What do you mean by 'hypoallergenic'?

The word hypoallergenic is responsibly used in situations where a serious effort has been made to minimize the chance of allergic reaction. The high-tech Aera device creates a hypoallergenic scent effect with a ratio less than 10ppm (parts per million) between fragrance molecules and air molecules. This is well below the airborne concentration threshold that might trigger a physiological allergic response.