A record three million tourists are expected to visit Dublin this year and they will spend over £500 million in the city and region.The 1998 estimates were issued yesterday by the Dublin Chamber of Commerce, whose research indicates that tourism figures for Dublin will increase by up to 15 per cent on 1997. The chamber said this level of activity sustained almost 30,000 jobs in the city.The estimates are based on market figures for the first quarter of this year compared to the same period last year. The statistics show an increase of 11.3 per cent in tourists visiting the capital.Most visitors are from the UK and US, with estimated increases this year of 10.2 per cent and 20 per cent. The growth in tourists from Europe is expected to remain at a steady 7 per cent, with other sectors growing at more than 20 per cent for 1998.Hotel, retail and transport industry sources also indicated increases in hotel numbers, according to the chamber. Tour companies and Dublin Bus are showing a huge increase of 60 per cent in passengers for city tours, 70 per cent of them being UK tourists."Tourism is now a major player in the economy of the city," Mr Ciaran Conlon, the chamber's research executive, commented. "The challenge now for the city and its agencies is to manage this growth. This can be achieved by attracting off-peak specialist events to the city, providing basic infrastructure for large international sporting occasions and finally building the national convention centre."A separate report issued by Aer Rianta shows that a record 6.6 million passengers were handled by the airports at Dublin, Shannon and Cork during the first six months of the year, Arthur Quinlan writes.Dublin had more than 5.2 million passengers, an increase of 12 per cent, and transatlantic figures showed a 22 per cent increase, to 274,395. Shannon, with 786,000 passengers, had an increase of 3 per cent. Its transatlantic figures grew by 7 per cent to 216,086, while there was a decline in European numbers. This, the report said, was due to "a weakness in the inbound charter business from Germany and France".Cork Airport handled more than 570,000 passengers, an increase of 6 per cent. Aer Rianta states that with the introduction of new services and an increase in frequencies, the level of growth should be sustained this year.