It is a noble gas and a natural component of air. Like all noble gases, it does not react: it cannot burn and is not toxic.
Nevertheless, care should be taken to ensure adequate ventilation in small rooms. You can also find out more about this topic from your gas dealer.
(Gas consumption is extremely low: a flow rate of 2 - 3 liters/minute is optimal. This corresponds to a pressure of only approx. 0.4 bar).