Why does the cherry blossom color-changing mask change color?

Cherry blossom color-changing mask is coated with temperature-changing toner. According to relevant data, the color-changing mask can change color with the change of temperature by using temperature-changing powder. When people wear this color-changing mask, the mask will not change color under normal breathing. When a person's body temperature is higher than normal, the exhaled gas temperature will be higher than normal. Therefore, the mask will immediately change color and achieve the warning effect.