model years.
L. Olsson / Sci. Total Environ. 146/147 (1994) 27-34
Table 3 Exhaust emission at in-use compliance testing of 1989 model year light-duty vehicles Vehicle model
BMW 320i Ford Fiesta CL Mazda 626 2.2i Mitsubishi Galant GLSi Volkswagen/Audi Golf CL
LG20M-87 GCVH-CFI-90 G-22G-89 G6DM-89 G 1.8S066V89
Average odometer reading (Mm)
37 33 25 42 37
90 129 67 45 67
68 101 44 78 40
8 65 8 45 31
4 30 7 26 29
50 55 20
Emissions, average, fraction of the standard (=100)
Between 4 and 6 vehicles from each selected engine family were tested. Average engine family emissions are given in relation to the applicable standard. All selected engine families are equipped with gasoline-fueled engines. (NOAH is an on-highway test.) Source: Durability Compliance of Light Motor Vehicles, Test Reports No. AE60 I-5/91, Swedish Motor Vehicle Inspection Company, 1991 and 1992,
testings vehicles are new and are expected to perform well, similar to the vehicles tested in certification. It is apparent from the results that vehicles of the 1987 and 1988 model years did not perform as well as vehicles of the 1989 and 1990 model years. Experience shows that the results and emission performance of the products stabilize after some years when implementing the same emission requirements. For comparison, typical values for certification are, in g/km, on urban driving cycle, for CO: 1.0, for HC: 0.12, for NOx: 0.22, and, on highway driving cycle, for NOxH: 0.16. In the conformity of production test program 200 vehicles are tested each year, all from the same model year. These vehicles belong to between 15 and 45 different engine families. For example, the 1990 model year test program included 23 engine families.
4.2. In-use compliance testing In-use compliance requirements are applicable to all passenger cars from 1989 and later model years. The test program is set to evaluate the emission performance against the basic emission requirements that the vehicle model/engine family was certified against and the manufacturer's responsibility. Typically 6 vehicles are tested from each engine family. The first round of test is for screening purposes. A second selection and test round may be performed. If the results from the surveillance test reveal a case of non-conformity the manufacturer may elect to perform a voluntary remedial action. The testing program started during 1991. To date some five engine families have been subject to in-use compliance testing. Test results are shown in Table 3. In some cases engine families that have been
Table 4 Exhaust emission at in-use compliance testing vs. conformity of production audits Vehicle model
BMW 320i, etc Ford Fiesta CL Mazda 626 2,2i Volkswagen/Audi
LG20M-87/G20-M90 GCVH-CFI-89/GCVH-CFI-90 G-22G-89 G 1.8S066V89
Model year, A60/CPA 89/90 89/90 89/89 89/90
Emissions, A60/CPA CO
1.8 2.5 1.8 1.7
1.3 1.5 1.2 2.1
0.5 1.3 0.2 1.2
0.9 1.7 0.2 5.8
Comparison of test results from vehicles of the same type (engine family) tested in in-use compliance testing (A60) and conformity of production auditing (CPA). The years are when the testing occurred and when the vehicle completed the mileage. They differ by - 3 years and 30 000 km. (NOxH is an on-highway test.) Source: Table 2 and Conformity of Production Auditing, Test Reports No. AE 8 and 12/89,1 and 6/90, Swedish Motor Vehicle Inspection Company, 1991 and 1992.
L. Olsson/Sci. Total Environ. 146/147 (1994) 27-34
subject to in-use c o m p l i a n c e testing have also been tested earlier for c o n f o r m i t y o f p r o d u c t i o n s testing. One m a y c o m p a r e test d a t a m e a s u r e d at these two instances. The difference is - 3 0 000 k m o f accumulated driving. T a b l e 4 gives the relationships.
4.3. Surveiliance of high mileage vehicles Emission measurements have been m a d e on vehicles o f high mileage, although hitherto only on a limited n u m b e r o f vehicles. Emission d a t a are indicated in Table 5. C o m p a r e d with results from testing at lower mileages, emissions are higher and often exceed standards; 18 out o f 25 vehicles had emissions a b o v e the standards.
5. Emission standards Sweden i n t r o d u c e d the then state-of-the-art emission controls with the s t a n d a r d s a d o p t e d at the beginning o f 1970. These were m a d e more stringent by the 1989 m o d e l year for passenger cars and light light-duty trucks a n d from 1992 for the rest o f the light-duty trucks. These requirements, equivalent to the current U S A s t a n d a r d s and test procedures, are similar to several other E u r o p e a n countries. M a n d a t o r y h e a v y - d u t y diesel vehicle s t a n d a r d s a p p l y from the 1993 model year. The s t a n d a r d s are recorded in A p p e n d i x 1. F r o m the 1993 model year, three different sets o f requirements a p p l y in parallel for each vehicle class. T w o new sets o f s t a n d a r d s are for v o l u n t a r y application. The vehicle/engine m a n u f a c t u r e r has to choose the category to certify against. The
v o l u n t a r y requirements are coupled with a tax incentive scheme.
