NEW international Cabin AIR Index launched

Fleet owners, policy makers and drivers now have access to independent, standardised vehicle ventilation ratings 

• Easy to understand and comparable ratings provide clarity for drivers and car buyers.

• The first independent data set enabling policy makers to protect vehicle occupants.

• The independent Cabin AIR Index rates the ability of each filter and ventilation system to protect vehicle occupants from exterior pollution.

• The A-E colour-coded rating is endorsed by global air quality and vehicle emissions experts.

• Moe information available at www.airindex.com/emissions-ratings/cabin-air-quality-in-cars/   

25 July 2023: Today’s launch of the Cabin AIR Index reveals, for the first time using scientific data, the effectiveness of vehicle ventilation systems and the choice of filters in reducing the exposure of vehicle occupants to harmful pollutants.

Developed from more than five years of independent, international research the new Cabin AIR Index ratings reveal accurately how much pollution enters a vehicle compared to the outside air, when it is used in towns and cities.

Exposure to high levels of pollutants in the air can cause a range of serious health issues including respiratory problems, heart disease, strokes and lung cancer¹.

The air quality inside cars and vans (M1 and N1 categories²) is unregulated, leaving drivers and passengers unaware of the levels of exposure to damaging pollutants. In Europe alone, air pollution is estimated to cause more than 300,000 premature deaths each year³. 

The Cabin AIR Index has been created to inform and empower drivers, passengers, fleet owners and policy makers with the real facts about the protection offered by the ventilation systems and filters in the cars they use and travel in. A simple A-E colour-coded rating, based on a new real-world standard, shows the difference in effectiveness in filtering harmful pollutants.

In 2021 more than 97% of the urban population was exposed to concentrations of fine particulate matter above the health-based guideline level set by the World Health Organization⁴. Drivers and passengers, and in particular professional drivers who are in vehicles for several hours each day are now able to compare vehicles and the filter systems, enabling choice, for the first time based on scientific data.

Today’s launch of the Cabin AIR Index also reveals the significant variation in protection offered by the same vehicle, depending on the type of interior air filter used. When tested on the same car, the combination of ventilation system and one filter was only able to reduce the level of exposure to outside particles for drivers and passengers by 30% during the course of the test, whilst the best performing combination of system and filter achieved 82%.

The Cabin AIR Index ratings show ‘at a glance’ how effective the vehicle ventilation system is, allowing comparison with other vehicles, and other filters installed based on scientifically robust, repeatable, on-road vehicle testing according to the new CWA 17934 methodology.

Massimo Fedeli, Co-founder and Operations Director of the AIR Alliance said: “The health effects of breathing fine particulate matter in urban air are now, sadly, well established and estimated to cause more than 300,000 premature deaths in Europe each year. Drivers and passengers in urban areas may assume that closing windows and using the ventilation system prevents exposure to particulate matter, but that is not necessarily the case.

“Following five years of research, today the AIR Alliance is launching the Cabin AIR Index which rates the ability of the ventilation system to filter the number of particles from outside the vehicle and presents the results in a simple A-E colour coded scale.

“The Cabin AIR Index is the first opportunity for drivers and passengers to see the protection offered by vehicle ventilation systems, and also reveals the difference in performance between different filters fitted to the same vehicle, enabling drivers to make a choice when selecting the filter for their car or van.”

Nick Molden, Co-founder of the AIR Alliance said: “The Cabin AIR Index is based on data collected according to the CWA 17934 methodology, the independent, scientifically robust methodology to collect real drive vehicle interior air quality data. In the absence of any regulations for air quality inside cars and vans, drivers and passengers are unaware of the levels of pollution, and in particular the number of particles which enter the cabin.

“Drivers, and especially professional drivers who are in the vehicle for several hours each day, should be aware that the choice of interior air filter can make a significant difference to the quality of air that they breathe. Our tests show that the same ventilation system fitted with different, but compatible filters, reduced the level of exposure to outside particles for drivers and passengers between 30% and 82%.

“We have worked hard over the last three years with our independent, expert academic and industry group to define standardisation of data collection through the CEN Workshop Agreement 17934. We rate data collected by this method on the Cabin AIR Index providing comparative information between vehicles using fair testing criteria, all conducted on-road in real driving conditions. The same standardised test is applied to each different car type.

“For the first time policy makers and fleet owners have the ability to protect vehicle occupants, using the Cabin AIR Index to define the minimum standards expected to protect occupants.”

The results of the seven filters tested for the AIR Alliance on a 2018 Nissan Qashqai and rated in the Cabin AIR Index are:

*Cabin Air Quality Index (CAQI) as defined in the CWA Workshop Agreement 17934
**the age, make and part number of the interior filter which was pre-installed in the test vehicle was unknown.   

The AIR Alliance has now commissioned a programme of vehicle and filter testing and more results will be added to the Cabin AIR Index periodically.

