Weather conditions are the main driver in Malta’s air pollution with meteorology playing a key part in determining the quality of the air we breathe, according to experts.

Describing meteorology as an “often underestimated” factor, Michael Nolle, ambient quality and waste manager at the Environment and Resources Authority, told Times of Malta that Malta’s air quality is strongly affected by weather events such as high temperatures, horizontal winds and cloud coverage, with each having a clear impact on different types of air pollutants.

Nolle’s views raise concerns over the longer-term impact that climate change and increasingly frequent heatwaves may have on Malta’s air quality.

ERA says it has started to see early indications of changing trends over the past few years, but it is too soon to tell whether this is driven by changes in Malta’s climate.

Levels of ozone higher during warm spells

Likewise, academic and urban air quality expert Mark Scerri says that further research is needed to understand whether changing temperatures are having any effect on Malta’s air quality.

International research shows that levels of ozone, a pollutant known to worsen respiratory illnesses, are higher during warmer spells, with high pressure, drier conditions and weak winds causing ozone to accumulate in the stagnant air. On the other hand, rainfall and strong winds help clear the atmosphere of dust particles and particulate matter, which are some of the heaviest pollutants in Malta.

The UN Environment Programme calls air pollution and climate change “two sides of the same coin”, while the Global Heat Health Information Network says that “projected increases in temperatures and more frequent heatwaves could increase ambient air pollution levels”.

Traffic, Saharan dust and sea salt – Malta’s biggest pollutants

A 2018 study found that over a quarter of PM2.5 pollution in Malta, microscopic particulate matter under 2.5 micrometres in diameter, is caused by road traffic, making it one of the most prominent causes of air pollution in Malta.

PM2.5 and the larger PM10 air particles are both heavy contributors to Malta’s air pollution. Both are invisible to the naked eye, with even the larger PM10 particles being seven times smaller in diameter than a single human hair. These microscopic particles pose a health risk by entering people’s respiratory systems and even bloodstreams.

Particles larger than PM10 pose less of a health risk, as they can often be filtered out by the body’s natural defences, such as a person’s nasal hair and throat.

ERA officials say that particulate matter spikes at rush hour when roads are busiest, and mid-afternoon during the rush of cars going to pick children up after school. This is worsened by the fact that Malta’s fleet of cars is significantly older and less green than that of most other EU countries.

Malta’s fleet of cars is significantly older and less green

Experts say that several issues with Malta’s air pollution stems from natural pollutants over which we have little control. A study carried out by Scerri found that almost a third of all PM2.5 particles are natural, a combination of Saharan dust and sea salt spray from the Maltese coast.

Likewise, according to ERA officials, Saharan dust and sea salt make up some 55% of the coarser PM10 particles in Malta, similar to levels detected in other Mediterranean islands such as Cyprus and Crete.

A further quarter of PM2.5 emissions consist of ammonium sulphate which, ERA say, Malta also has little control over, since they are mostly blown in from agricultural land overseas or the result of shipping emissions.

Construction dust and fireworks, often believed to be prime contributors to Malta’s air pollution, are less of a health hazard than we often think, according to ERA officials.

Only 13% of construction dust is under the size of PM10, meaning that much of it, although still deeply unpleasant, can be prevented from entering the respiratory system. Nevertheless, ERA say, despite this relatively low number there is still a cumulative effect at play, where people living close to multiple construction sites are likely to suffer ill effects.

Meanwhile, fireworks have been found to contribute around 3% of all PM2.5 particles in Malta’s air.

Shift to electric vehicles is ‘not a silver bullet’

Particles generated by the wear of car brakes and tyres are a major contributor to Malta’s air pollution. Photo: Chris Sant Fournier

Vehicle emissions only form a small portion of air pollution caused by road traffic, with a recent study finding that exhaust only makes up some 13% of particulate matter pollution caused by road traffic.

The overwhelming majority of particulate matter pollution caused by vehicles is the result of what researchers call “non-exhaust contributions”, such as the friction caused by car tyres and brake pads when cars decelerate, as well as particles from the road surface.

The levels of non-exhaust contributions are believed to be even higher among electric vehicles, which are frequently heavier than their fuel-powered counterparts. Studies have shown that pollution linked to vehicle emissions, such as PM2.5 and nitrogen oxides have decreased since 2008, while particulate matter caused by road, brake, tyre and clutch wear have increased with the higher number of cars on the road.

This suggests that shifting the car fleet to electric will do relatively little to tackle the key driver of Malta’s vehicle pollution.

ERA officials say that electric vehicles, while beneficial, are not a silver bullet.

Although adopting electric vehicles cuts down on gaseous emissions such as nitrogen oxides, carbon monoxide and benzene, more needs to be done, they say, to reduce the number of cars on the road altogether, pointing to the fact that the reduction in emissions brought about by the “slow” exit of older cars and introduction of electric vehicles is being offset by the sheer increase in cars on the road.

Recent NSO data shows that 58 new cars are introduced to Malta’s roads every day. Electric vehicles only make up 3% of Malta’s total vehicle fleet.

ERA officials point to plans for connected and segregated cycling lanes across the Grand Harbour area as an example of an initiative that could lead to more people ditching their cars in favour of cleaner modes of transport.

The feasibility of several other measures, such as low-emission zones in which the use of higher-polluting vehicles is restricted, is also being studied.

Air pollution levels lower than before COVID

ERA officials say that, on the whole, air pollution levels are yet to increase to the levels they were at before the pandemic. Some pollutants, such as nitrogen dioxides, dipped by half in key traffic areas such as Msida during lockdown periods in 2020 and 2021. Pollutant levels have crawled back up since then but remain under their pre-pandemic peaks. ERA officials say this might be a reflection of the more widespread adoption of remote working practices.

More broadly, ERA says, air pollutant levels have decreased for the most part over the past 15 years, with technological and engineering improvements leading to most heavy metal pollution being all but eradicated. Meanwhile, the level of several other pollutants has remained stable.