Complex sentence: It is theorized that in 1952 in London, the nitrous dioxide and sulfur dioxide combined with fog rather than humidity; larger droplets of water diluted the acids, inhibiting the reaction to stop neutralization.
Split into simpler sentences: It is theorized in London in 1952 that the nitrous dioxide and sulfur dioxide combined with fog rather than humidity. This means larger droplets of water diluted the acid which inhibited the reaction to stop neutralization.