During the early spring of 1941, Pauling began to feel ill. His energy waned and his extremities became noticeably swollen with unprocessed fluids. In March he was diagnosed with a form of Bright's disease, an illness which destroys the kidneys, most often resulting in death. Pauling was soon put under the care of Dr. Thomas Addis, a leading renal specialist. After two weeks of testing, Addis prescribed a low protein diet, an unorthodox treatment which was later credited with reversing the damage done to Pauling's kidneys and ultimately saving his life. Despite Addis' care, Pauling was bedridden for weeks and, even after his recovery began, remained unable to work for extended periods of time.

Despite his absence from the lab, Pauling's researchers forged ahead, corresponding frequently with Pauling and visiting when they could. Fortunately for Pauling, the NDRC recognized the significance of the meter and agreed to extend the contract despite the responsible investigator's nonattendance.

While Pauling lay ill, J. Holmes Sturdivant assumed a larger role in the oxygen meter program. Sturdivant had worked with Pauling since 1927, serving as a lab assistant and then becoming a member of the Caltech chemistry staff. He quickly became a trusted overseer of the project, both tending to the daily needs of the laboratory and contributing to the research done therein. A year later, when recommending Sturdivant as a candidate for a position on another war project, Pauling wrote that "I rate him as the most reliable and trustworthy man that I know."

By June Pauling was making frequent visits to the lab. As his health improved, his correspondence with the NDRC administrators became increasingly positive. The meter was a success. The NDRC, pleased with Pauling's work, renewed his contract, requesting that five additional meters be manufactured and distributed according to Committee orders. Despite the production demands placed on his team, Pauling insisted that work be done to improve the design. Wood, charged with finding creative ways to improve the meter's durability and accuracy, devloped a prototype using two magnets rather than one that ultimately led to a sturdier, more accurate model.