Is there any laws on how long a inmate should be let out into th yard for sunshine and fresh air?

i was Incarcerated a year ago in Lyon County Nevada. I was there for two weeks and not once were we let outside. We were able to come out of our cells, but never actually out side. I met two women in there that were there for one year and they said that they had only been outside 2-3 times and that was only if they had to do some kind of work for the jail. Is there any kind of laws on this?