Emission rates of the ozone-depleting chlorofluorocarbon CFC-11 are no longer in decline (see S. A. Montzka et al. Nature 557, 413–417; 2018). We suggest that Asia’s construction boom could be part of the cause, by provoking a rapid increase in the unauthorized production of this chemical for building-insulation materials.
The 1987 Montreal Protocol resulted in a global ban on production of CFC-11. However, production has resumed since 2013 in some parts of China (see go.nature.com/2mj8ijg), coincident with the country’s increased demand for insulation foam (C. Yang et al. Energy Build. 87, 25–36; 2015). The same could be happening elsewhere, so other offenders urgently need to be identified.
If the fragile stratospheric ozone layer is to recover, the production and disposal of building-insulation materials must be more effectively monitored and managed, backed by stricter legislation. The development of low-cost alternatives to ozone-depleting substances for building materials is also a priority, given the pace of urbanization in China and other nations.
Nature 560, 167 (2018)