Exchange rate: OECD (2015a), "PPPs and exchange rates”, OECD National Accounts Statistics (database), http://dx.doi.org/10.1787/data-00004-en (accessed 30 June 2015), Minimum wage: CONASAMI (2015), “Tabla de salarios minimos generales y profesionales por areas geograficas”, Comision Nacional de los Salarios Minimos, www.conasami.gob.nix/t sal mini prof.html (accessed 7 April 2015). This represents a high cost to public health, and has a negative effect on the productivity, competitiveness and attractiveness of the metropolitan zone. The OECD’s work on cities and climate change has observed that if their current pollution trends continue, even cities such as Chicago, Los Angeles, New York, Osaka, Paris, Seoul and Tokyo are at risk of losing economic attractiveness (OECD, 2010). In the international scene, Mexico is committed to reducing 30% carbon emissions by 2020 and by 40% by 2030 (a combined effect of reducing CO2 emissions by 70% and greenhouse gas emissions by 36%) compared to the emission level in 2012.