One in five research papers published in 2008 are now freely available on the internet, according to a recent survey (PLoS ONE, 5(6), e11273; 2010).

Bo-Christer Björk and colleagues at the Hanken School of Economics in Helsinki, Finland, manually checked the availability of 1837 articles, randomly sampled from 1.2 million articles in Elsevier’s Scopus database.

Of those, 8.5% were free to view at publishers’ websites – the so-called ‘gold’ open access (OA) route – of which one in four had been made free because authors had published in a subscription journal but paid to open up the article.

Another 11.9% could only be found on authors’ websites or in repositories – so-called ‘green’ OA. Repositories set up by universities or institutions accounted for one in four of these green OA articles; while 43% of them could be found in subject-based repositories such as ArXiv and PubMed.

Breaking down the articles by discipline (see chart), the researchers found that earth sciences had the highest overall open access (OA) share, with 33%, while chemistry had the lowest, with 13%.

In life sciences, the majority of open access (OA) articles were gold, free at publishers’ websites. But in other disciplines, most of the OA articles were green, only available on authors’ websites or in repositories.