The study published in Science of The Total Environment is a wake-up call for the maritime industry. It’s not just about sulphur anymore—particulate matter (PM2.5) and heavy metals are the new battleground. The findings are clear: wet scrubbers, while effective at reducing sulphur emissions, do little to curb PM2.5 or heavy metal emissions from heavy fuel oil (HFO). This challenges the industry’s reliance on scrubbers as a silver bullet for compliance and environmental protection.
The data speaks for itself. Switching from HFO 2.2 to HFO 0.5—compliant with IMO 2020 regulations—cut PM2.5 emissions by up to 28% and particle number (PN) emissions by up to 58%. Heavy metal emissions plummeted by up to 81%. These aren’t marginal gains; they’re a stark reminder that fuel quality matters. The study underscores that even within regulatory limits, HFO fuels—with or without scrubbers—emit far more PM2.5, PN, and heavy metals than marine gas oil (MGO), hydrotreated vegetable oil (HVO), or ultra-low sulphur heavy fuel oil (ULS-HFOar).
This isn’t just a technical issue; it’s a public health imperative. PM2.5 and ultrafine particles (UFP) penetrate deep into the respiratory system, contributing to cardiovascular diseases, lung cancer, and other health risks. The study’s findings align with broader concerns about air pollution’s impact on coastal communities, where ship traffic is dense. The comparison to road traffic emissions is particularly striking. Marine engines emit more PM2.5 and PN than road vehicles, yet they operate under far looser regulations. This disparity needs urgent attention.
The study also highlights the limitations of current regulatory frameworks. The IMO’s focus on sulphur content has driven progress, but it’s not enough. The lack of direct regulations on PM2.5 and heavy metals is a gaping hole. The findings suggest that even within SECA zones, where sulphur emissions are tightly controlled, HFO use should be reconsidered. Wet scrubbers may reduce sulphur, but they don’t address the full spectrum of pollutants. This calls for a broader regulatory approach that accounts for the complex interplay between fuel type, engine load, and emissions.
The maritime industry is at a crossroads. The study’s results should accelerate the shift towards cleaner fuels like MGO, HVO, and ULS-HFOar. It also underscores the need for further research and innovation in emission abatement technologies. Wet scrubbers are not the end of the road; they’re just one tool in the toolbox. The industry must explore and invest in technologies that can tackle PM2.5 and heavy metals effectively.
The study’s implications extend beyond compliance. They challenge the industry to rethink its approach to sustainability. The findings should spur action from policymakers, shipowners, and technology providers. The IMO and regional authorities must consider stricter regulations on PM2.5 and heavy metals. Shipowners should prioritise cleaner fuels and advanced emission control technologies. Technology providers must innovate to fill the gaps in current solutions.
The study is a call to arms for the maritime industry. It’s time to move beyond sulphur and tackle the broader challenge of particulate and heavy metal emissions. The health of coastal communities and the environment depends on it. The industry must act now to ensure that shipping’s contribution to global trade doesn’t come at the cost of public health and environmental sustainability.