About the Cabin AIR Index 

Vehicle ventilation systems for cars and vans (M1 and N1 categories2) rated for the Cabin AIR Index are tested according to the CWA 17934 standardised methodology which ensures that the results are independent, repeatable and comparable.

The testing is carried out on a vehicle, sourced independently from vehicle manufacturers, with Pollution In-cabin Emissions Measurement Systems (PIMS) equipment recording the air quality inside and outside the vehicle during on-road driving in towns and cities.

For a result to be considered acceptable for rating in the Cabin AIR Index at least three sperate tests must be conducted on each model, within specific boundary conditions⁵ at an average speed between 30 km/h and 50 km/h, with each test lasting at least 30 minutes.  

Testing is conducted with the ventilation system in ‘fresh air’ mode, the air conditioning turned off, and temperature set to 19°C in either automatic mode, or 50% fan speed if manual, and the vents facing forward and level.

The results of the tests provide the basis to rate the vehicle ventilation systems according to the A-E, colour-coded scale.

Cabin AIR Index ratings

The AIR Index website reports the first tests conducted on a single vehicle with different filters showing Cabin AIR Index ratings A-E. Car buyers and fleet operators should consider carefully the implication for the health of vehicle occupants when selecting the vehicle and choice of filter to minimise the ingress of harmful particles.

Background to the Cabin AIR Index testing process

Emissions Analytics, founded by Nick Molden (Co-founder of the AIR Alliance), was a pioneer in methodologies to test on-road tailpipe emissions using Portable Emissions Measurement Systems (PEMS) equipment. Since 2018 Emissions Analytics has also independently tested the air quality inside vehicles using Pollution In-cabin Emissions Measurement Systems (PIMS) equipment, and the insight gained from more than 100 tests conducted by Emissions Analytics informed the development of the CEN Workshop agreement which led to the CWA 17934 methodology from which the Cabin AIR Index has been created.

For more information see https://www.emissionsanalytics.com/vehicle-interior-air-quality.

¹ World Health Organization https://www.who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health

² Vehicle Approval categories https://www.gov.uk/vehicle-approval/individual-vehicle-approval-manuals

³ Air quality impacts in Europe European Environment Agency https://www.eea.europa.eu/publications/air-quality-in-europe-2021

⁴ Europe’s air quality status 2023 https://www.eea.europa.eu/publications/europes-air-quality-status-2023

⁵ More details about CWA 17934 and the boundary conditions are available at the CEN website https://standards.cencenelec.eu/dyn/www/f?p=CEN:110:0::::FSP_PROJECT,FSP_ORG_ID:76650,2654151&cs=1A37B6A2248CB063033111B9F708BAB58

AIR welcomes the publication of a standardised method to collect vehicle interior air quality data

Emissions Analytics was pleased to support the AIR Alliance with testing to validate this new standardised method for measuring vehicle interior air quality, so it can help reduce the exposures to pollution for drivers and passengers.

Smellovision - Engineering odours in cars

Passenger cars are intricately designed products.  Their impact on the environment is similarly intricate and complex.  We are now moving decisively beyond the age when the dominant impact was exhausting burnt fossil fuel directly to the air.  For modern internal combustion engine (ICE) vehicles, tailpipe emissions have been dramatically reduced even where fossil fuels are still combusted.  Further reductions are potentially within reach with synthetic fuels and increased hybridisation.  

In contrast, other emissions are increasing – not just relatively, but absolutely.  Vehicles are becoming bigger and heavier, leading to greater manufacturing emissions, in-use tyre wear emissions and end-of-life disposal or recycling costs.  Possibly the least understood trend among car buyers is how environmental concerns are impacting the air quality in the vehicle cabin as new and innovative materials, treatments, glues and fragrances are deployed.  While tailpipe pollution entering the cabin has been studied by Emissions Analytics and others, the interaction of the volatile organic compounds (VOCs) from these new interior materials is complex.  However, doing so is important, as these VOC can hang around in the confined space of the vehicle cabin to be inhaled, and can have impacts on aspects from comfort to human health.

The most obvious manifestation of this problem is bad smells in cars.  While Western car buyers tend to like the ‘new car smell’, Asian buyers are less keen.  Removing this new car smell has, therefore, been the focus of regulations in Japan, Korea and other countries.  The reason for this is that due to different physical sensitivities to certain VOCs commonly found in car materials.  But it is not just about the new car smell, as hundreds of VOCs are present in the cabin and they interact in unpredictable ways, which can generate unexpected ‘off odours’.  As traditional materials are swapped for new ‘eco’ or other alternatives, or seat covers are treated with less toxic chemicals, or the vehicle is constructed with more glues rather than rivets, the challenge and risks of bad smells grows.  Further, deliberate science is put by manufacturers into creating desirable, on-brand, odours.

