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Vehicle Exhaust Emissions

Vehicle Exhaust Emissions: What They Consist Of

In February last year, the European Parliament voted to approve a law banning the sale of petrol and diesel vehicles from 2035 onwards. This is part of a bigger mission to achieve a 100% reduction in vehicle CO2 emissions before 2050.

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Of course, the European emissions regulations have been in place since 1970, with the first EU-wide legislation being implemented in 1992 – when catalytic converters became compulsory on new designs.

Since then, there has been an evolution of standards, ranging from Euro 1 to Euro 6, all of which have aimed to cut dangerous emissions from our vehicles to ensure the damaging impact of vehicle air pollutants is ultimately eradicated.

What Do Vehicle Exhaust Emissions Consist Of?

We mentioned before that catalytic converters became compulsory in the 20th century. Without a catalytic converter, cars can emit carbon monoxide gases of around 20,000 to 40,000 ppm – falling to just 200 ppm at the tailpipe when working.

This is also assisted by the lambda sensor, of which you can find two on modern cars. These improve the efficiency of combustion by measuring the oxygen in the exhaust and ensuring the catalytic converter is working correctly, working to optimise air and fuel mixture and reduce the impact of harmful gas emissions.

When we say ‘harmful gas emissions’, however, this doesn’t just refer to carbon monoxide. Exhaust emissions include a mix of gases and particles, with the combination of these fumes playing a major part in the current climate change crisis – according to a 2022 statistic, transport is the largest emitting sector of greenhouse gases. These substances include:

  • Carbon Dioxide

Although CO2 is technically non-toxic, a large volume of this gas contributes to ocean acidification, which ultimately warms the atmosphere and causes climate change. Due to vehicles and other human inventions, CO2 has risen in the atmosphere by 50% in the last two centuries.

  • Nitrogen Oxides

Nitrogen oxides are also produced by vehicle emissions, and they’re highly reactive, contributing to climate change when mixed with other airborne pollutants.

  • Sulfur Dioxide Vehicle Exhaust Emissions

Another result of vehicles is the influx of sulfur dioxide, which is known to form acids and lead to both smog and engine corrosion. This occurs naturally in crude oil, which is used to refine petrol and diesel.

  • Benzene

While benzene appears in minute quantities, it is still a carcinogenic substance that can negatively impact human health when inhaled.

  • Hydrocarbons

Hydrocarbons can also be found in car emissions, especially if there is any unburnt fuel due to ineffective combustion. The main byproduct of hydrocarbons is an increase in CO2, as well as other greenhouse gases.

  • Particulate Matter

Along with these emissions, diesel engines also emit soot and metal, which is known as ‘particulate matter’. Recent studies have shown that long-term exposure to these airborne particulates can cause increased mortality, with links to heart disease, chronic bronchitis, reduced lung function, and cancer.

car emissions

What Standards Do You Need to Know About?

As a responsible car owner, it is your job to familiarise yourself with the meaning of vehicle emission standards – has published a good overview of the exhaust emission characteristics of light vehicles, complete with information on Euro 1 to 6 – to ensure you are doing your bit for the environment.

As mentioned earlier, installments like the catalytic converter, lambda sensor, the EGR valve, and standards including a reduction of NOx limits have ensured cars are continually growing safer. But your job doesn’t stop there. Each of these components must be continually tested, however, and it’s important to recognise the signs of failure.

It’s also essential that you work to reduce your driving emissions. This can be achieved in several ways, with some of the most popular being the use of better fuel—premium, super, or ultimate diesel—containing active cleaning agents to improve efficiency—changing the oil, changing the air filter, checking tyre pressure, reducing the amount of air conditioning we use, and, of course, choosing manufacturers who innovate in the environmental space.

The world is heading toward a cleaner and better future, so make sure you are doing what you can to remain vigilant and put the climate first.

Information sources: meaning of vehicle emission standards – more on the effect of the lambda sensor on exhaust gases on


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