What happens to the ascent from 40 fsw to 30 fsw during surD?

The ascent from 40 feet of seawater (fsw) to 30 fsw during a submerged decompression (surD) should indeed take place during an air break. An air break is strategically used in diving practices to allow for a safer ascent, and it typically involves pauses at specific depths where divers can breathe surface air, which helps to reduce nitrogen absorption in tissues and manages the risk of decompression sickness.

In this context, transitioning from 40 fsw to 30 fsw indicates a controlled ascent phase, which is fundamental in managing the diver’s physiological responses to pressure changes. During this air break, divers can allow their bodies to off-gas, facilitating the proper release of inert gases accumulated while under pressure. This careful approach ensures safety for divers, particularly during the critical phase of ascent where rapid changes in pressure can pose increased risks of decompression illness.

While other options might address different scenarios or suggest alternative methods, they do not align with the recommended procedure of using an air break for safety during such an ascent.