Skip to content

Exhausting Traffic: A Study on Local Traffic Emissions

Share on facebook
Facebook
Share on twitter
Twitter
Share on linkedin
LinkedIn

We all agree that traffic can be exhausting. But it can also simply be exhaust. Vehicle exhaust emissions originate from their tailpipes and have been strongly regulated to tackle emissions of air pollutants. However, Maltese researchers recently found that this type of emission is not the major contributor to particulate emissions from vehicles. THINK takes a closer look under the hood.

Transport-related air pollution has an adverse effect on public health. Current policies have been addressing this problem, aiming to improve air quality by decreasing concentrations of transport-related pollution.

To date, only contaminants which originate from vehicles’ tailpipes – also known as vehicle exhaust emissions – have been regulated. The increased use of electric cars will lead to decreased emissions of pollutants such as carbon monoxide, benzene, and nitrogen oxides. While we can breathe a collective sigh of relief, exhaust emissions are not the only culprits that need to be tackled, nor are they the worst.

‘Shifting to electric cars will only solve the exhaust part of particulate matter from road traffic. We still face a major problem regarding other sources of particulate matter,’ highlights Dr Mark Scerri, lecturer at University of Malta’s Institute of Earth Systems. In a recent study, local researchers demonstrated that for Msida (a town in the Central Region of Malta), traffic-generated particles are the main pollution source to be considered (38.4% of total emissions). However, only 3.4% of traffic-related particles were due to exhaust emissions. The remaining 35% were due to road dust, tyres, and brakes. These are collectively known as non-exhaust emissions. These non-exhaust emissions constitute 87% of yearly traffic-generated particles and are considered detrimental to public health in particular. But what do we really know about non-exhaust emissions?  

Non-Exhaust Emissions

To understand which sources could be contributing to emissions, the researchers collected data at an Msida traffic site with a sampler over the course of a year. The particles were subsequently analysed chemically in a lab, allowing researchers to identify the source of these particles. Interestingly enough, a portion of these particles came from natural sources, such as sea salt and Saharan dust. ‘A logical contributor since we live on an island near to North Africa,’ laughs Scerri. However, the most surprising result was that the bulk of traffic-generated pollution was not released from exhaust pipes, but from non-exhaust emissions.

Non exhaust emissions are caused by friction between the tyre and the road surface, the resuspension of dust particles previously deposited on the road, and the abrasion between the brake pad and the wheel.

These emissions consist of particles suspended in the air, also known as suspended particulate matter (PM). Particles with a diameter of approximately 10 micrometres (microns) or smaller are referred to as PM10, while particles with a diameter of approximately 2.5 microns or smaller are PM2.5. To put this into perspective, a human hair is around 70 microns wide. Both types of particles are small enough to penetrate deep into the respiratory system, aggravating symptoms of asthma or even leading to lung cancer. Contrary to PM10, PM2.5 levels in Malta have decreased over time. ‘It seems a small detail, but we have to remember that the longer we are exposed to these emissions, the worse the outcome will be,’ reinforces Scerri. 

Impact on Policy-Making

While electric cars do reduce exhaust emissions, they still cause non-exhaust emissions through tyre erosion, road particle resuspensions, and brake-pad abrasion. Since these are not effectively regulated, the change to electric cars will not have a major effect on PM10 levels in the environment. In fact, by carrying a rechargeable battery to provide energy, the electric vehicles’ additional weight could provoke equal or higher PM10 emissions than conventional cars.

‘We are not saying that we shouldn’t change to electrical vehicles. We do believe that the use of electric vehicles should be considered, but as part of a basket of measures to control the emission of harmful particles and gases into the atmosphere. However, both electric and non-electric vehicles are impacting our health,’ the researcher explains. ‘We must invest more in mass mobility – public transportation – and policy making.’

