On the surface he reports what he saw and tells them that the rifle fire had made sparks, showing that there was elevated oxygen level in the air, as if a different atmosphere was coming through the anomaly.
On the surface, Ryan reports what he saw and tells them that the rifle fire had made sparks, along with his own physical sickness. Stephen concludes that these are signs of an elevated oxygen level in the air, as if a different atmosphere was coming through the anomaly.