Which Is Worse for Pollution, Diesel or Petrol? 


The debate surrounding diesel and petrol cars has been going on for years. Which of the two is safer for the environment and human health? Which of the two should vehicle manufacturers and car owners favour? If the fight against air pollution is to be taken seriously, it is essential to determine the answers to these questions. 

Petrol emissions 

A highly flammable and toxic liquid, petrol (gasoline in the US) contributes to air pollution through the vapours it releases when it evaporates. This includes particulate matter, carbon monoxide, unburned hydrocarbons, and nitrogen oxides or NOx. When petrol is burned, it releases CO2 or carbon dioxide.  

Petrol originates from crude oil, a fossil fuel that comes from dead organisms’ remains and is found underground in reservoirs. It is used for the engines of aeroplanes, motorbikes, large ships, buses, lawnmowers, and road transport (cars and vans).  

What makes petrol dangerous are the by-products that it produces through a vehicle’s combustion process. Petrol emissions contain: 

  • SO2 or sulphur dioxide, which causes acid rain and leads to heart conditions or breathing difficulties 
  • CO2 or carbon dioxide, which is a greenhouse gas that is a significant contributor to global warming 
  • PM or particulate matter, which forms fog, haze, and ground-level ozone and causes health issues such as asthma and other respiratory issues 
  • The poisonous gas CO or carbon monoxide 
  • Lead, which produces toxins that can cause health issues and form ground-level ozone 
  • VOC or volatile organic compounds, which have adverse effects on the lungs 
  • NOx or nitrogen oxides, which have dangerous impacts on the environment and a person’s health 

Diesel emissions 

Named in honour of its founder Rudolf Diesel, diesel fuel is used in road transport such as cars, buses, trains, and heavy-duty trucks. Like petrol fuel, it comes from crude oil.  

There was a time when diesel fuel in the United States contained sulphur in large quantities, which is known to produce harmful emissions. This was corrected by the Environmental Protection Agency in 2006 when they required the sulphur content in diesel to be significantly reduced before the fuel could be sold in US markets.  

Diesel fuel emissions have the same dangerous by-products are petrol fuels: 

  • Carbon dioxide 
  • Sulphur oxides 
  • Carbon monoxide 
  • Nitrogen oxides  

NOx emissions from diesel vehicles have life-threatening environmental impacts, including damage to vegetation. They also cause health impacts such as asthma, cardiovascular diseases, and premature death.  

Diesel used to be the preferred and recommended fuel by the majority of vehicle owners, governments, and environmentalists. This changed in 2015 after the Dieselgate diesel emissions scandal broke out. 

In September of that year, US authorities sent a notice to the Volkswagen Group after they discovered defeat devices in Audi and VW diesel vehicles sold to American consumers. These devices can sense when a vehicle is in regulatory testing so that they could temporarily suppress vehicle emissions to levels that are within WHO-mandated limits.  

While a defeat device-equipped vehicle appears fuel-efficient during tests, it emits massive volumes of NOx emissions when driven on real roads. Thus, it is a high-polluting vehicle.  

Mercedes-Benz, BMW, and Renault are some of the other carmakers implicated in the diesel emissions scandal. 

So, which is more dangerous? 

Diesel fuel and petrol fuel each have positive and negative factors. They have similar by-products and impacts on the environment and human health. There are several differences, though, and these summarise everything: 

  1. Diesel-powered vehicles have lower greenhouse gases (GHG) and CO2 emissions. 

The compression ratio of diesel engines is better and higher compared to petrol-fuelled ones. As such, diesel vehicles use lesser fuel even if their travel distance is the same as petrol vehicles. This means fewer greenhouse gases are emitted.  

However, this is not proof that diesel is the lesser pollutant of the two.  

  1. Petrol vehicles have fewer fine particles.  

Petrol vehicles were more efficient compared to old diesel vehicles specifically when it came to fine particles. Diesel-fuelled engines released more of these particles than petrol engines did. The newer models are better, though, because they are already equipped with particulate filters. However, while these reduce the volume of fine particles emitted, the technology isn’t perfect. 

Still, petrol fuels emit lower amounts of fine particles. This is not proof, though, that petrol engines are better than diesel ones. There are several factors to consider, including vehicle size and weight, purpose or use (ex. for long-distance travel), vehicle type, frequency of vehicle use, and injection system utilised. 

Since petrol fuel is typically used in smaller vehicles and releases lesser amounts of fine particles and CO2, it is often considered less dangerous than diesel. There is no guarantee of this, though, as emissions can now be easily manipulated. 

The best option for car manufacturers and owners is not petrol or diesel; it is the EV or electric vehicle.  

Diesel emissions claim 

Diesel vehicles fitted with defeat devices contribute large volumes of air pollutants, which is why affected car owners are encouraged to bring a diesel claim against their manufacturer. Carmakers should be held responsible for lying to their customers by selling vehicles that are equipped with defeat devices that cheat emissions tests. 

Before you can start the claims process, however, you have to visit ClaimExperts.co.uk to verify your eligibility to make an emissions claim. Once your eligibility is confirmed, their panel of solicitors will assist you. Visit their site here

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