'Expo is the event that promised jobs and wealth, but in fact led to the exploitation of voluntary labor, with an excessive load on overtime,' she said, adding that many in Milan were unhappy about the event. 'We are expecting tens of thousands of people,' Valentina Gazzara, a member of Off Topic, a group involved in the NoExpo movement, told CNBC via email. More demonstrations are expected on opening day, with a group known as NoExpo planning a procession through central Milan to coincide with May Day labor marches. On Thursday, student protesters marched through the city the words 'No Expo' were spray painted onto shop fronts, while policemen in riot gear patrolled the streets. 'The equity market in Italy is not going to be effected at all by Expo,' he told CNBC. Italian stocks won't get much of a boost either, according to Marco Elser, a partner at Italian investment banking firm Advicorp. The Milan Chamber of Commerce, meanwhile, expects the event to generate 191,000 new jobs for Italy вЂ“ another figure which the professor said was optimistic.ДЇrancesco Galietti, CEO of Rome-based political risk consultancy Policy Sonar, told CNBC that the Expo would 'certainly' contribute to Italy's GDP growth, but noted that its impact would be dwarfed by the Catholic 'Holy Year of Mercy,' which will run from December 2015.

Officials expect gross domestic product (GDP) to increase between 10-14 billion euros ($11.2-15.6 billion), Borri said, but although this takes into account additional infrastructure, it doesn't include funding costs and any 'crowding out effects' вЂ“ when extra pubic spending hits the level of private expenditure.

'The official estimates are very optimistic,' Nicola Borri, assistant professor of economics at Rome's LUISS Guido Carli university, told CNBC by email.

Milan world exposition