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Digital Asthma Control at Scale: The AIR Louisville Case Study

Executive Summary

AI-powered digital therapeutics and smart inhalers were at the heart of one of the first large-scale public–private initiatives aimed at asthma control. AIR Louisville used Bluetooth inhaler sensors from Propeller Health to reduce the use of rescue inhalers by 78% and increase symptom-free days by nearly 50% over a 12-month period. By integrating patient-reported inhaler use with environmental air quality data and clinical records, the project became a model for future smart city health programs.

To learn more about how digital infrastructure supports such programs, see our overview of How Technology Is Changing Pharma: A Complete Guide.

Background: Asthma and Environmental Triggers in Louisville

Asthma remains one of the most common causes of emergency room visits in the United States. Despite effective treatments, patients often fail to anticipate or respond to environmental triggers such as pollen, ozone, or nitrogen dioxide (NO₂).

Louisville, Kentucky, ranks above average in both allergen load and air pollution exposure, creating an ideal environment to pilot an environmental- and tech-integrated asthma program. In partnership with Propeller Health, the city launched AIR Louisville, a program that combined real-time digital therapeutics (inhaler data) with environmental sensor networks and EHR integration to track and reduce asthma symptoms across the population.

The Solution: Smart Devices and Seamless Integration

At the center of AIR Louisville’s success was a Bluetooth inhaler sensor from Propeller, attached to each participant’s rescue inhaler (SABA). Each time the inhaler was used, the device recorded the actuation, timestamp, and GPS coordinates. These were transmitted to the patient’s smartphone and then sent to the Propeller Cloud platform.

Cloud-based analytics matched usage data with real-time Air Quality Index (AQI) feeds from city monitoring stations. If air quality exceeded the user’s personalized threshold, the system would send:

  • A push alert to the patient, encouraging preventive measures
  • A FHIR-compliant notification to the patient’s physician within the Epic EHR system

To extend this ecosystem beyond mobile users, city agencies also tested LoRaWAN-connected air quality sensors (such as Tektelic eDoctor) in public schools. While the test phase showed promise, the sensor network was not scaled beyond the proof-of-concept stage as of 2025.

For more on connected inhaler innovation and growth, see Smart Inhalers by 2030: Market and Key Players.

Results and Key Outcomes

Over a 12-month period, AIR Louisville demonstrated compelling improvements in asthma management:

  • Rescue inhaler use declined by 78%
  • Symptom-free days increased by 48%

These outcomes suggest not only better control over chronic symptoms, but also higher treatment adherence and improved patient quality of life. Importantly, the Bluetooth inhaler device served as more than a tracker-it became a behavioral nudge, encouraging patients to identify and avoid environmental triggers before symptoms escalated.

Unlike traditional interventions, the program empowered both patients and providers with actionable, context-aware insights. The real-time data loop fostered greater patient self-awareness and informed clinical decision-making.

Expansion Plans: Then and Now

At the time of its initial success, AIR Louisville’s leaders announced plans to scale the program statewide: connecting 15,000 patients across Kentucky, deploying air sensors to 30 schools, and building an AI-powered predictive module for exacerbation forecasting.

However, these expansion goals were not realized. In February 2025, ResMed discontinued all commercial operations under the Propeller Health brand, and no formal continuation of the program has been announced by Kentucky DPH. The initiative remains widely studied as a successful pilot, but it is not currently active in Louisville or statewide.

Funding and Reimbursement Update

Initially, remote monitoring was funded under CPT 99454, but this has since been superseded by codes better aligned to connected devices.

As of January 2023, smart inhalers that transmit therapeutic use data are more appropriately billed under Remote Therapeutic Monitoring (RTM) code 98978. This CPT code covers transmission of respiratory system data on at least 16 days per 30-day cycle, along with physician interpretation and feedback.

This change reflects CMS’s evolving approach to digital health reimbursement, particularly for respiratory conditions like asthma and COPD.

Call to Action: Ready to Build Your Own Smart Asthma Program?

The AIR Louisville pilot proves that digital asthma control is not just feasible-it’s effective. For cities, clinics, or payers exploring smart respiratory care, now is the time to evaluate scalable solutions.

  • Join our webinar: “From Smart Inhaler to Smart City”June 26, 2025
  • Download our white paper: Includes a practical implementation checklist, digital workflow templates, and ROI models for smart asthma programs.

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