Compliance & regulations in shipping
Emission compliance in shipping continues to evolve as global and regional regulations tighten to reduce environmental impact and protect public health. Shipowners and operators must ensure that vessels comply not only at the point of certification, but throughout real application operation.
Meeting regulatory requirements today goes beyond installing compliant technology. It requires the ability to monitor, verify, and document emissions – ensuring that vessels operate within permitted limits under all conditions, and in some regions, such as under U.S. EPA regulations, through continuous emissions monitoring and reporting.
The regulatory landscape
MARPOL Annex  VI, established by the International Maritime Organization (IMO), together with the associated NOx Technical Code, defines the global framework for controlling air emissions from vessels. It sets limits on sulfur oxides (SOx), nitrogen oxides (NOx), and other pollutants, while also establishing requirements for energy efficiency and emissions reporting.
Under this framework, NOx emissions are regulated through Tier-based standards, with the strictest Tier III limits applying to vessels operating in designated NOx Emission Control Areas (NECAs). Compliance in these areas requires engines to operate within significantly reduced emission thresholds, often supported by advanced emission-reduction technologies.
The IMO regulations provide a comprehensive framework for emissions compliance, addressing key atmospheric pollutants and supporting more sustainable maritime operations.
NOx compliance largely relies on engine certifications and assumptions
Traditionally, NOx compliance has relied on engine certification, design approval, and assumed system performance. However, increasing regulatory port state control inspections are shifting the focus toward operational compliance.
Authorities are placing greater emphasis on:
- Verified emissions data rather than theoretical assumptions
- Continuous monitoring across different operating modes
- Transparent and auditable reporting
This shift highlights the growing need for objective, data-driven compliance verification.
Compliance to IMO Global Sulphur Cap 2020
Under IMO MARPOL Annex  VI, the Global Sulphur Cap limits sulphur emissions from vessels by requiring:
- Maximum 0.50% m/m sulphur content in fuel globally
- Maximum 0.10% m/m within Emission Control Areas (ECAs)
As an alternative to low-sulphur fuels, vessels may use approved equivalent solutions such as Exhaust Gas Cleaning Systems (EGCS), commonly known as scrubbers. These systems enable continued use of higher-sulphur fuels while ensuring that sulphur oxide (SOx) emissions remain within regulatory limits.
Continuous Emission Monitoring Systems (CEMS) provide real-time data and documented evidence, supporting both regulatory compliance and efficient scrubber operation.
Need help navigating regulatory compliance?
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