## 6 Challenges and Opportunities
### Technical Scalability and Reliability  
Building a robust and expansive IoPVT infrastructure for outdoor safety monitoring requires addressing multiple interrelated challenges related to scalability and reliability. As the number of sensors, connected devices, and participating stakeholders deployed grows, so does the complexity of ensuring consistent data collection and analysis across diverse environments: urban high rises, rural farmlands, and coastal ecosystems each present distinct conditions that strain network connectivity and sensor performance. In addition, the sheer volume of data generated by real-time monitoring can quickly overwhelm centralized processing infrastructures, calling for distributed computing strategies at the edge and fog layers to handle localized analytics and reduce bottlenecks.  
On the hardware side, sensors must be engineered to withstand harsh environmental conditions, including extreme temperatures, high humidity, and corrosive elements such as salt in coastal regions [107]. Cities like Montreal, for example, have harsh winters that require devices that can still operate through ice, snow, and subzero temperatures. Coastal areas exposed to salty air, storms, and fluctuating tide heights present a different kind of durability challenge, but one that is equally demanding. This mitigates any deterioration, as materials and enclosures must perform just as well and stand up to the time and test associated with weatherproofing. Another key consideration is power efficiency [108]. Remote or autonomous sensor deployments often use batteries or energy harvesting solutions to maintain continuous operation, which depends on factors such as temperature or the seasonal availability of sunlight. The strategic placement of sensors, optimizing access to maintenance while enabling successful repairs/migration, further complicates the large-scale deployment of IoPVT systems.  
On the software side, scalability lies in the capacity to process enormous data streams without sacrificing responsiveness or security [109]. The heterogeneous sensor feeds must be ingested, stored, and indexed efficiently in data management systems to allow for near-real-time analysis and the retrieval of relevant information. Also critical is fault tolerance, where a single point failure at the network layer or within the cloud infrastructure can create surveillance gaps, slow notifications, or even complete system outages. Instead, to distribute computational loads and decrease latency (critical for fog networks in remote regions or in bandwidth-limited scenarios), developers can consider introducing redundant network architectures, adding load-balancing mechanisms, or utilizing edge/fog analytics. In addition, end-to-end encryption, other security measures, and secure communication protocols are needed to secure sensitive information, from health data to location data. The third is to install a wide range of sensors, third-party APIs, and different IoPVT layers that require open standards and adaptable middleware solutions to promote interoperability. This level of interoperability is crucial for future-proofing the system so that new technologies can be integrated into it and enable incremental upgrades over time.  
Ultimately, ensuring technical scalability and reliability is more about strategic planning and design than technological upgrades. To do so, they must consider topics such as optimal sensor position, appropriate communication protocols for local conditions, or a flexible architecture that can be easily changed. With these aspects in mind, it can be ensured that IoPVT-enabled outdoor safety monitoring can meet the needs of more users and more environments without the degradation of data quality and system responsiveness.