Detailed answer

When you experience a change in altitude, the air pressure decreases and the humidity levels may also vary. These factors can contribute to the temporary swelling and expansion of the skin's pores, causing them to appear larger. Additionally, when the skin becomes dehydrated due to dry air at higher altitudes, it can lead to decreased skin elasticity, making the pores appear more prominent. However, once you return to your usual environment, your skin should gradually regulate itself and the appearance of your pores should return to normal. It's important to maintain proper skincare routine, including gentle cleansing and moisturizing, regardless of the altitude, to keep your skin healthy.