University of Malta experts have said MPs must understand “holistically” the effects of policies to reduce car and transportation emissions.
A study on changes in car emissions on Maltese roads during the COVID-19 lockdown, and associated health effects in Malta, found a reduction of the regulated pollutant nitrogen dioxide in air, but caused surface ozone levels to rise.
Despite the good news on reduced emissions thanks to less cars on the road during the pandemic, the study’s scientists told MaltaToday that rising ozone exposure can trigger various responses such as chest pain, coughing, throat irritation, and airway inflammation.
“It can reduce lung function and harm lung tissue. Ozone can worsen bronchitis, emphysema, and asthma, leading to increased medical care,” said contributor Dr Sara Fenech.
Elevated exposure to ozone can affect sensitive vegetation and ecosystems, including forests and parks, harming sensitive vegetation during the growing season.
The Department of Chemistry at the University of Malta used a machine-learning algorithm to predict business-as-usual results, compared to the reduced traffic on roads in Msida during the pandemic’s soft lockdown. Lead researcher Dr Noel Aquilina said the study found a decrease in monthly mean nitrogen dioxide concentration of up to 54% in Msida.
But in contrast, the monthly ozone levels were up to 61% higher in the same area, compared to a business as usual scenario in Msida.
“Our results highlight the favourable effects of decreasing traffic-related emissions on nitrogen dioxide concentrations; however, we also note increases in other pollutants for example Ozone concentrations which especially in the short-term can lead to various adverse health effects,” Aquilina said.
So in future, where nitrogen dioxide emissions are targeted to decrease to levels as observed during the pandemic, the burden to control ozone levels will also increase.
Aquilina policies should focus on limiting ozone precursors, such as volatile organic compounds, which are very limited “and not routinely measured across Europe.”
Fenech said that one of the main takeaways form the study is that if you alter one pollutant, you will inevitably modify the chemical balance in the atmosphere.
“Nitrogen dioxide changes have favoured other reactions, and therefore have changed the balance in the atmosphere. So I would presume – and of course this needs to be studied further – that if more electric cars were introduced, the chemical balance is similarly going to shift especially in traffic sites.
“What we are saying here is, we can’t create policies which target one pollutant. We need to look at the atmosphere holistically to understand the complex chemistry that happens. We also have to look at it spatially: what happens in Msida might not be what happens in Għarb,” she said of the sleepy Gozitan village.
“In fact, we know that the impact is not going to be the same across our islands, so their needs to be targeted studies to make sure the best mitigation strategies are implemented.”
Aquilina also adds that a step forward for the country would be for public funding to carry out sampling and chemical analyses of specific conurbations where urban chemistry is challenging. “We would understand certain things better, which would give additional tools to the government to draw up better policies associated with a preventive rather than a curative approach, when dealing with the exposure to pollutants.”