An ideal range for humidity whilst in veg state should be around 60 - 65%. That can be very tough to accomplish if you have good circulation with air and are extracting the air from the room.

But I don't believe you can harm these plants with a dryer climate.

The real factor to watch is in flower where you want to keep the humidity at or below 25 - 30%.

And thats easy to do if your ventilation is swift, strong and efficient.

Good luck.