The standard for chlorine in pools is 1-3 ppm.
The standard for chlorine in spas is 3-5 ppm.

Most people can not detect by feel, taste or smell free chlorine in water at levels up to 15 ppm.
The EPA guideline is swimmers may enter the water when free chlorine levels are below 5.0 ppm.

The chlorinous smell around heavily used pools is chloramine not free chlorine. It is chlorine combined with ammonia. The combined chlorine level can be smelled at only 0.2 ppm. They are also body and skin irritants at that level. You remove them by superchlorination with 10 times the amount of combined chlorine or by using a non-chlorine shock.