Emissions Analytics is actively developing new methods to design, describe and manage the olfactory contours of vehicles on sale today, and to understand the interaction with the ventilation system to create maximum consumer comfort and minimise any health impacts.  To achieve this, we have taken controlled samples of the air inside a wide range of vehicle cabins and then subjecting the samples to two-dimensional gas chromatography and time-of-flight mass spectrometry analysis to profile the VOCs present in depth.  Our laboratory has been provided by Markes International and SepSolve Analytical.  This method is significant as it allows almost complete separation of the VOCs present, unlike more basic methods that cannot separate the higher molecular weight compounds, which are often the most potentially deleterious.  Even with good separation, identification of the compounds is a challenge as many are not present in the standard spectral libraries.  To resolve this, Emissions Analytics has compiled its own specialist library.

Historically, this sort of odour analysis has been performed by highly trained human ‘noses’.  This has the advantage of directly gaining the human experience, with all that complexity and subjectivity. This remains important as just knowing all the chemicals present does not necessarily mean the human experience can be predicted.  However, where a bad smell is detected, the analytical method provides a way of diagnosing and resolving the problem in a way that a human cannot necessarily do.  

It should also be recognised that off odours do not necessarily correlate with a negative health impact on the human occupants of a vehicle, nor does the absence of any bad smell guarantee there is no impact.  Even where a known toxic chemical is found in a vehicle, it may not be at a concentration that causes an actual negative effect.  Concentration and exposure time are important added dimensions.  The levels of VOC exposures were studied in 2019 of taxi drivers in Barcelona – a group of vehicle users for whom prolonged exposures are an issue.  Given these considerations, Emissions Analytics has been actively contributing to the CEN Workshop 103 that aims to standardise a method for measuring vehicle interior air quality, which will be published soon.  Being able to measure the freshness of air in the cabin will make possible the estimation of VOC exposures.

Looking at the initial testing from a range of interiors, it becomes clear that the VOC soup differs significantly between different manufacturers and of vehicles of different ages.  The table below summarises the findings, including a ‘toxicity potential’ rating.  This is calculated by combining the concentrations measured by Emissions Analytics and information from the European Chemicals Agency database of compounds and their hazard statements.  The rating is a unit-less measure designed for comparative assessment of vehicles.  As can be seen, Vehicle #1 has the highest rating, almost four times the average of the five vehicles, and around 28 times greater than the lowest potential toxicity vehicle, Vehicle #4

With an average of over 800 compounds identified, this demonstrates how rich a mix the air in a car can be, and the complexity of the task to separate, identify and quantify them.  The total concentration of organic compounds is split into four functional groups, from alcohol (generally the least problematic) to polycyclic aromatic hydrocarbons (PAHs) and nitro-aromatics (with the highest incidence of carcinogenic effects).  The alkane and aromatics groups are generally the most prevalent and are often associated with solvents, glues and plastics used in vehicle construction. Vehicle #1 stands out in these respects, whereas Vehicle #3 – low in other respects – is relatively high in PAHs and nitro-aromatics.

Among these compounds, many are common between vehicles.  Across these five cars, the most prevalent ten compounds, with their concentrations and a descriptions, are shown in the table below.  These pumped samples were taken after the vehicle had been soaked overnight in controlled temperature conditions.  The third compound, octanoic acid‚ 2-propenyl ester, is associated with a pineapple aroma in the vehicle.

Beyond these, the individual characteristics of a vehicle tend to be made of some specific, high-concentration compounds and then a long tail of low-concentrations ones.  Taking the toxicity potential score, beyond the top ten common compounds above, the highest rated compound in each vehicle is shown below.

This confirms that Vehicle #1 has a greater potential issue than the other vehicles, but the approach demonstrates that the compounds causing this can be identified and their contribution quantified.  In this way, the manufacturer can diagnose the problem and consider how to alter the construction of the vehicle to mitigate.  This may require substituting materials or methods, but, in doing so, new interactions of chemical compounds need to be assessed as well.

In summary, with ICE vehicles achieving much lower tailpipe emissions and the increased uptake of hybrid and electric vehicles, the impact of non-exhaust emissions is of growing concern for human health and the environment. This means it is now important to obtain a comprehensive view of all possible sources of VOCs from vehicles, including emissions from materials, such as foam, carpeting and seat covers, as well as those generated through tyre wear.

The recent global push towards a circular economy has also meant that automotive manufacturers are being urged to improve the sustainability of their operations by increasing the use of recycled or renewable materials, such as innovative plant-derived plastics. Robust quality control is essential to ensure these novel products will not produce volatile emissions that could be considered harmful or malodourous. Therefore, is not just about vehicle design to create a particular aesthetic, but also for hazard reduction and risk management.

However, the sample complexity, as well as an ever-expanding list of compounds of concern, makes it a challenge for those responsible for performing sampling and analysis. This has led to a need for innovative new methods to be created for complete emissions characterisation. Emissions Analytics is leading through its new laboratory and contribution to standardising measurement methods, with the aim of reducing the overall environmental emissions of future vehicles.

