A review of 67 studies shows the IMO's 2020 sulphur cap significantly reduced ship-related air pollution, improving air quality in port regions.
A systematic review of 67 studies found that the International Maritime Organization's 2020 sulphur cap has led to sharp reductions in ship-related air pollution, reported Basel's scholarly MDPI, Molecular Diversity Preservation International.
The regulation, which limits the sulphur content of marine fuels to 0.50 per cent, has been linked to lower emissions of sulphur dioxide, sulphate aerosols, and particulate matter. Researchers said this has improved air quality in major port regions and reduced population exposure to harmful pollutants.
The review also highlighted continuing challenges. These include emissions of ultrafine particles and volatile organic compounds, secondary pollutant formation, and contamination from scrubber washwater discharge.
While the decline in sulphate aerosols has reduced acid deposition, it has also lessened their cooling effect, contributing to positive radiative forcing.
From a health perspective, reductions in PM2.5 exposure are expected to lower risks of respiratory and cardiovascular disease, though few epidemiological studies have yet confirmed these benefits under real-world conditions.
The review noted that compliance strategies such as scrubbers and very-low-sulphur fuel oils have introduced environmental trade-offs, raising concerns over marine pollution and fuel quality.
Overall, the evidence suggests IMO 2020 has cut sulfur-related pollution, but researchers urged caution in attributing health outcomes solely to the regulation, given concurrent factors such as the COVID-19 pandemic and geopolitical disruptions.
