Construction and the increasing volume of traffic are producing more dust in the air that contains chemicals harmful to health, a leading atmospheric scientist has warned.

Noel Aquilina, a senior lecturer at the University of Malta, said these large particles are not being adequately monitored.

Yet, they have the tendency to be more toxic than fine particles due to the “complex mixture” of the chemicals they are made of.

Due to our typically dry weather, these coarse particles make up roughly 58 per cent of the particulate matter in the air, while the remainder is made up of fine particles.

The increase in coarse particles may be attributed to two major activities, says Aquilina: the ever-growing number of vehicles on the road and construction activity.

Moving vehicles generate particles from tailpipe exhaust, which are typically fine in nature. But they also produce other particles, termed non-exhaust emissions, that contain a mix of harmful chemicals.

This occurs through brake wear, which produces particles full of metals; tyre wear, which generates particles full of zinc and organic compounds; road wear, consisting mainly of organic compounds; and re-suspended dust generated when vehicles catapult all these particles back into the air, mainly impacting areas very close to the road.

Multiple health problems

Respiratory specialist Stephen Montefort said the larger particles – produced mainly from quarries, construction activity, dust in the roads and fireworks – are still small enough to cause multiple health problems.

“Most obvious are respiratory problems with worsening and exacerbation of rhinitis, asthma, chronic obstructive pulmonary disease and bronchitis,” he said, adding that they are also associated with stroke and heart disease.

Visible dust, he said, could be irritating to eyes, skin and nose, causing coughing, breathlessness, wheezing and an increase in phlegm production. 

The dust can also contain elemental heavy metals which can likewise be harmful, he added.

Time for authorities not to rely on a generic air quality monitoring network

Research that has been carried out by the University of Malta showed increases in childhood asthma and allergic rhinitis in built-up areas full of construction and traffic.

Particulate matter ranges in size and can be very problematic because the finer the particles, the deeper they penetrate into the respiratory tract, ending up in the lungs.

Coarse particles are the relatively large airborne particles mainly produced by the mechanical break-up of even larger solid particles.

They have an aerodynamic diameter ranging from 2.5 to 10 microns, about one-seventh the thickness of a human hair.

This distinguishes them from the smaller airborne particulate matter referred to as fine (PM2.5).

An incomplete picture

Aquilina said Malta is doing relatively well when it comes to the levels of particles that need to be reported to the European Commission under the EU’s Air Quality directive. 

However, this does not provide the complete picture of the island’s air quality.

A recent study carried out by the Department of Chemistry (Fenech & Aquilina, 2020) analysed all the data collected from the Environment and Resources Authority’s air quality monitoring station network between 2008 to 2017. The network is located in Għarb, Attard, Kordin, Żejtun and Msida.

Results showed that, when looking at pollutants regulated at European Union level, Malta was doing well. In the case of fine particulate matter (PM2.5) the annual average concentration stood at approximately 12 µg/m3 (12 micrograms of gaseous pollutant per cubic meter of ambient air).

This was below the annual limit of 25 µg/m3 set by the air quality EC directive.

In the case of large particulate matter (PM10), the European Union sets the annual limit at 40 µg/m3. In all stations, the annual average was 25 µg/m3, with only Msida hitting the limit at 40 µg/m3.

“In all fairness, with respect to the directive, we are managing to keep up with the limit values for both PM2.5 and PM10,” Aquilina said.

But the measurement of particulate matter or other regulated pollutants alone did not necessarily give the true picture of the complex atmospheric chemistry, nor the implications of the exposure to other pollutants and their effects on health, he said.

“It is time for the health and environmental authorities not to rely on a generic air quality monitoring network.

“Funding a long-term research programme, to establish the real links between specific areas, activities and groups of people… would be highly beneficial,” he noted.

“Such data not only helps in understanding certain health trends but also to understand the local atmospheric chemistry, in particular to address mitigation policies associated with improving air quality when our urban fabric is changing so fast.”