5.1. The environment categories and tax incentives The v o l u n t a r y s t a n d a r d s and other requirements are based on: (a) s t a n d a r d s for 1994 a n d later model years in U S A ('tier 1') and earlier in California and several o t h e r states, and (b) s t a n d a r d s that apply from the 1992 model year in C a l i f o r n i a (TLEV, p a r t o f the L o w - E m i s s i o n Vehicle program), and subsequently in several a d d i t i o n a l states. The new requirements include m a n y new provisions, as p o i n t e d out in Table 6.
5.2. Future regulations Sweden is aiming for more stringent m a n d a t o r y emission standards. These may be based on the stringency o f the voluntary requirements. In addition, it intends to p r o m o t e the i n t r o d u c t i o n o f clean fuels and the new e v a p o r a t i v e emission control regulation developed by the C a l i f o r n i a Air Resources B o a r d to be effective from the 1995 model year. This p a c k a g e will mean a significant
Table 6 Environmental categories: list of new regulation items added by the Swedish system of tax incentives and voluntary standards, for light-duty vehicles The voluntary requirements mean introduction of a list of new requirements over the mandatory level: • • •
Table 5 High mileage surveillance test results. Vehicles tested for emissions after extensive owner driving No. vehicles
Average odometer reading (km)
Emissions, average fraction of standard (= 100)
Source: Emission from Catalyst-Equipped Vehicles with High Odometer Readings, Erik Kutscher, MTC 9058, Swedish Motor Vehicle Inspection Company, 1991.
Two new sets of exhaust emission standards, with additional requirements. More stringent standards for oxides of nitrogen, hydrocarbons, carbon monoxide and particulates. Application of the California emission regulations for low-emission vehicles (Category l t. New standards for non-methane hydrocarbons. Standards for organic gases and correction for the relative reactivity of such emissions (Category 1). Emissioncontrol system durability t\~r the fully defined useful life. Emissionstandard and test procedure at cold temperature conditions (Category 1). Rulesfor on board diagnostic system (OBD ll) ICategory 1). Required standardized design of the gasoline fuel fill pipe. Interim standards for the in-use compliance testing.
L. Olsson/Sci. Total Environ. 146/147 (1994)27-34
32 step further towards clean vehicle exhaust and evaporative emissions.
useful life, or 80 000 km. Every other option covers the full useful life. New voluntary standards from the 1993 model year carry two sets of standards. Both shall be fulfilled. If nothing is specified the standard is based on the U D C test procedure, also known as the FTP-75 in the USA. Evaporative emission standards refer to measurement o f diurnal and hot soak emissions using a SHED. The second emission standard for oxides o f nitrogen is based on the highway fuel economy test procedure (NOxH). Interim standards for inuse compliance apply for Categories C2 and C1. These are summarized in Table A5. L1, L2 and L3 vehicle groups are defined in Table A4. For further details, see Swedish emission regulations.
6. Conclusions Some concluding remarks may be made based on experiences with the Swedish exhaust emission control program: •
• • • •
Measurement results show higher emissions for vehicles in-use than new prototype vehicles. Emissions tend to increase with aging. Emission regulations are the sole goal for design o f emission control technology. For lower emissions, stringent standards are needed. For design o f durable systems with capabilities to function properly in-use, enforcement and in-use compliance regulations are needed.
7.2. Standards, heavy-duty vehicles For heavy-duty vehicles the standards refer to different use-patterns, expressed in estimated lifetime mileage or engine-running hours that are reached during the first 8 years. There are three such groups. The emission standards are set on the 13-mode test cycle contained in ECE regulation no. 49.
7. Appendix 1: Emission standards Emission standards that apply in Sweden are given in the Tables in this Appendix. The standards are based on differing durability mileages and defined for several different emission test procedures.
7.3. Tax incentives from 1 July 1992 The introduction of the two voluntary sets of emission standards, according to Tables A2 and A3 for light vehicles and C2 and C I in Table A6 for heavy-duty vehicles, is promoted by a reduction of the sales tax on m o t o r vehicles. This is a one-time reduction at the first time the vehicle is taken in to traffic. The amount follows from Table A7.
