You can't avoid it. Regardless of whether strong local signals have an effect on health, the reality is you cannot avoid it. How can you prove it isn't the neighbors wifi that makes you sick? And currently, laws do not prohibit ANYONE from installing a 2.4 Ghz or 5.8 Ghz WIFI access point that is 1000mW.
The "smart meters" are significantly less than that. On top of that, a person standing anywhere in the city of Santa Monica, will get thousands upon thousands of different signals blasted through their heads, ranging from cell phone, satellite television, radio stations, air-traffic control, police/fire radio, amateur/truck CB radio, and she can probably find at least 5, and possibly as much as 20 Wifi access points from her couch.
Also interesting to note that the city of Santa Monica has an operating budget (and almost identical cost) of about 500 Million a year. If they were to impose a 20% increase on everything the city receives money from (taxes, tickets, fees, what have you), they would be able to pay Denise Barton in 17 years.
For what it is worth: I have heard of cases where people have an increased sensitivity to radio waves, so I am not discounting the possibility that she is right. But she can't prove what the SOURCE of the problem. If I was her neighbor, I would almost be tempted to buy two 1000mw access points and install them facing her wall.
In any case, if your health IS affected by these radio waves, you will have no alternative but to move. There are plenty of rural communities where your house is far enough from the neighbors house for wireless to be negligible, you can choose not to have a cell phone, and you can maybe even strike a deal with your employed that allows you to work from home part time so you don't have to make the long drive from some small community just north of the Los Angeles mountains in to Los Angeles itself for more than say twice a week.
"I reject your reality and substitute my own!"
Actually, there *are* limits to transmitter power. (effective radiated power is limited by the FCC) Just because it's "unlicensed" spectrum does not mean "unregulated".
(also, boosting the AP power will have little effect without boosting the power of all the remote devices as well. Your iPad won't transmit @ 1W.)