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Are cars sinful?

This is no polemic for or against the car.  Nor about petrolheads.  Nor environmentalists.  This is about the chemicals that are to be found inside cars, and the importance of good ventilation, to avoid occupants gently steeping in a cocktail not of their own making.  The SIN is the ‘Substitute It Now!’¹ list developed by the International Chemical Secretariat, a largely government funded organisation in Sweden² – a list of over one thousand chemicals with harmful health or environmental effects, which they suggest should be removed from consumer products.  But do we find any of these in modern cars?

This is not a new problem, but one the significance of which we are only beginning to understand.  As discussed in previous newsletters, the emissions from vehicle exhausts have improved significantly over the last ten years.  Initially it was mainly seen as particulate reduction, as the widespread cheating on nitrogen oxide (NOx) emissions – of which Dieselgate was emblematic – was only resolved from around 2018 when official laboratory results were validated with an on-road test called Real Driving Emissions.  The remaining pollutants of most concern in the exhaust are carbon dioxide (CO2) and a range of volatile and semi-volatile organic compounds (VOCs and SVOCs).

At the same time, the construction of vehicles has become more sophisticated.  While generally to the benefit of consumers in terms of utility and design, the potential impact on the health and comfort of vehicle occupants has not been fully considered. The increased use of glues in vehicle manufacture and superior construction methods creating an almost perfectly sealed cabin come with downsides.  Significant hurdles in understanding the consequences have been difficulties in measuring the compounds of interest, and the lack of standards to measure vehicle interior air quality (VIAQ).  This is beginning to change, led by South Korea and Japan, which collectively regulate nine different VOCs in the cabin.

Emissions Analytics has been working on this from both angles.  It has been an active participant in a standardisation workshop under the Comité Européen de Normalisation (CEN)³, aiming at measuring the air quality inside light-duty vehicles in terms of particle ingress from outside and CO2 build-up.  In parallel, it has been developing methods for measuring the presence of VOCs and SVOCs in cabin air, and how they might be emitted from the interior materials.  The two areas are linked because the worse the ventilation and filtration system, the greater the likelihood of the accumulation of noxious organic compounds. Multiply that by the length of time typically spent in vehicles and the human exposures could be greater than to ambient air pollution.

To get a measure of the problem, if we chemically analyse the interiors of cars, do we find any of the compounds on the SIN List?  We took a small sample of recent model year vehicles in Europe and analysed a range of interior materials, including dashboard plastic, seat material and carpets.  Each sample was analysed using two-dimensional gas chromatography coupled with time-of-flight mass spectrometry, with sample introduction via microchamber – a system provided by Markes International and SepSolve Analytical.

One vehicle in particular gave interesting results: a top-selling, European-made small car from 2020.  We tested the carpet in the boot and footwell, dashboard plastic and the seat covering material.    Across these sample locations, 16 of the SIN List compounds were identified, as shown in the table below.  The metric is the percentage of the peak area – in other words, the area under the compound’s peak on the chromatogram expressed as a proportion of the total peak area of all organic compounds identified.  It is a reasonable approximation of the relative abundance of the SIN List compounds in each sample.

While just 1.23% of the organic compounds found in the dashboard plastic were on the SIN List, this exceeded 11% for the footwell carpet.  Furthermore, its most prominent compound was diethyl phthalate.  Generally, phthalates are a synthetic substance commonly used to make plastics more flexible.  A growing body of research suggests that many of the compounds in this group have undesirable health effects, including reducing fertility.  As a result, regulations are beginning to restrict their use, for example, under REACH in the EU, the concentration of four target phthalates cannot together exceed 0.1% by weight in consumer goods.  Diethyl phthalate is not one of these four, and the research on its health effects is currently limited, but its high concentration in the footwell carpet should warrant additional focus.

Beyond phthalates, a way to assess the health dangers of the other compounds on the SIN List is to look at the ‘hazard statements’ produced under the Globally Harmonized System of Classification and Labelling of Chemicals (GHS), an international consensus system developed by the United Nations for classifying and labelling hazardous chemicals.  Hazard statements provide standardised wording as to the nature and degree of the threats.  For example, ‘H350’ indicates a chemical that may cause cancer.  An individual compound can have multiple hazard designations.

If each of the compounds identified in the vehicle are scored according to the number of hazard designations, and these are then grouped generically, we obtain the totals shown in the table below.  Included in this assessment are those assessed as ‘persistent bioaccumulative toxic’ compounds, which is a separate hazard category.  These compounds do not break down easily in the environment or living creatures and so progressively build up.

At a high level, it can be seen the most prevalent health effects are irritation or damage to the skin, eyes, throat and lungs.  The boot carpet has the largest number of designations, and contains a relatively high level of octamethylcyclotetrasiloxane, which is suspected of damaging fertility.  The harms are not just to humans, for example naphthalene is also highly toxic to fish and other aquatic life.  

