Emissions Standards

The Zero E Standards for Exhaust Emissions

The Zero Emissions engine efficiency test assesses four exhaust emissions and the Lambda air-to-fuel ratio in a petrol engine, and the opacity of the exhaust in a diesel engine. A vehicle achieves a level of efficiency on the basis of our Zero e2, Zero e3 and Zero e4 standards which are based on the Euro II, Euro III and Euro IV standards for exhaust emissions. Vehicles passing at least the Zero e2 Zero standard for exhaust emissions are given a badge of honour.

Carbon Monoxide (CO)
Carbon monoxide is a colourless, odourless, poisonous gas and results from the incomplete combustion of fuel. It is most likely to occur when the air-to fuel ratio in the engine is too low, when the engine is started and the air supply is restricted, when cars are not tuned properly, and at higher altitudes where thin air effectively reduces the amount of oxygen available for combustion. The normal level for CO emissions on a vehicle fitted with a catalytic converter is less than 0.5%.

The Zero e2 standard for CO is less than 2.5% at both low and high idle.
The Zero e3 standard for CO at idle is less than 0.5%, at high idle less than 0.3%.
The Zero e4 standard for CO at idle is less than 0.3%, at high idle less than 0.2%

Hydrocarbons (HC)
Hydrocarbon emissions are fuel molecules that are only partially burned. They react with nitrogen oxides and sunlight to form ground-level ozone, a major component of smog. Ozone irritates the eyes, damages the lungs, and aggravates respiratory problems. It is our most widespread urban air pollution problem. A number of exhaust hydrocarbons are also toxic and have the potential to cause cancer. The normal level for HC emissions on vehicles fitted with a catalytic converter is less than 80ppm.

The Zero e2 standard for HC is less than 300ppm at both low and high idle.
The Zero e3 standard for HC is less than 100 ppm at both low and high idle.
The Zero e4 standard for HC is less than 50 ppm at both low and high idle.

Carbon dioxide (CO2)
Carbon dioxide is a by-product of burning fuel. The higher the percentage of CO2 in the exhaust gases, the more efficiently the engine is running. A high CO2 reading is good because it means the engine is running efficiently and the car therefore produces less CO2 during a journey. Carbon dioxide does not directly impair human health but it is a greenhouse gas that traps the earth's heat and contributes to global warming.

The normal level for CO2 emissions on a vehicle fitted with a catalytic converter is 14.5% or higher.

Oxygen (O2)
During combustion, the more oxygen that is burnt the better. Normally, the oxygen level in the exhaust will be low. Assuming the exhaust system is in good condition and has no leaks, a higher level of O2 indicates there is a misfire in the engine.

The normal level for O2 emissions in a vehicle fitted with a catalytic converter is less than 0.5%.

Lambda
Lambda is a measurment of the ratio of air-to-fuel present during combustion. When all the fuel is combined with all the free oxygen in the engine’s combustion chamber, the mixture is chemically balanced and the engine will run efficiently. Lambda is an important measure because it indicates whether the car is polluting the air and needs tuning. Typical readings on a well-tuned engine are between 0.95 (rich mixture) and 1.05 (lean mixture).

The Zero e2 standard for Lambda at both high and low idle is 0.90-1.10.
The Zero e3 standard for Lambda at both high and low idle is between 0.97-1.03.
The Zero e4 standard for Lambda at both high and low idle is 0.97-1.03.

Diesel Opacity Test and “k” value
The Diesel Opacity Test is an excellent tool to ensure a diesel engine is properly maintained. This test is used to improve fuel economy, reduce air pollution and protect our health.

The Diesel Opacity Test indicates how much pollution is coming from the engine and whether the engine is running efficiently, by measuring the emission of black smoke coming from the vehicle’s exhaust. This smoke is partially burned fuel which has not been converted into energy.

Black smoke is made up of small particles called particulate matter. Particulate matter, especially the tiny particles smaller than 10 microns, are a health hazard and have been linked to cancers and respiratory diseases such as asthma.

An opacity meter is used to measure the amount of light blocked in smoke emitted by diesel engines. The opacity of smoke is indicated in units called the k value.

Passing the Diesel Opacity test will assure the vehicle owner that their diesel engined vehicle is not wasting fuel and not emitting particulate matter that pollutes the air and threatens our health.

The Zero e2 standard for the k value is 3.5.
The Zero e3 standard for the k value is 3.0.
The Zero e4 standard for the k value is 2.0