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Boston Scientiffc Report: ABN-1487A 7/28/2024 Page 2 SUMMARY Boston Scientiffc commissioned follow-up sound monitoring at its Arden Hills manufacturing site, speciffcally Building #14, in response to prior nighttime assessments conducted near the northwest corner of the same building. On July 17–18, 2025, Sound Inspectors deployed a sound analyzer to continuously monitor noise levels at the same approximate location used in previous studies—approximately 11 feet high in a tree along the walking path. This site was previously determined to be the closest secure point between the mechanical room of Building #14 and the nearest residence on Wynridge Drive. During the monitoring period, sound levels at the designated measurement location ranged from an LAeq of 49.5 dBA to 68.0 dBA. Elevated readings were primarily attributed to transient sources, including freeway and local tralfic, horns, lawn mowers, sprinkler systems, and pedestrian activity along the nearby path. The lowest levels were consistently observed during nighttime hours when external human -generated noise was minimal. According to Boston Scientiffc, the rooftop mechanical equipment on Building #14 operates continuously. Therefore, the lowest recorded sound levels during quiet nighttime intervals are reasonably assumed to reifect the dominant noise contributions from the building itself. To better isolate building-generated sound from background transients, data was collected at one-minute intervals. These high-resolution measurements enabled calculation of LA10 and LA50 values per interval, which were then aggregated to hourly metrics using the arithmetic mean. Table 1 -Hourly Nighttime Ln Average 2025-July 17 2025-July 18 Time L10 L50 L10 L50 12 AM 50.2 49.7 52.4 51.7 1 AM 50.2 49.8 52.0 51.5 2 AM 50.2 49.8 53.9 53.1 3 AM 50.2 49.8 54.9 53.8 4 AM 50.5 50.1 54.3 53.4 5 AM 51.5 51.1 54.6 53.9 6 AM 54.0 52.8 54.8 54.1 10 PM 52.6 51.9 11 PM 52.2 51.6 As shown in Table 1, LA50 values during four hourly nighttime intervals on July 17 fell below the Minnesota Pollution Control Agency (MPCA) Noise Area Classiffcation 1 threshold of 50. Additionally, all hourly LA10 measurements remained within the applicable state standard on both monitoring dates. These patterns suggest that transient peak noise events were effectively limited during the measurement period, and the results are reasonably representative of background noise generated by Building #14’s continuously operating equipment.