The number and extent of these compounds present in common materials in vehicle interiors points to action needed by manufacturers to address the potential toxicity to occupants.  Beyond the SIN List, we have also identified a ‘PFAS’ in the same vehicle’s seat material.

Per- and polyfluoroalkyl substances (PFASs) are manmade organofluorine compounds, first created in the mid twentieth century and which became popular for their water repellent, stain resistant and non-stick features.  The problem is that they do not break down readily in the environment, hence being described as “forever chemicals”, or persistent organic pollutants.  This bioaccumulation means that it is believed that they are gradually building up inside most living creates as well as the wider environment.

The health effects of PFASs were brought to wide public attention for the first time in the 2019 film Dark Waters, where compounds based on perfluorooctanoic acid (PFOA), a subset of PFASs, were released from an industrial source in West Virginia, USA.  The evidence as to the environmental effects has continued to accumulate.  An article in December 2021 in Environmental Science & Technology shows that these persistent compounds do not simply get washed into the sea and diluted into insignificance.  Rather, waves crashing on the shore recirculate the chemicals into the air and onto land⁴.  This increases the human exposure and associated health effects, which include cancer, thyroid conditions and colitis.

The compound identified was 1H‚1H‚2H‚2H-perfluorooctan-1-ol – chemical formula C8H5F13O – a chain of eight carbon atoms with 13 fluorine atoms attached.  The chromatogram from the seat sample below shows this compound.  Of the total peak area of organic compounds, it accounted for 0.61%.  The hazard classification says that it may cause damage to organs through prolonged or repeated exposure.

It should be added that it is not being claimed that exposure to this seat covering will have direct health effects.  Nevertheless, by the persistent nature of these compounds, they are very likely eventually  to end up in the environment, be recirculated and potentially inhaled or ingested by humans or animals.  PFASs from a car seat add to this gradual and irreversible accumulation.

In the longer-term, the objective should be to engineer these compounds out of vehicles, where there are viable alternative components.  Growing regulations around materials, from REACH in Europe and from the Environmental Protection Agency in the US, together with emerging regulation of vehicle interior air quality led by Korea, Japan, Russia and China, will force the pace.  But how should vehicle owners mitigate the effects in the shorter run?

The concentration of VOCs in cabin air generally increases as the vehicle heats up.  A car parked in the sun will see more chemicals released from the interior materials into the air, recondensing once the vehicle cools back down.  To this chemical soup is added particles and NOx that enter the car through the ventilation system as the vehicle moves, plus the CO2 exhaled by the occupants.

Although not the most glamorous part of a car, a good heating, ventilation and air conditioning system is the best way to limit exposure.  The benefits of maintaining fresh air in confined spaces has been brought to prominence through the Covid pandemic.  The ideal is to keep the ventilation on fresh air mode – rather than recirculation – but this relies upon excellent filtration to minimise the particle and NOx ingress.  In balancing this trade-off, the best vehicles are many times better than the worst, as described in previous newsletters.  Therefore, rating vehicles in a fair and comparable way is urgently needed.

Fortunately, both the car and filtration industries have been actively involved in standardisation of test methods, including through CEN Workshop 103, initiated by the AIR Alliance⁵, which is due to publish its work soon.  Together with the work on vehicle interior air quality through UNECE, it is quite possible to see how these new tools in measurement and evaluation can bring about healthier, and perhaps SIN-free, cars for both the occupants and the wider world.

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References
1. Sinlist.chemsec.org/
2. en.wikipedia.org/wiki/ChemSec
3. CEN Workshop on real drive test method for collecting vehicle in-cabin pollutant data
4. Pubs.acs.org/doi/10.1021/acs.est.1c04277
5. Airindex.com

Side effects may include...

Beware the secondary effects of decarbonisation

No vehicle yet designed generates zero emissions.  Despite much variation geographically, and much argument, battery electric vehicles probably, on average, halve lifecycle carbon dioxide (CO2) emissions when considering first-round effects such as manufacturing and operation. But are the advantages as clear if secondary effects – the side effects – of electrification are considered?

In a previous newsletter, we set out our Eight Principles of Decarbonisation required to meet a real net-zero target, as shown below. By "real net-zero" we mean actually net-zero in a similar way to the "absolute zero" set down in UK FIRES by Allwood et al in 2019.

Vehicle manufacturers are performing increasingly sophisticated lifecycle analyses of their products. However, most do not consider the secondary, or knock-on, consequences of these electrified vehicles. This is our Sixth Principle of Decarbonisation.

These side effects may include the knock-on consequences on energy infrastructure, vehicle design, driver behaviour and traffic patterns. Most immediately, electric vehicles are likely to increase demand on the electricity grid. To meet net-zero, this additional demand will need to be fulfilled with zero-carbon electricity. Cleaning existing electricity will not be sufficient. For any net-zero scenario it is a pre-requisite that the whole future grid is clean, but we will not look at this further here as it is outside the scope of this newsletter despite being foundational to any meaningful solution.

