Legal limits on emissions are regulated in some thirty countries throughout the world using various procedures. Given the disparity in the severity of the regulations cycles and the measurement techniques, it is impossible to compare the limits applicable in countries using different cycles as basis.

Car and light truck emissions are measured over the Federal Test Procedure (FTP 75) test and expressed in g/mile. In addition to the FTP 75 test, a Supplemental Federal Test Procedure (SFTP) will be phased-in between 2000 and 2004. The SFTP includes additional test cycles to measure emissions during aggressive highway driving (US06 cycle), and also to measure urban driving emissions while the vehicle's air conditioning system is operating (SC03 cycle).

Tier 2
On December 21, 1999, the U.S. EPA signed the final Tier 2 emission regulations that were proposed in May, 1999. The rule sets new, much more stringent exhaust emission standards for light-duty vehicles to be phased-in beginning in 2004 and establishes new maximum sulfur level in gasoline. Full text of the regulation will be published shortly in the Federal Register.

The Tier 2 standards apply for new passenger cars and light-duty trucks. The program focuses on reducing emissions of ozone-forming gases, including nitrogen oxides (NOx) and non-methane organic gases (NMOG), and particulate matter (PM) from these vehicles. The same set of federal standards, expressed in grams of pollutants emitted per mile (g/mi), applies to all passenger cars, light trucks, and medium-duty passenger vehicles, regardless of the vehicle or engine size. Under this approach, which reflects the EPA's concern with increasing market share and emissions from minivans and sport utility vehicles (SUV), larger vehicles will have to employ cleaner engine and emission control technologies than those needed for vehicles with small engines. The same requirements will apply to all vehicles regardless of the fuel, i.e., gasoline and diesel fueled vehicles will be certified to the same emission standard.

The regulation applies to the following vehicle categories: (1) passenger cars, (2) "light light-duty trucks" (LLDT), at less than 6000 lbs gross vehicle weight rating (GVWR), (3) "heavy light-duty trucks" (HLDT), at more than 6000 lbs GVWR, and (4) "medium-duty passenger vehicles" (MDPV), a new class of vehicles introduced by this rule that includes SUVs and passenger vans rated at between 8,500 and 10,000 GVWR.

The Tier 2 standards will reduce new vehicle NOx levels to an average of 0.07 g/mi. For new passenger cars and light LDTs, these standards will phase in beginning in 2004, with the standards to be fully phased in by 2007. For heavy LDTs and MDPVs, the Tier 2 standards will be phased in beginning in 2008, with full compliance in 2009. During the phase-in period from 2004-2007, all passenger cars and light LDTs not certified to the primary Tier 2 standards will have to meet an interim average standard of 0.30 g/mi NOx, equivalent to the current NLEV standards for LDVs and more stringent than NLEV for LDT2s (e.g., minivans). During the period 2004-2008, heavy LDTs and MDPVs not certified to the final Tier 2 standards will phase in to an interim program with an average standard of 0.20 g/mi NOx, with those not covered by the phase-in meeting a per-vehicle standard (i.e., an emissions "cap") of 0.60 g/mi NOx (for HLDTs) and 0.09 g/mi NOx (for MDPVs). The Tier 2 standards shall be met over a full useful vehicle life of 120,000 miles.

For comparison, the existing Tier 1 standards establish NOx limits of 1.0 g/mi for diesel cars and 0.4 g/mi for gasoline cars over 50,000 miles of vehicle life. Higher limits apply to heavier vehicles, as well as to 100,000 miles vehicle useful life period.

In the anticipation of a possible substantial future growth in the sales of light-duty diesel vehicles in the U.S., the EPA also set stringent Tier 2 particulate matter standards. Manufacturers will have a choice of certifying their vehicles to any of 10 "certification bins", which, for PM, will vary from 0 ("zero emission vehicle"), through 0.01, to a maximum of 0.02 g/mi. Three temporary bins, scheduled to expire at the end of 2006 model year (2008 for HLDTs), allow for certification to up to a 0.08 g/mi standard, which is identical to the Tier 1 PM limit for diesel cars.

