# Understanding Oxygen Concentrator Failures in Low Resource Settings: The Role of Dust and Humidity
OCs are designed to provide medical-grade oxygen from normal environment air, which is mainly made up of nitrogen (78.08%) and oxygen (20.95%). They do so by filtering out nitrogen from the air and, therefore, concentrating oxygen, relying on pressure swing adsorption (PSA) technology [4] and vacuum pressure adsorption (VPA) [5]. PSA technology is a widely used method for gas separation and purification, which utilizes the adsorptive properties of molecular sieves such as zeolites [6]. After extensive investigation to optimize oxygen concentration devices, it was determined that the most efficient zeolites for this task are the X-type, including NaX, LiX, and LiLSX (with low Si content, Si/Al-1 molar ratio). These zeolites are highly selective for the adsorption of nitrogen and therefore able to generate an air stream rich in oxygen [7]. The adaptability of OCs to different medical needs and environments, from hospitals to remote locations, has proven to be a vital resource during emergencies and pandemics [8]. OCs are cost-effective and lightweight, making them suitable for use in military zones, during disasters, and especially in LRSs, including rural areas [9]. However, at present, the majority of the medical device market is dominated by high-income countries (HICs) such as the USA, many European nations, and Japan. These countries establish and adhere to standard practices and requirements that may not be tailored to or feasible in settings with limited resources [10]. OCs are primarily designed in and for HICs [11]. Consequently, when used in countries with limited infrastructure, their effectiveness and safety may be limited [12]. An illustrative example is portrayed by the various challenges that sub-Saharan African countries face, including a scarcity of funding, medical and biomedical specialized expertise, and a functional health technology management and supply chain, and harsh environmental conditions (e.g., temperature, humidity, and dust), amongst others [13; 14]. In such scenarios, power outages are common events [15] that threaten the safe, efficient, and continuous functioning of medical devices, jeopardizing users' and patients' lives. To partially address such challenges, several studies have focused on designing low-pressure oxygen storage systems [16; 17; 18] and medium-pressure storage systems [19] to supply oxygen for patients during power outages. Although the contamination of zeolites used in oxygen production by PSA is a well-known issue in the adsorption field [20], manufacturers often fail to consider the real environmental challenges mentioned above. OCs and the molecular sieves they contain are quite sensitive to dust and humidity and may not be resilient enough for this kind of environment given their current design. As shown in Figure 1, OCs are currently equipped with an inlet filter to prevent contamination of the zeolites from environmental agents. Despite the fact that the inlet filters could be easily replaced with new ones, they are evidently not tailored to work in harsh environmental conditions [21]. As a consequence, both the molecular sieves and the inlet filter they rely on stop working efficiently after fewer hours of use than expected [22]. Some of the authors of this paper have previously proposed a solution [23] by redesigning the inlet filter of an oxygen concentrator using activated charcoal to prevent the entrance of gross particles into the device, obtaining satisfactory results, but not reaching the performance of the benchmark. Moreover, tropical countries frequently experience ambient conditions of 40 \({}^{\circ}\)C and 95% relative humidity simultaneously, and malfunctions of different OC models operating in such conditions have also been proven [24]. Therefore, dust, temperature, and humidity can be considered as the main factors contributing to the premature failure of oxygen concentrators operating LRSs. However, to the best of our knowledge, it is not well understood which one among them plays the major role in OC failure.