cdtaylor do you work for the Heathrow Propaganda Comms Team?
Without wishing to be rude, what you have written is arrant nonsense. The pollution reduction from less time spent in the stack (if that even happens) is minimal. Likewise noise. Most people affected by noise are NOT hearing noise from the stack. They are suffering extremely loud noise from aircraft on the final descent or from takeoff. To give you an idea, I live 16 miles out from Heathrow, qualify for no noise mitigation payment, yet suffer 90-110db every 90 seconds (with noise rising and falling from this in between -there is never no noise) for 19 hours per day.
Noise blights lives and causes mental health problems. The pollution we already suffer ends thousands of lives prematurely each year, causes serious health conditions like asthma, heart attacks, strokes and dementia, causes kids to lack concentration in class and causes autism in some children. That is just a few of the adverse effects. There are more.
The mitigation you mention is extremely small beer in comparison, if it is true at all. If you do not work for Heathrow, might I suggest you acquaint yourself with some unbiased information? There is plenty to be had on the net.