The pharmaceutical industry refers to companies that research, manufacture, or sell small-molecule (chemical-based) or large-molecule (biological-based) drugs. Maintaining hygienic conditions is a critical part of pharmaceutical research and production. Vaporized hydrogen peroxide (H2O2) is often used as a decontaminating agent for materials that cannot withstand high temperatures—such as laboratory or manufacturing equipment, pill bottles, and syringes. However, if residual (post aeration) H2O2 levels remain too high, they can adversely affect drug stability, efficacy, and safety. Therefore, residual H2O2 levels must be periodically or continuously monitored at ppb levels to ensure drug stability, efficacy, and safety.