## 1 Introduction
### Maritime Emissions and Their Effects
#### 1.1.4 Italian Ports  
Data about ship activity and emissions in Italy's ports are available from a variety of sources, but the lists of ports in each data set vary considerably. Thus, although it is possible to develop summaries of the overall system of ports and detailed data about maritime activity and emissions in many individual ports, it is not possible to present a single comprehensive table with data for all indicators for all of the ports. What follows, then, is a series of tables from a variety of sources, which altogether add up to a compilation that allows observations about the ports in relation to the focal concerns of the paper [43; 44; 45; 46; 47; 48; 49; 50; 51; 52; 53; 54]. The principal international ports of Italy are organized into 15 regions, each with a core network port and most of the regions with one or more of 18 additional ports. Altogether, the study focuses on the 33 international ports in the formally organized Italian national port system, with their highly varying sizes and mixes of types of ships. In terms of the aggregate indicator of'vessels in main ports,' each year over the period from 2013 through 2018, Italy had the second largest number in Europe after Greece; Italy has been the leading'seaborne passenger' country in Europe for several years. In 2018 Italian ports processed nearly 85 million passengers on cruise ships and ferries combined. Most of these were ferry passengers [55]. Cruise ship traffic is, of course, economically significant to the ports and is experiencing increasing political attention because of its conspicuous physical presence in ports and along coasts. Cruise ship ports in Italy are particularly noteworthy for the volume of activity in them, especially in the context of the Mediterranean Sea. Italian ports' cruise activity equaled about 40% of all Mediterranean cruise traffic in 2019; altogether, Italian ports processed 23.8 million cruise passengers and 8959 port calls in 2019 [56]. Four of the Italian ports were among the top ten in the Mediterranean area as measured by number of passengers and port calls. Civitavecchia, which serves Rome, was second in the Mediterranean, after number 1, Barcelona, Spain. The specifics for the top four Italian ports are in Table 3, where large increases from the previous year are evident. Note that a confusing feature of 'passenger' counts is that passengers are usually counted twice on each trip, first when embarking and then when debarking, as in Tables 3 and 4[32; 55]. However, there are also data sets where this 'double counting' is avoided. Thus, while some data sets report on the order of 20 million cruise passengers per year in Italy, others report about half as many. There was significant growth in the cruise traffic from 2018 to 2019 before the coronavirus hit Italy in early 2020. In 2018, Italy was first in Europe in the number of cruise passengers passing through its ports, ahead of Spain and Germany [32]. The economic significance of the cruise ship industry in Italy is further indicated by the fact that Italian cruise shipbuilder Fincantieri is the largest in Europe. As of late 2020, the previously planned merger with French cruise shipbuilder Charntiers de l'Atlantique seemed destined to be discontinued because of EU Commission doubts about competition policy issues and French government hesitations about other issues [43]. However, shipping traffic in Italian ports is dominated by non-specialized cargo, as indicated by numbers of vessels and by gross tonnage [32]. Container ship activity in three Italian ports put them in the top 20 in Europe in recent years during 2008-2018, Gioia Taro (8 th), with 4.0 million TEUs in 2018, Genoa (13 th) with 2.6 million, and La Spezia (19 th) with 1.7 million. As for total freight handled in Italian ports over the period 2013-2018, only Trieste (12 th) and Genoa (17 th) ranked in the top 20 in Europe. At the top among European ports were Rotterdam, Antwerp, and Hamburg with 14, 11, and 9 million TEUs, respectively.