Build plenty of libraries and museums to combat this decay. In order to get the full 70 EQ points from age 5-15, you must have enough to cover the entire population. Also, they must be adequately funded. Otherwise, the same as schools. Libraries can serve a population of about 20,000.
Museums are twice as effective, serve double the population, but cost twice that of a library.
As you can see, the process takes time, maybe 30 to 60 years or more. You can't just place educational facilites and expect the EQ to skyrocket instantly. The kind of EQ you have effects what kind of industries you get. At about 130, industries in the fields of electronics and aerospace will get a boost, but these industries will suffer if your EQ goes under 85. You generally want industries like electronics and aerospace because they pollute less.