When searching for a tanning unit (at home or professional use) it is important to find one that has a good balance of UVA and UVB – those are the low pressure units. High pressure units have much greater amounts of UVA and only small amounts of UVB. While UVA is what causes the skin to bronze, it can also be harmful if the dose is too high. Using a light that has high amounts of UVA does not mean that it will automatically cause damage to your skin/body, it is with continued use over long periods of time that it becomes dangerous. Tanning units need to have more UVA than UVB in order to actually cause the skin to tan, but those levels need to be closely monitored in order to not cause damage.
Low Pressure Units have a good balance of UVA and UVB: 75% UVA and 25% UVB.
High Pressure Units have much higher amounts of UVA: 95% UVA and 5% UVB.
In order to keep your body healthy while tanning, make sure stick with low pressure tanning units.