Negative Ions Chart

Here is a list of different places with their value of negative ions per cubic centimeter, from the chart you can see that natural places like waterfalls have a magnificent number of negative ions per cc.

Places & Conditions of Negative Ions (per C.C)

WATERFALLS
25,000 - 100,000

CAVES
5,000 - 20,000

MOUNTAINS
700 - 5,000

KINOHIMITSU
800 - 1,500

COUNTERSIDE
700 - 750

INDUSTRIAL CITY
250 - 750

NORMAL HOUSEHOLD (windows open)
250 - 500

INSIDE AEROPLANES
20 - 250

OFFICE BUILDINGS (with Air-Con)
0 - 250

SMOKEY INDOORS
0 - 100