7.1. Standards, light-duty vehicles For light vehicles the basis for the standards are different for different kind o f vehicles and set/stringency of standards. It is only in the mandatory requirements for light-duty vehicles that the basis for the standards is limited to the half
Table A1 Emission standards summary, mandatory standards for LI and L2 vehicles Vehicle groups
Emission standards (g/km) HC
Useful life (years/Mm)
NOxH is short for test at highway conditions. For LI the standards applied for the 1989 and later model years, and for L2 for the 1992 and later model years. The standards applied on a voluntary basis for LI for the 1987 and 1988 model years, and for L2 for the 1991 and earlier model years. The standards and regulations are those that apply in federal USA for L1 from the 1987 and for L2 from the 1990 model years.
L. Olsson/ Sci. Total Environ. 146/147 (1994)27-34
Table A2 Emission standards summary, Category C2 voluntary standards for LI, L2 and L3 vehicles Vehicle groups
Emission standards (g/km)
Useful life (Mm)
Intermediate useful life
LI I..2 L3
Full useful life
0.16 0.20 0.20
2.1 2.7 2.7
0.25 0.43 0.43
0.05 0.05 --
0.19 0.25 0.29
2.6 3.4 4.0
0.37 0.61 0.61
0.06 0.06 0.06
80/160 80/160 80/200
NOxH is short for test at highway conditions. For the transitional standards for in-use compliance testing, see Table A4. The requirements and standards are the same as those that are to be introduced in federal USA from the 1994 model year (with a phase-in period), called tier 1. Evaporative emission standards as in Table A1.
Table A3 Emission standards summary, Category C1 voluntary standards for LI, L2 and L3 vehicles Vehicle group
Emission standards (g/km) Intermediate useful life
El cold L2 cold L3 cold
Useful life (years/
Full useful life
2.1 6.2 2.7 7.5 2.7 7.5
Other requirements for CI: OBD, filler pipe/openings. NOxH is short for test at highway conditions. Standards for NMOG is nonmethane organic gases. Same useful life as for category C2. Transitional standard for in-use compliance testing, see Table A4. The requirement and standards are the same as have been introduced in California in the Low Emission Vehicle program (the TLEV level of stringency). Evaporative standards as in Table AI.
Table A4 The Swedish light motor vehicle emission regulation groups Group definition
Vehicle groups LI
to/incl. 3500 kg to/incl. 690 kg
to/incl. 2700 kg over 690 kg
over 2700 kg over 690 kg
For Table A1 L2 is L2 and L3.
L. Olsson / Sci. Total Environ. 146/147 (1994) 27-34
Table A5 Interim standards, in-use compliance testing of CI, and C2, LI, L2, and L3 vehicles Emission standard (g/km) L1
Carbon monoxide Hydrocarbons Non-methane hydrocarbons Oxides of nitrogen Particulates Oxides of nitrogen in highway driving
C1 80 Mm a
C2 80 Mm b
C1 80 Mm c
C2 80 Mm d
CI 80 Mm e
C2 80 Mm d
2.1 0.25 0.117 0.25 0.05 0.33
2.1 0.25 0.20 0.25 0.05 0.33
2.7 0.50 0.148 0.43 0.05 1.2
4.1 0.50 0.25 0.43 0.05 1.2
2.7 0.50 0.148 0.43 0.06 1.2
3.4 0.50 0.25 0.55 0.06 1.2
Standards at driving cycle tests in g/km. Other standards apply without transitional arrangements. Interim standards apply to methanol-fueled vehicles. aApplies to the 1995 and earlier model years. bApplies to the 1997 and earlier model years. CApplies to the 1995 and earlier model years. dApplies to 1998 and earlier model year, with some applicable at full useful life. eApplies to the 1999 and earlier model years.
Table A6 Emission standards summary, environmental category C2 and C1, and mandatory C3 Vehicle groups
C3 mandatory C2 CI All < 75 kW 75-150 kW _> 150 kW
Emission standards (g/kWh)
At defined useful life
1.2 1.1 1.1
4.9 4.9 4.9
9.0 7.0 7.0
0.4 0.15 0.15
77 77 77
77 78 80
72 80 72
These standards apply for 1993 and later vehicle model years. The standards are numerically the same as EC directive 91/542. The test procedure is the same as in ECE Regulation no. 49. The regulations are not the same as these, but are the same as those of the US EPA.
Table A7 Tax incentive summary, in SeKr per vehicle of sales tax
Environment category Tax change
Passenger cars, light trucks and buses
gvw < 7000 kg
6 SeKr --- US$1. The C3 category is the mandatory requirements.
gvw > 7000 kg