The Tier 2 regulation will also reduce average gasoline sulfur levels in the U.S. These reductions could begin to phase in as early as 2000, with full compliance for most refiners occurring by 2006. The program requires that most refiners and importers meet a corporate average gasoline sulfur standard of 120 ppm and a cap of 300 ppm beginning in 2004. By 2006, the average standard will be reduced to 30 ppm with 80 ppm sulfur cap. Temporary, less stringent standards will apply to a few small refiners through 2007. In addition, temporary, less stringent standards will apply to a limited geographic area in the western U.S. for the 2004-2006 period.

Lower sulfur levels will enable improved emission control technology necessary to meet the more stringent standards over the extended useful life of the vehicles. In addition, as soon as the lower sulfur gasoline is available, all gasoline vehicles already on the road will have reduced emissions from less degradation of their catalytic converters.

The adopted regulation has not addressed the issue of sulfur levels in diesel fuel. A concern was voiced during the discussion of the EPA proposal that, unless ultra low sulfur diesel fuels are legislated, the Tier 2 standard is not feasible for diesel vehicles. The EPA said it would address this issue in a separate rule, with a Notice of Proposed Rulemaking (NPRM) expected in early spring of 2000.

According to EPA estimates, complying with the Tier 2 standards will cause a cost increase of less than $100 per passenger car, an average cost increase of less than $200 for light trucks, an average cost increase of about $350 for medium-duty passenger vehicles, and an average increase of less than 2 cents per gallon of gasoline (or about $120 over the life of an average vehicle).

California Low Emission Vehicle (LEV) Standards
Current California LEV emission standards extend until the year 2003. The standards are expressed through the following emission categories:

Tier I
Transitional Low Emission Vehicles (TLEV)
Low Emission Vehicles (LEV)
Ultra Low Emission Vehicles (ULEV)
Super Ultra Low Emission Vehicles (SULEV)
Zero Emission Vehicles (ZEV)

Table  summarizes the California ARB standards for new light duty vehicles.
Car manufacturers are required to produce a percentage of vehicles certified to increasingly more stringent emission categories. The phase-in schedules are fairly complex. They are generally based on vehicle fleet emission averages. After 2003, the Tier I standards will be eliminated as an available emission category.

In California, the same standards apply to diesel- and gasoline-fueled vehicles. The PM standard applies to diesel vehicles only. Emissions are measured over the FTP 75 test and are expressed in g/mile. The additional SFTP procedure will be phased-in in California between 2001 and 2005.

TABLE: 2 CALIFORNIA EMISSION STANDARDS FOR LIGHT-DUTY VEHICLES, FTP 75, G/MI

Emission standards for medium-duty vehicles are summarized in Table 3

Under the LEV II regulation, the light-duty truck and medium-duty vehicle categories of below 8500 lbs gross weight are reclassified and will have to meet passenger car standards, as shown in Table 4. The reclassification will be phased in by the year 2007. Medium duty vehicles above 8500 lbs gross weight (MDV4 and MDV5) would still certify to the medium-duty vehicle standard.

Under the LEV II standard, NOx and PM standards for all emission categories are significantly tightened. The more stringent standards, relative to the LEV, are shown in Table 4 in bold typeface. Beginning with the 2004 model year, all light-duty LEVs and ULEVs would meet a 0.05 g/mi NOx standard to be phased-in over a three year period. A full useful life PM standard of 0.010 g/mi is introduced for light-duty diesel vehicles and trucks less than 8500 lbs gross weight certifying to LEV, ULEV, and SULEV standards, also beginning in 2004.

ii. Euro Norms

Diesel Cars and Light-Duty Trucks
European emission regulations for new light duty vehicles (cars and LD trucks) are specified in the European Directive 70/220. The regulation was last amended in September 1998, when new emission standards for the year 2000/2005 were adopted by the EU Parliament (Directive 98/69/EC). These standards were accompanied by an introduction of more stringent fuel quality rules that require minimum cetane number of 51 (year 2000), and maximum sulfur content of 350 ppm in 2000 and 50 ppm in 2005.

