Says the guy who doesn't understand anything about science.
"That is the problem,all of these scientists are doing what they do which is really just guessing..."
To be fair, I don’t think it was challenged, at least not from my perspective. I was more questioning why it was the biggest deal at the time only to no longer hear anything about it some years later. I recall the same regarding “acid rain”.
The video he posted tried to claim that there was never any ozone depletion, which was definitely challenging the science behind the effect chlorofluorocarbons (CFCs) cause on ozone levels.
The reason you rarely hear about the ozone hole and acid rain problems anymore is because those two problems have been nearly rectified through very successful environmental legislation.
The ozone hole problem was caused by CFCs being emitted from aerosols. CFCs would diffuse into the stratosphere and destroy the ozone. In the late 80's CFCs were heavily restricted at the Montreal Protocol, and not long after European countries banned them, and then the Montreal Protocol was strengthened in the early 90's to fully ban CFCs by 2000. The ozone levels have been recovering since the mid 2000's, and are projected to recover to 1970's levels by the end of the century. However, we might start hearing about ozone issues again, as increasing emissions have been measured to be coming from Asian countries in the past year.
Acid rain on the other hand is mainly caused by sulphur dioxide and nitrogen oxide (NOx) emissions. In the USA the majority of the sulphur dioxide came from the combustion of coal. The solution to this problem was The Clean Air Act Amendments in 1990. They placed a cap and trade system on SO2 emissions for power generation facilities. The emissions dropped faster than expected, and at cheaper costs than expected. This was achieved through the use of scrubbers and other SO2 cleaning systems. NOx emissions had to be reduced as well, which was performed through low NOx-burners, which generally work by reducing the flame temperature, as the production of NOx is directly related to flame temperature (thermal NOx).