Introduction:
The OCS is an activity carried out to facilitate the transit of people residing in Europe who travel on summer vacations to their countries of origin in North Africa. Foreign Health (FH) ensures that the facilities of the ports/ ships involved have adequate hygienic and sanitary conditions, and respond to health events that could pose a risk to public health.

Methods:
Descriptive study based on the data from a survey applied in the nine FH ports assigned to the OCS. Basic calculations of frequencies and percentages were carried out for univariate analysis.

Results:
3.2 million passengers were registered. Thirty-three ships took part, making 11084 calls at nine ports. All the ships were inspected before the beginning of the operation. Thirty-nine Ship Sanitation Certificate SSC were reviewed and 15 Sanitation Control Exemption Certificate (SSCEC)/Ship Sanitation Control Certificate (SSCC) were issued (Figure 1).

Conclusions:
The OCS is an event that mobilises a significant number of travellers every year, who converge in the maritime ports of southern Spain. This concentration of people/vehicles during the summer season poses a significant risk to public health in the absence of prevention, control and timely response measures to the problems identified.