Emission test cycle for these regulations is the ECE 15 + EUDC procedure. Effective year 2000, that test procedure is modified to eliminate the 40 s engine warm-up period before the beginning of emission sampling. All emission limits are expressed in g/km.

The standards for new diesel cars and for light duty trucks are are summarized in the following tables.

The emission norms for petrol passenger cars is as follows:

Table 8: Emission Standards for Diesel and Gas Engines, ETC Test, g/kWh

EU Member States will be allowed to use tax incentives in order to speed up the marketing of vehicles meeting the new standards. Such incentives have to comply with the following conditions:

they apply to all new vehicles offered for sale on the market of a Member State which comply in advance with the mandatory limit values set out by the Directive,
they cease when the new limit values come into effect (i.e. in 2000, 2005 or 2008)
for each type of vehicle they do not exceed the additional cost of the technical solutions introduced to ensure compliance with the limit values.

A new proposal, to be submitted by the European Commission by 31 December 2000, should include:

rules pertaining to the introduction of an on-board diagnostic system (OBD) for heavy-duty vehicles from October 1, 2005 (similarly as provided for in Directive 98/69/EC on the reduction of exhaust emissions from passenger cars and light commercial vehicles),
provisions on the durability of emission control devices with effect from October 1, 2005 (to ensure that they operate correctly during the normal life of a vehicle),
provisions to ensure the conformity of in-service vehicles which are properly maintained and used,

appropriate limits for pollutants currently non-regulated as a consequence of the widespread introduction of new alternative fuels.

iii. Japanese Standards for New Diesel Vehicles Adopted¹²
Japanese emission standards for on-road vehicles and engines are adopted by the Ministry of Transport (MOT). The MOT sets the emission targets an reduction rates based on recommendations by the Central Council for Environmental Pollution Control (CCEPC), an advisory body of the Environment Agency.

Passenger Cars
Emission standards for new diesel powered cars are listed in Table 1. The current test method is the 10-15 mode cycle, which supersedes the older 10-mode cycle (effective 1991.11.1 for domestic cars, 1993.4.1 for imports).

With these short term targets, NO_X emissions will be reduced by 25 to 30 percent and particulate matter by 28 to 35 percent over a period from the year 2002 to 2004. Moreover with a view to maintaining adequate performance of exhaust emissions control in use, the durability requirement will be extended and the installation of OBD systems will become mandatory.²⁷

Expected control technologies include oxidation catalysts, cool EGR, high-pressure fuel injection, intercooling and Turbocharging.²⁷

In additions, automobile manufacturers and petroleum refiners are to carry out technical development so that further reduction of the emissions by an additional 50% beyond the short term targets can be achieved by around 2007. The specific limits and fuel requirements will be determined tend of 2002.²⁷

Trucks and Buses
Emission standards for new diesel fueled trucks, buses, and light commercial vehicles (LCV) in Argentina are summarized in Table 1 (96/94 & 58/94 - Law 779/95). The standards are based on European regulations for heavy-duty vehicles. Truck and bus engines are certified on the ECE R-49 engine dynamometer test cycle.

Emission standards for diesel vehicles
Brazilian emission standards for on-road vehicles and engines are adopted by the Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renovaveis (IBAMA). First vehicle emission regulations were implemented in 1993 (Conama 8/93). The numerical emission limits and certification test cycles are based on European regulations.

Diesel engines can be used in Brazil in heavy-duty vehicles, such as trucks and buses, as well as in light-duty commercial vehicles. Diesel engines are not allowed for passenger cars.

Truck and Bus Standards
Emission standards for new diesel fueled trucks and buses are summarized in Table 1. The same standards apply to both light- and heavy-duty trucks. All truck and bus engines, including those used in light-duty trucks, are certified on an engine dynamometer test cycle (ECE R-49)