What is the required availability percentage for Continuous Emissions Monitoring Systems (CEMS) to provide valid data?

The required availability percentage for Continuous Emissions Monitoring Systems (CEMS) to provide valid data is 90%. This standard ensures that the CEMS operate effectively and consistently enough to produce reliable emissions data for regulatory compliance and reporting. A CEMS must be available to operate and gather data most of the time, which helps in accurately assessing and controlling emissions from industrial sources.

Maintaining a 90% availability threshold means that the system must be functional and capable of reporting emissions data for at least 90% of the time during the monitoring period. This level of reliability is crucial for environmental compliance, as it allows regulatory agencies to trust the accuracy of emissions reporting and better manage air quality and pollution levels.

While other availability percentages like 80%, 85%, and 95% may be relevant in different contexts, they do not meet the established requirement for CEMS specifically. Therefore, 90% is the correct answer, aligning with industry standards for ensuring valid emissions monitoring.