Indeed, many car-owners may be surprised to learn that a Vauxhall Astra (c.8000GBP) actually delivers cleaner air than a top end Jaguar E Pace with a price-tag three times higher.

This month, Emissions Analytics, an independent global testing and data specialist for the scientific measurement of real-world emissions, tested 11 cars to assess their ability to purify the air coming into the car from air vents. It is an unavoidable fact that the exhaust fumes from other vehicles enter the cabin of your car though the ventilation system and are supposed to be filtered by the air filtration systems within your vehicle, however, the data from Emissions Analytics suggests that some cars, for example the Toyota C-HR, are filtering out just 1% of external pollutants.

To what extent this polluted air causes physical injury is unknown, however, there is a long established relationship between air-pollutants and certain types of cancer, heart disease and stroke, whilst people with asthma and young children may be at greater risk. The new report found that there are 57,000 toxic particles in every cubic centimetre of roadside air. Suggesting drivers could be inhaling up to 28 million particles with every breath.

Crucially for consumers, this exposure to pollutants is preventable. The Mercedes E Class, for example, filters up to 90% of pollutants from air flowing into the vehicle.

However, for most car-buyers an assessment of the efficacy of the air-conditioning filtration system will not form any substantive part of their choice of car. Many will presume that air filtration will be standardised and subject to industry regulation.

It is not.

On publication of the report from Emissions Analytics, the Society of Motor Manufacturers and Traders confirmed that the lack of regulation meant that manufacturers could use any specification of air filter they want. They confirmed the industry is “working with policy makers” to decide if new rules are required.

Exactly what policy recommendations will emerge from these discussions has yet to be seen, however, in light of the hazardous nature of the pollutants produced – anyone who owns or travels regularly in a car will have an interest in ensuring that this potentially dangerous exposure is better regulated across the industry. The fact is that if you are driving a vehicle for work, you are likely to spend several hours each week in your car, in traffic, on motorways, breathing in hazardous pollutants that your car manufacturer has the know-how to prevent but which it is not currently compelled to do.

As a consumer, car-owners currently have neither the protection, nor the information to make an informed choice about the quality of the air-filtration system within their vehicles.

As often is the case, the data now published by Emissions Analytics has a US precedent, with researchers in California, back in 1997 reporting that exposure to toxic compounds inside your vehicle was as much as 10 times higher than in the surrounding external air, as a result of intense pollutant exposure.

So why has nothing been done? With the new Ultra Low Emission Zone coming to London in April 2019, most road vehicles including cars will need to be adapted to meet new, tighter exhaust emission standards. As such, there is an opportunity here, for the car-industry to clean up its act and move towards the regulation of ‘in-vehicle’ air-filtration systems. Only when vehicle emissions are subject to industry wide permissions will car-owners be able to breathe more easily and more safely.