Rationale for developing tunable laser spectroscopy (TLS) technology for high resolution real-time carbon dioxide monitoring (capnography) in human breath

Evolution and Applications of Recent Sensing Technology for Occupational Risk Assessment: A Rapid Review of the Literature

Over the last decade, technological advancements have been made available and applied in a wide range of applications in several work fields, ranging from personal to industrial enforcements. One of the emerging issues concerns occupational safety and health in the Fourth Industrial Revolution and, in more detail, it deals with how industrial hygienists could improve the risk-assessment process. A possible way to achieve these aims is the adoption of new exposure-monitoring tools. In this study, a systematic review of the up-to-date scientific literature has been performed to identify and discuss the most-used sensors that could be useful for occupational risk assessment, with the intent of highlighting their pros and cons. A total of 40 papers have been included in this manuscript. The results show that sensors able to investigate airborne pollutants (i.e., gaseous pollutants and particulate matter), environmental conditions, physical agents, and workers' postures could be usefully adopted in the risk-assessment process, since they could report significant data without significantly interfering with the job activities of the investigated subjects. To date, there are only few "next-generation" monitors and sensors (NGMSs) that could be effectively used on the workplace to preserve human health. Due to this fact, the development and the validation of new NGMSs will be crucial in the upcoming years, to adopt these technologies in occupational-risk assessment.

Tunable laser spectroscopy for carbon dioxide capnography and water vapor sensing inside a breathing mask: application to pilot life support

Tunable laser spectroscopy (TLS) near 2683 nm was used to measure carbon dioxide and water vapor inside a pilot mask during jet fighter flights. Measurement frequency was 100 Hz in order to capture breathing profiles and other gas flow dynamics. Analysis of the full inhalation and exhalation breathing cycle allowed precise monitoring of breathing performance and interaction of the pilot with the life-support system. Measurements revealed dynamic phenomena pertaining to mechanical gas flow and pilot respiration that may be used to understand gas delivery stresses imposed upon the pilot and pilot physiology during flight. Typically, such measurements are made with non-dispersive infrared (NDIR) instrumentation for only carbon dioxide with intrinsic challenges regarding time and optical resolution. The TLS approach is a major advance because the sensor is placed directly into the mask improving its time response and enabling use of water vapor measurements that are less impacted from memory effects. This article presents the implementation of TLS and shows highly time-resolved pilot breathing data for high-performance aircraft tests.

The physics of human breathing: flow, timing, volume, and pressure parameters for normal, on-demand, and ventilator respiration

Normal breathing for healthy humans is taken for granted; it occurs without conscious effort using ambient (1-atmosphere) pressure with 21% oxygen (O2) concentration. The body automatically adjusts for stress, exercise, altitude, and mild disease by increasing the volume and frequency of breathing. Longer term adaptations for exercise and altitude include increases in red blood cell counts and higher concentrations of capillaries in muscle tissue. When more challenging external environmental conditions or pulmonary illnesses exceed the capability for these adaptations, the human system requires technology to maintain sufficient ventilation to preserve life. On the environmental side there are two conditions to be addressed: toxicity of the surrounding atmosphere and changes in external pressure and O2concentration. On the medical side, mechanisms for assisting breathing include O2supplementation at ambient pressure, positive pressure/flow without additional O2, or a combination of both. This overview describes the various technologies applied to maintaining a safe breathing environment. Topics for environmental intervention include filter-based and flowing air-supply masks for toxic environments (occupational and laboratory protection), and on-demand gas supply systems for firefighters, self-contained underwater breathing apparatus divers, and altitude (high performance aircraft, spacecraft) applications. The topics for medical intervention include nasal cannula, continuous positive airway pressure, and medical ventilators. The primary purpose of this article is to provide a basic understanding of normal human breathing and the adaptation of breathing in different environments using available technologies.