ARTICLE 
COMMUNICATIONS EARTH & ENVIRONMENT | https://doi.org/10.1038/s43247-023-01050-7 
A 
— = Baltic Sea inspections a North Sea inspections 
= Baltic Sea non-compliance a North Sea non-compliance 
— SECA inspections 
z SECA non-compliance 
— Outside SECA inspections 
a Outside SECA non-complance 
"000 ı 
12% 
5.000 
10% 
5.000 
„4,000 
5 
3.000 
E 
72000 - 
* 8% 
„— 
3 
SS 
D 
3 
= 
| 6% 
nr 
x 
3 
3 
s 
„4% 5 
000 
2% 
3 
2015 
a 3 ed WA, 
2016 2017 2018 2019 2020 
Year 
+ 0% 
2021 
2022 
3 
zz Baltic Sea fuel samples a North Sea fuel samples zz SECA fuel samples a Outside SECA fuel samples 
= Baltic Sea non-compliance a North Sea non-compliance —— SECA non-compliance — Outside SECA non-complance 
800 
- 10% 
ı 600 
% 
L 8% 
1 400 
4.200 1 
- 7% 
u 
> 
1.000 ] 
„6% © 
= 
S 
L5% & 
L 4% 
N 
„3% £ 
2% 
“= 800 
600 
400 
200 
1% 
7 
—+ 0% 
2016 
2017 
2018 
2019 2020 
2021 
2022 
Year 
Fig. 5 Overall non-compliance results for the EU. Non-compliance for EU MS in the North Sea and Baltic Sea based on Thetis-EU data on documentary 
inspections (A) and fuel sample analysis (B). 
contrast, the results of the inquiry on NO, enforcement and legal 
follow-up within the BA were disappointing (Fig. 4B). Only two 
BA CPs have reported NO, infringements and only one BA CP 
has imposed a penalty for a NO, violation. Most of the other BA 
CPs are currently not enforcing NO, regulations nor collecting 
data on the results of the NO, inspections at the time of 
publication. This demonstrates that enforcement of NO, regula- 
t.ons by BA CPs is currently lacking. Upon examining the limited 
available NO, inspection data, it becomes evident there has not 
been a decrease in violations since the NECA was implemented, 
but rather, an increase. However, the scarcity of data does not 
allow statistical analysis or strong conclusions to be drawn about 
compliance rates within the BA. 
Results within the EU. Upon examining the data on sulfur 
inspections and non-compliance rates within the EU, similar 
patterns were observed within the Baltic Sea and North Sea ECA 
as within the BA (Fig. 5A). In the wider SECA, in total 110,657 
documentary inspections were conducted. The annual amount 
showed a slight increase since entering into force in 2015, with a 
velatively stable trend over the entire period, except for a small 
decline in 2020. This increase was mainly a result of the increased 
aumber of inspections by the North Sea ECA countries, while the 
Baltic Sea countries had a more stable number of conducted 
nspections throughout the entire period. The non-compliance 
rate based on documentary inspections followed a similar trend 
as the number of infringements in the BA. However, it is 
ımportant to note that this pattern is largely influenced by a 
noteworthy reduction in non-compliance in the North Sea, while 
the reduction in the Baltic Sea is less pronounced. Also, when 
looking at the compliance results outside the SECA, the reduction 
was less pronounced. The overall non-compliance rate in the 
COMMUNICATIONS EARTH & ENVIRONMENT | (2023)4:391 | https: //dol.0rg /10.1038/s43247-023-01050-7 | www.nature.com/coammsenv