The <a href="https://en.wikipedia.org/wiki/Montreal_Protocol" id="mwAts" rel="mw:WikiLink" title="Montreal Protocol">Montreal Protocol</a> comes into force, stopping the use of chemicals contributing to <a href="https://en.wikipedia.org/wiki/Ozone_depletion" id="mwAtw" rel="mw:WikiLink" title="Ozone depletion">ozone depletion</a>.<sup about="#mwt460" class="mw-ref reference" data-mw='{"name":"ref","attrs":{},"body":{"id":"mw-reference-text-cite_note-90"}}' id="cite_ref-90" rel="dc:references" typeof="mw:Extension/ref"><a href="./January_1#cite_note-90" id="mwAt0" style="counter-reset: mw-Ref 90;"><span class="mw-reflink-text" id="mwAt4">[90]</span></a></sup>
<span class="mw-reference-text reference-text" id="mw-reference-text-cite_note-90"><cite about="#mwt457" class="citation book cs1" id="CITEREFAndersenMadhava_SarmaSinclair2012"><a href="./Stephen_O._Andersen" id="mwEBs" rel="mw:WikiLink" title="Stephen O. Andersen">Andersen, Stephen O.</a>; Madhava Sarma, K.; Sinclair, Lani (2012). <a class="external text" href="https://books.google.com/books?id=zuesUPcIOq8C&amp;pg=PA100" id="mwEBw" rel="mw:ExtLink nofollow"><i id="mwEB0">Protecting the Ozone Layer: The United Nations History</i></a>. Earthscan. p.<span id="mwEB4" typeof="mw:Entity"> </span>100. <a class="mw-redirect" href="./ISBN_(identifier)" id="mwEB8" rel="mw:WikiLink" title="ISBN (identifier)">ISBN</a><span id="mwECA" typeof="mw:Entity"> </span><a href="./Special:BookSources/978-1-84977-226-6" id="mwECE" rel="mw:WikiLink" title="Special:BookSources/978-1-84977-226-6"><bdi id="mwECI">978-1-84977-226-6</bdi></a>.</cite><span about="#mwt457" class="Z3988" id="mwECM" title="ctx_ver=Z39.88-2004&amp;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&amp;rft.genre=book&amp;rft.btitle=Protecting+the+Ozone+Layer%3A+The+United+Nations+History&amp;rft.pages=100&amp;rft.pub=Earthscan&amp;rft.date=2012&amp;rft.isbn=978-1-84977-226-6&amp;rft.aulast=Andersen&amp;rft.aufirst=Stephen+O.&amp;rft.au=Madhava+Sarma%2C+K.&amp;rft.au=Sinclair%2C+Lani&amp;rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3DzuesUPcIOq8C%26pg%3DPA100&amp;rfr_id=info%3Asid%2Fen.wikipedia.org%3AJanuary+1"></span></span>