The most frequent concern with battery electric vehicles (BEVs) is that the additional weight compared to equivalent internal combustion engines (ICEs) leads to higher non-exhaust emissions, which may equal or exceed the eliminated exhaust emissions. These non-exhaust emissions from the vehicle come from its brakes and tyres. Road abrasion and resuspension are often included in non-exhaust emissions, but will be set aside here as they do not originate directly from the vehicle.

Emissions Analytics conducted a long-term study on the wear from Continental Contisport 6 tyres on a 2012 Mercedes C-Class driven on the public highway in consistent, normal conditions. For the first 1,200km, with no added payload, the average wear rate was 161mg/km, but over 31,000km the average wear rate fell to 76mg/km. Even this lower value is 15 times higher than the maximum permission exhaust particle mass emissions under current European regulations. Running the same 1,200km test but with 570kg of payload in addition to the driver, the wear rate increased to 194mg/km, an uplift of 21%. In other words, the average uplift was almost 6mg/km for every additional 100kg of payload. For example, on this basis the Jaguar I-Pace would emit 16% more tyre particle wear than the nearest equivalent Jaguar F-Pace, due to the 443kg additional overall weight.

As a reference, the maximum exhaust particle mass emissions permitted in the EU since 2009 is 5mg/km1. Often, real-world emissions on vehicles with a particle filter are well below 1mg/km. Therefore, for every 100kg of extra payload, the added tyre wear emissions may be as much as the maximum allowed out of the tailpipe in total, and more like five times more than the tailpipe emissions in practice.

However, this analysis may overstate the increase. The extensive regenerative braking of the BEV may well reduce brake emissions and the calibration of the electric motors may smooth driving dynamics to reduce tyre wear. On the other hand, ICEs are increasingly incorporating regenerative braking using 48V systems, and the higher torque of the BEVs (27% in the case of the Jaguars) may encourage more aggressive driving. While data is too limited to draw firm conclusions on these mitigating factors, the underlying upwards pressure on tyre wear remains.

Vehicle weight is clearly a crucial factor in vehicle performance and profitability. The Chinese-built Tesla 3 contains a lithium-iron phosphate (LFP) battery, whereas the US-built versions have the nickel-manganese-cobalt (NMC) version. For similar range, the LFP battery is 200kg heavier, but cheaper in construction. That additional 200kg leads to approximately 8% extra energy to propel the vehicle due to increased inertia and rolling resistance of a typical on-road driving cycle. This leads to greater CO2 emissions in the electricity generation, distribution and usage. At the same time, that extra weight may cause 12mg/km of tyre wear, other things being equal. These downsides could be offset by material light-weighting, power and torque limitations and advanced tyre materials – but all come at either added cost or reduced driver utility.

Switching to inside the vehicle, the preoccupation with maximising the range of electrified vehicles – to be competitive with ICEs – may lead to worse vehicle interior air quality. Incoming air to the vehicle’s ventilation system is usually filtered to remove first-and-foremost particles, but this process consumes energy due to the back pressure created by the filter. While this may be insignificant proportionately on an energy-consumptive ICE, it can be material on more efficient vehicles.

Emissions Analytics conducted a test programme across 97 recent model year cars in the US market and found that many hybrids had relatively poor filtration. Tests were conducted on a standardised urban route around Los Angeles. Real-time particle number concentrations, with a lower size cut-off of 15nm, were measured simultaneously inside and outside of the vehicle and the integrated values ratioed over the test. Condensing Particle Counters from National Air Quality Testing Services (NAQTS)2 were used. The testing followed the methodology set down in a Society of Automotive Engineers (SAE) paper authored by Emissions Analytics and the University of California Riverside3.

Not all electrified vehicles performed poorly, but the majority did. The average cabin air quality index from hybrids was 55% worse than the other vehicles in the group, and the particle ingress on the worst was 3.6 times higher than the average of standard vehicles. In contrast, the Jaguar I-Pace BEV was one of the best performers. Although not part of this testing, Tesla’s ‘biohazard’ high efficient particulate air (HEPA) filter, which is now standard on the Models S and X, has excellent reported particle ingress performance, although it will still come at the cost of increased energy consumption.

To quantify this energy consumption, we can look at the mechanics of the ventilation system. A typical vehicle heating, ventilation and air conditioning system consumes from around 140W to 1.4kW depending on the setting4. The lower value is an approximation of the power requirement of the fan and the energy required to overcome the back pressure from the filter. At an average speed of 40km/h, the energy consumption would be between 0.28kWh and 2.8kWh per 100km driven. A typical BEV would consume 25kWh per 100km, so the ventilation system may add between 1.1% and 11% to overall energy consumption. For this reason, there is an incentive to reduce the amount of air filtered, the filtration efficiency or air conditioning activity on electrified vehicles, which would lead to higher particle exposures – and the resulting adverse health effects – of the occupants.

