There must be an evacuating air duct (as in a fume hood) with a wide "funnel" above the instrument, continually removing ambient air. With ICP you normally work with very low concentrations, especially if your detector is MS, so typically nothing more special is necessary viz. air contamination with heavy metals.

The control of laboratory ventilation by using a differential pressure system may be of help.

https://www.ncbi.nlm.nih.gov/books/NBK55867/

Some detection limits are determined by the level of airborne particulates. If you are in a cleanroom where the air supply is filtered, DLs will be lower. This is inconvenient though, hard to run instrumentation in a "bunny suit". Passing the make-up air through a HEPA filter is a compromise.

Thanks a lot for your answers!