At the European level, discussions addressing non exhaust emissions and their proper regulation are ongoing. Considering the extreme difficulty in achieving this goal, it is crucial to understand transport demand and traffic activities; ambient air quality, exposure, and effects; as well as urban planning. This requires information from several research areas, often creating transdisciplinary studies and teams.

Decision-makers and risk managers often ask what is the significance of the various components of the pollution emitted by transport that produce adverse health effects? Identifying such components would help risk managers focus their efforts and enable a more forceful reduction of adverse effects on health. The elimination of lead from petrol is an example of this approach; it has resulted in a substantial reduction in exposure to lead and its harmful effects on the neuronal development of children.

As mentioned by the researchers to THINK magazine, risk-reduction measures should be extremely calculated, as they may inadvertently have both positive and negative effects. For example, reducing exhaust emissions by increasing the proportion of electric cars may lead to increased PM emissions.

By discovering that the bulk of traffic-generated pollution is due to non-exhaust emissions, local researchers have helped identify one of the main pollution sources related to traffic in Malta. Understanding which pollutants people are involuntarily exposed to is crucial in order to improve the effectiveness of further action. ‘That’s why science should play an important role in policy-making decisions on – amongst other issues – transport-related matters and in evaluating its benefits and costs to society,’ states Scerri.

Author

More to Explore

Fostering Creativity and Community: The ART Connect Project at the University of Malta Library

The Library is, in many ways, the beating heart of the University of Malta (UM). The pulse of intellectual life can be felt most profoundly amongst the quiet shelves lined with books and the many students and academics lining the Library’s work desks with their noses deep in their projects. In this sense, the Library is also symbolic of the University’s overall health and vitality, so it is important to balance serious work with serious play.

The evolution of the ART Connect Project has been a journey of dedication and transformation. Inspired by the vision of new librarians and a desire to revamp the Library’s decor, what was once a seed of an idea has now matured into a vibrant platform for artistic expression, collaboration, and community building.

The ART Connect Project aims to connect people through creativity, foster collaboration, and transform spaces, inviting artists and art enthusiasts to celebrate the power of art.

Meeting Challenges Halfway at the Malta Book Festival 2023

Malta boasts 58 registered publishing entities, hosting hundreds of authors writing books across a wide swathe of genres and formats. These numbers emerge from an NSO survey into the book industry, conducted on the basis of the year 2021. Effectively, we could say that there are ‘more authors than churches’ in Malta, with over 700 authors populating the National Book Council’s database.

This hints at a varied industry, the stakeholders of which all fall under the remit of the National Book Council, which seeks to assist, support, and represent Maltese authors and publishers, as well as related industry stakeholders such as translators and illustrators. While the Maltese context does have its own particularities, neither is it immune to the industry’s wider, global realities, a case in point being the price hike on paper caused by the war in Ukraine, which continues to be felt across the board. Maltese publishers must also bear the brunt of this unfortunate phenomenon.

The National Book Council continues to advocate for increased governmental support to aid publishers, whether in this particular challenge or others, and it also offers direct financial aid through the Malta Book Fund, which last year issued a grand total of €120,000 to various industry stakeholders, targeting projects of high cultural value which may not have a straightforward route to market success.

But while some challenges may be met halfway through financial incentives, others require a systemic — or cultural — shift in attitude from all parties involved, which takes a certain degree of workshopping to be borne out. The slow uptake of ebooks bears pondering (the NSO survey saw 146 new ebooks issued in Malta in 2021, contrasted with printed counterparts of 418 in the same year), as does the worryingly high number of authors published without adequate contracts in place.

Maximising Solar Panel Efficiency: The DustPV Project

The DustPV project, led by Prof. Ing. Joseph Micallef, aims to determine the optimal timing for cleaning solar panels using innovative sensor technology and weather data analysis. By addressing the challenges of dust accumulation on photovoltaic panels, the project seeks to enhance solar panel performance and contribute to Malta’s renewable energy goals.

Comments are closed for this article!