Remaining within the recommended limiting ppO2 of 1.4 bar helps nitrox divers to avoid?

Remaining within the recommended limiting partial pressure of oxygen (ppO2) of 1.4 bar is crucial for nitrox divers to avoid oxygen toxicity. Oxygen toxicity can occur when divers are exposed to elevated pressures of oxygen over extended periods, leading to various potential symptoms ranging from visual and auditory disturbances to seizures and other severe neurological impacts. By adhering to the ppO2 limit of 1.4 bar, divers minimize the risk of experiencing these detrimental effects while allowing for extended dive times and greater depths relative to standard air diving.

The other options pertain to different physiological effects but do not relate directly to the exposure limits of oxygen in the same way. Helium narcosis and nitrogen narcosis are related to the effects of gases other than oxygen at depth and do not apply in the context of managing oxygen exposure. Decompression illness is associated with the improper ascent and gas bubbles forming from dissolved gases, rather than oxygen toxicity itself. Therefore, focusing on maintaining a ppO2 of 1.4 bar directly supports divers' health by preventing the onset of oxygen toxicity.