Thinking more widely at the transportation system level, a problem that may start to emerge is added congestion, caused by extra vehicle miles from electric vehicles, which then may adversely affect total emissions from the fleet. This would apply during the transition, while BEV penetration remains relatively low.

A BEV costs approximately 5 pence (5.5 Euro cents) per kilometre in energy costs, compared to 12 pence (13.2 cents) for a reasonably frugal ICE5. Other things being equal, this is likely to lead to more and longer journeys, and a switch to cars from other forms of transport: the income and substitution effects. Setting aside the effects on the economics of public transport, the additional traffic volume will lead to greater congestion, other things being equal. As the fleet will remain predominantly powered by ICEs for decades – due to the legacy light-duty fleet and diesel remaining prevalent for heavy-duty vehicles – this added congestion caused by BEVs is likely to cause increased emissions from these legacy ICEs.

Analysing Emissions Analytics’ database of over 2,000 light-duty vehicles, we can quantify the effect of this added congestion. To travel the same distance at the same speed (65km/h), a driving profile with stopping and starting between 30km/h and 90km/h can create higher emissions than steady-state driving. On average, CO2 emissions are 24% higher, NOx emissions 89% higher and particle number emissions 75% higher. For a period, a relatively small number of BEVs may adversely affect the emissions of the majority ICEs, increasing emissions and worsening air quality. This does not mean the push to BEVs is wrong, but the secondary effect in the short- to medium-term must be considered. One mitigation would be to push faster for BEV penetration.

As congestion leads to longer journey times, the rational response would be for some distance-based or road-access pricing. At least, this would need to compensate for the naturally lower marginal costs of operation of BEVs. More widely, there is a strong argument that motoring generally is under-priced. The pollution produced by an ICE is a negative externality not internalised, which leads to over-consumption.

In summary, these are just three of the potential side effects of electrification. This does not mean that electrification is bad, but that these secondary effects must be understood and controlled. With the large amounts of taxpayers’ money being requested to build the electric infrastructure, there should at least be a responsibility that this is well spent and not just the catalyst for swapping one problem for another.

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Footnotes: 

1. Or 4.5mg/km under the PMP protocol
2. NAQTS
3. Researchgate Publication 333500744 Development of a Standard Testing Method for Vehicle Cabin Air Quality Index
4. Impact of the Air-Conditioning System on the Power Consumption of an Electric Vehicle Powered by Lithium-Ion Battery, Modelling and Simulation in Engineering, 2013
5. Assuming 2.5 miles per kWh and 12.5 pence per kWh for the BEV; 45mpg (6.3l/100km) and £1.20 per litre (€1.33) for the ICE

The Self-Poisoning Car

Real-time emissions of volatile organic compounds in the cabin

Unlike tailpipe emissions, Vehicle Interior Air Quality (VIAQ) is lightly regulated. In the broad area there are existing ISO and SAE standards, and an active United Nations Economic Commission for Europe (UNECE) working group. Some countries have national standards, in particular Japan, Korea, China and Russia. There are 97 VOCs listed as hazardous air pollutants in Title III of the Clean Air Act Amendments of 1990. Overall, the arc of regulation is at an early stage, covers a limited number of pollutants, and has much lower priority and profile compared to the exhaust pipe post-Dieselgate. Nevertheless, the total health exposure of drivers is significant and under-measured.

VIAQ breaks down into three broad areas. The first concerns ingress of pollution into the cabin, especially particles. The second looks at the build-up of pollutants from human occupants, including carbon dioxide from respiration. The CEN standardisation workshop #103 in Europe1, initiated by the AIR Alliance and building on initial test work by Emissions Analytics, is considering these first two elements. The third area, and the subject of this newsletter is the car interior itself and its capacity to emit volatile organic compounds (VOCs) over the life of the vehicle.

What might be colloquially and informally referred to as ‘new car smell’ has typically been ignored, partly because it has been difficult to measure. Recent advances in instrumentation now allow the measurement of not only total, time-weighted average VOCs, but it can now distinguish between different species of VOCs in real time.

Emissions Analytics and Cambridge, UK-based Anatune have worked together to test this ‘new car smell’. The subject has a particular resonance in Asia. 11.2 per cent of buyers in China complained about the odours they found in their new cars, according to the 2019 JD Power China Initial Quality Study.

Car interiors, comprising dozens of separate materials ranging from natural textiles to synthetic polymers and adhesives, emit a wide range of VOCs, among them acetaldehyde. Symptoms that customers have cited range from sore eyes to nausea and headaches, and aggravated respiratory conditions.

