Background

Beginning in 1996, a number of cities in Sweden established Environmental Zones in the center of each city in order to improve the ambient air quality and also, to a certain degree, reduce noise from heavy-duty trucks and buses. In 1999, similar emission requirements were also introduced by several municipalities for off-road equipment operated in the Environmental Zones. The emission requirements of the Environmental Zones program could be met by retrofitting older diesel vehicles with emission controls, such as catalysts or particulate filters. The Environmental Zones programs by Swedish municipalities were some of the worlds’ earliest diesel retrofit initiatives.

The municipal Environmental Zones programs were not harmonized with European Union regulations. In 2006, the municipal programs were replaced by a national regulation which harmonized the emission requirements in different municipalities, and avoided potential conflicts with EU environmental zones legislation. The national Environmental Zones program is applicable to highway vehicles only, nonroad mobile machinery is not covered by the Swedish Environmental Zones regulation.

Municipal Programs (1996-2005)

Documents:
Environmental Zones regulations, an overview by Swedish Municipalities
Approved aftertreatment devices: onroad | off-road

Onroad Vehicle Program

The first Environmental Zones regulation—which became effective on July 1, 1996 in Stockholm, Gothenburg, and Malmoe—introduced emission control requirements for diesel PM and HC. The regulation was then modified, effective January 1, 2002, by adding a NOx control option. The Environmental Zones program applied to trucks and buses powered by a diesel engine and with a gross vehicle weight of more than 3.5 metric tons. The basic requirement for entering the Environmental Zones was that all heavy-duty diesel vehicles must not be more than 8 years old. Vehicles aged between 9 and 15 years had to be retrofitted with an approved emission control device in order to receive an exemption and to be allowed to travel in Environmental Zones. All vehicles older than 15 years were banned. The required emission reductions for retrofit equipment are listed in Table 1.

Table 1
Retrofit Equipment Emission Reduction Requirements
PollutantEmission Reduction*
Level BLevel C
Particulate Matter (PM)80%-
Hydrocarbons (HC)80%a-
Nitrogen Oxides (NOx)No increase35%
NoiseNo increase
* “Type A” systems of 20% PM reduction were also allowed at the initial stage of the program, until 1999.
a - 60% HC reduction was required before January 1, 2002.

Different aftertreatment devices and their combinations provided different extensions of the traveling period in the Zones, depending on the vehicle model year. As an example, a model year 1993 vehicle was allowed to enter the Zones until 2005 if retrofitted with a Level B system, or until 2007 if retrofitted with a Level B+C system. Special exemptions could be granted for engines meeting Euro IV or better emission standards. Special rules also applied for vehicles designed for special purpose and vehicles seldom traveling in the Zones.

The approved emission control devices were catalytic converters in combination with particulate filters. At the beginning of the program, MTC AB was responsible for approving the retrofit kits and also for the approval of each vehicle. Later, the cities have modified the regulation to allow any testing laboratory with an accreditation to perform the testing and certification services. The emission testing was carried out using a representative combination of vehicle and aftertreatment device on a chassis dynamometer over the Braunschweig City Driving Cycle, representing a typical driving pattern for a bus or a distribution truck traveling in a city area.

When a device was installed on a vehicle, a sticker was placed on the windshield by an authorized I&M station. The enforcement of the regulation was the responsibility of the police.

Estimated 3000 vehicles were retrofitted with emission control systems over the first 3 years of the program duration.

Off-Road Program

Effective January 1, 1999 a similar program was introduced by the cities to reduce emissions from off-road engines. The program was applicable for a variety of applications, ranging from construction machines, wheel tractors, and excavators to lawn movers and hedge cutters. Under the program, contractors had to meet certain environmental requirements to be eligible to bid for municipal contracts. The contractor had to either use only new engines that meet the latest emission standards, or to retrofit older engines with a certified emission control device. Emission control devices used under the program could be either oxidation catalytic converters or oxidation catalytic converters in combination with particulate filters.

The following were the base emission requirements:

  • Highway Heavy Duty Vehicles, e.g. transport trucks used during the construction work, must meet the requirements of the Environmental Zones program.
  • Diesel fueled engines used in all remaining off-road applications must meet at least EU Stage 1 / USA Tier 1 standards for off-road engines.
  • Gasoline fueled engines must meet the US Tier 1 or California requirements.

Diesel engines not fulfilling the base requirements (EU/USA Stage 1/Tier 1) had to be equipped with a certified catalytic converter. For certain applications, expressed as a list of the most polluting machines, particulate filter had to be installed in addition to the catalytic converter.

Diesel engines that fulfill the base requirements had to be equipped with aftertreatment devices at the time they reach 8 years of age. The maximum allowed age of an engine equipped with a catalytic converter was 14 years, and 16 years for engines equipped with a catalytic converter/diesel particulate filter combination.

For gasoline fueled engines not fulfilling the base requirements certain age limitations applied in combination with the requirement that the engine had to be equipped with a catalytic converter. Hand held machines had to be not older than three years. Other engines had to be not older than five years.

Retrofit emission control equipment had to be certified for use under the program. The requirements for approval are listed in the following table. Emissions were tested over the ISO 8178 test cycle.

Table 2
Retrofit Equipment Emission Reduction Requirements (Off-Road)
EngineEquipmentPollutantEmission Reduction
DieselParticle FilterParticulate Matter (PM)80%
Catalytic ConverterHydrocarbons (HC)80%
GasolineCatalytic ConverterCarbon Monoxide (CO)50%
Hydrocarbons (HC)50%

National Environmental Zones Program

In 2006 the individual regulations of Environmental Zones in different municipalities in Sweden were replaced by a national regulation and incorporated in the existing traffic regulation. The new regulation aimed to harmonize the requirements for different municipalities, for the benefit of transportation companies working on a national scale.

The regulation only covers heavy-duty vehicles (trucks and busses) equipped with a diesel engine, with a gross vehicle weight over 3.5 metric ton. These vehicles can be used within Environmental Zones during the first six years after first registration, not counting the year of registration. Older vehicles are not allowed to enter the Environmental Zone, with the following exceptions:

  1. If the engine is type approved (or first registration) according to Euro IV or Euro V, Directive 88/77/EEC, the vehicle can be used during the first eight years after first registration, not counting the year of registration
  2. If the engine is type approved (or first registration) according to Euro IV Directive 2005/55/EC, the vehicle can be used until the end of 2016
  3. If the engine is type approved (or first registration) according to Euro V or better (EEV), Directive 2005/55/EC, the vehicle can be used until the end of 2020
  4. If the vehicle has been adapted to fulfill the emission limits of Euro IV, the vehicle can be used until the end of 2016
  5. If the vehicle has been adapted to fulfill the emission limits of Euro V or better (EEV), the vehicle can be used until the end of 2020

To enter the Environmental Zone, the driver must be able to show a document that verifies which emission standard (Euro class) the engine fulfilled at the time of type approval or registration. However, if the information could be found in the Swedish road traffic registry, no additional document is needed. If the engine has been adopted to fulfill a higher Euro class, the driver must be able to show documents that validate that the engine is in compliance with the indicated Euro class.

This article is based in part on information submitted by Lennart Erlandsson of MTC and by Magnus Lindgren of Swedish Road Administration.