Expedition 48 Commander Jeff Williams of Nasa returns to Earth on September 6, 2016, after a five-and-a-half-month mission aboard the International Space Station.
JOHANNESBURG - A decrease in the use of chlorofluorocarbon (CFC) gases is helping to heal the hole in the ozone layer, according to Nasa.
The space agency has been using its Aura satellite to measure the chemical composition of the ozone layer over the Antarctic.
It says a 20 percent decrease in the levels of chlorine in the Earth&39;s atmosphere since 2005 has led to the hole shrinking.
CFC gases in aerosols and refrigeration units were blamed for depleting the protective layer, but they have been banned since 1987.
Susan Strahan, an atmospheric scientist, says the Montreal Protocol banning the production of ozone-depleting substances has been a "great success".
"We know this because we&39;ve been measuring those substances at the Earth&39;s surface since the 1980s, or even before in some cases. So before the Montreal Protocol, ozone-depleting substances at the surface were going up rapidly. Once the protocol was signed and the regulations went into effect, we saw at the surface levels of ozone-depleting substances going down."