Acetaldehyde is especially problematic, owing to the fact that many Asians possess a less functional acetaldehyde dehydrogenase enzyme, responsible for breaking it down. This regional genetic characteristic is one reason why the strictest regulation of VOCs exists in the key Asian markets China, Japan and Korea, and why manufacturers typically observe these regulations for cars that will be sold globally.

However, acetaldehyde is merely one of dozens of VOCs that a car produces. The sources are typically:

• Residual compounds from the manufacturing process and material treatment of different interior components and textiles

• Adhesives and carrier solvents that will de-gas – as much as 2kg of adhesive can be found in a modern car, much higher than in the past where mechanical riveting and bolting was more common

• Degradation of cabin materials over the longer term as a result of oxidation, ultra-violet light and heat.

The following table sets out the regulated limits in key Asian countries, in micrograms per metre cubed, and the potential human symptoms from exposure.

In this testing, not only did we manage to isolate different VOCs, but we quantified their mass using SIFT-MS, a type of direct mass spectrometry that uses precisely controlled soft ionisation to enable real-time, quantitative analysis of VOCs in air, typically at detection limits of parts-per-trillion level by volume (pptv).

Anatune provides chromatography and mass spectrometry-related analytical solutions, in particular the deployment of SIFT-MS, which stands for Selected Ion Flow Tube Mass Spectrometry and is built by the Christ Church, New Zealand-based company Syft Technologies. One of the main advantages over existing instrumentation is that SIFT-MS measures multiple analytes in real time, akin to a rolling video compared to the ‘snap shot’ of traditional chromatography.

As with any technology, there is a trade-off with the more traditional technique of thermal desorption/gas chromatography (TD/GC) analysis, where VOCs are collected on sorbent tubes on an integrated basis. The SIFT-MS approach cannot distinguish every analyte, and the most effective way to operate the instrument requires ‘telling it’ what you are looking for in advance.

In an initial test of a one-year-old gasoline Hyundai i10, Anatune deployed the Syft Technologies’ Voice 200ultra.

The car was tested every 15 minutes for 60 seconds over five hours on an early summer’s day, where temperatures rose to 20 degrees Celsius (68 degrees Fahrenheit). The measured concentrations were expressed as the mean across the 60-second duration of the sample. For the final 15-minute vent cycle, the car windows were opened, the car started and the air conditioning run at full power. The SIFT-MS then sampled continuously using the above conditions for the full 15 minutes.

The two principle outcomes of the test concern the steady accumulations of ten VOCs as temperatures rose; and the unexpected dynamic of emissions during the final fifteen minutes.

Most noticeably, the common solvents methanol and acetone rose from very low base points (18 and 12 micrograms per cubic metre) to 935 and 576 μg/m³ respectively. The 52-fold rise in methanol is noteworthy. While it is a very common solvent and not directly regulated, it is toxic and could be an irritant at these levels.

The only exception to these across-the-board rises was benzene, which fell from 17 to 15 μg/m³. However, this is where the final fifteen minutes revealed unexpected results.

Despite windows being open and the air conditioning turned on, some VOCs such as acetaldehyde rose steeply during the fourth to sixth minutes. During this phase acetaldehyde concentrations rose from an initial base of approximately 50 to 550 μg/m³, more than ten times the regulated limit in China and Japan.

Anatune Senior Application Chemist and SIFT-MS Specialist Dr Mark Perkins hypothesises that the car’s Heating and Ventilation system (HVAC) may form a type of ‘sink’ for some VOCs. When the venting or AC are activated, the sink is flushed out into the cabin causing a pronounced spike. Three other analytes that rose in the same time frame included styrene, toluene and benzene.

From a vehicle testing perspective, the ability to detect and speciate different analytes in real time opens up the possibility for more extensive research of exposure and the potential for regulation to reduce detrimental health exposures. It could also assist driver education in respect of ‘VOC build-up’ when a vehicle is parked in hot weather.

Overall what this shows is that a four-hour, time-weighted average of total VOCs – the basis of existing regulatory testing – could be improved. Future regulations will need to cover individual materials in isolation as well as ‘whole car testing’, by which we mean the actual, real-world way in which the many materials comprising a car interior act dynamically with each other and within the HVAC system.

With so many new entrants into the global car manufacturing sector, and at a time of drivetrain and material changes often connected with light-weighting, there has never been a more critical juncture at which to take seriously chemical emissions that can harm vehicle occupants and are already the source of a high volume of complaints.

Regulations should reflect where there is market failure, in particular where a consumer does not realise or cannot do anything about the health exposure. ‘New car smell’ may be unpleasant to certain consumers, but there is little understanding of the health detriment. Acetaldehyde is one of the better understood VOCs in the cabin so far, which was prominent on the vehicle tested, and which should be considered for early intervention.

¹ CEN Workshop 103 held its first meeting on 4 November 2019, chaired by not-for-profit organisation the AIR Alliance, whose co-founder is Emissions Analytics' founder and CEO Nick Molden.