This year seeks 25 new participants, for a total of 138, and 32 new pavillions, for a total of 328, as well as 10 more publishing brands, for a total of 636 publishers and brands, Bruno Pacheco, the secretary-general of the Portuguese Association of Publishers and Booksellers (APEL), said.

"There are four adjectives that describe this book fair: more, better, greener and more family-oriented," said Pacheco, who also noted that the number of pavillions has grown by more than 11% and the number of participants by some 20 percent.

In all, the fair will cover 2,000 more square metres this year, much of it grassy areas.

New participants this year include famous Lisbon bookstore Ler Devagar, the Fundação EDP arts foundation and its Lisbon-based Museum of Art, Architecture and Technology (MAAT), Portu’s Fundação Serralves and the Museu Berardo momden art collection.

Another novelty is the spread of "publishers’ squares" – clusters of pavillions all from the same publishing group – as has already been trialled by Presença/2020 and Leya/Porto Editora, and which this year may see Relógio d’Àgua and Almedina appearing together.

On green spaces – with the fair taking over the centre of the park, whose railings are to be removed for the purpose and where lounge areas are to be set up - Pacheco stressed that this year’s will be a "greener" fair in several senses, because this year's theme is environmental sustainability.

Among new departures are the introduction of reusable paper bags, in partnership with paper manufacturer Navigator Company, which is to distribute 60,000 of them.

On the catering side, utensils will be disposable but biodegradable, while throughout the fair instead of the 1,000 sq m of carpeting of previous years there is to be recyclable flooring made from 1,800 used tyres, similar to that used for children’s playgrounds.

A partnership with Lisbon’s Universidade Nova has also been established to assess the environmental measures with a view to replicating them in future.

As for the programme, the APEL secretary-general noted that 1 June, Children’s Day, there is to be a children's stories reading marathon, and also a show-cooking event for kids with a workshop for ‘mini-chefs'.

On 7 June the winners of the ‘2019 Favourite Bookshop’ public vote is to be announced, in an initiative organised by APEL.

Last year’s Lisbon Book Fair was visited by 492,000 people.