Well, I was going to respond in the negative about the rise in IQ levels as, based on my experience of the graduates coming into the workplace these days, I felt the reverse to be true.
However, I thought I'd do a little digging before commenting and the first thing I found with a quick google on "average IQ levels trends" was this:
http://www.wired.com/wired/archive/13.05/flynn.html.
So I can only assume that what I'm observing about the stupidity and lack of knowledge in new graduates is down to a failure in the education system rather than a fall in the students innate mental horse-power (altho' I'll stand by my assertion that it is true that degrees have been made too easy these days).
Anyhow, on-topic, the pollution issue is a very serious one because of the climatic trends that it can emphasise (as well as incidental health issues).
The problem is that by the time you've realised that there
is a problem, it's too late to do anything about it. Natural processes have a lot of momentum and once they get going it's rather difficult to persuade them to stop, particularly if they're ones that have 'break points' where a sudden change occurs after a long period of apparent equilibrium.
Regardless, I wouldn't allow myself to worry too much about climate change and pollutions role in that.
The real 'threat' hanging over us in the near future is the magnetic polar inversion that is on it's way. It's already showing signs of having started and the 'radiation shielding' of the planet is on the wane.
It's only a slow process as we measure 'normal' happenings but in geological terms it's one of those 'break point' events and could complete in mere decades (tho' centuries has a less 'apocalyptic' ring to it, if it does turn out to be that slow then it's even worse because it takes longer for the Earth's magnetic field to sort itself out).
I reckon that this is the event that was the inspiration for that rather splendid film "The Core" (starring the rather splendid Hilary Swank

). Altho' the dire prognoses voiced there were somewhat inflated, it is the case that if the magnetic field strength falls away then we all start getting a somewhat unhealthy exposure to radiation. Plus, electrical devices start having a tough time of it if they're not shielded. What is particularly vulnerable is the electricity generation and distribution network - if that gets fried by a solar flare then it's adios Advanced Technological Society ...