1. Negative ions are produced naturally from cosmic rays, waterfalls, oceans, and thunderstorms.
2. Don’t buy salt lamps. Contrary to what they promise, they don’t actually produce negative ions.
3. An air purifier with ionizer function does produce some negative ions, but also ozone, or what you will call smog in a city.
4. Despite studies showing some correlation between negative ions and their impact on our mood and health, it must be noted that those studies which gave this outcome either had methodology issues, small sample sizes, or are flawed one way or another.
Taken as a whole, it is not possible to conclude that negative ions are indeed better for our health.
What is proven to work is exercise, so get your butt out there and start working out.
Source video provided here.