My Black Armour® mat had a strong rubber smell when I unboxed it. Is it safe and non-toxic?

Yes!  Recycled rubber is safe based on many published reports, including dozens of peer-reviewed scientific studies and a comprehensive 2019 study conducted by the US-EPA.  These reports all agree that recycled tire crumb rubber is safe and poses no significant health, air quality or environmental risks. The rubber smell will dissipate with ventilation and time.