Louisville, Kentucky has some of the worst air pollution in the U.S., which is particularly bad news for the 85,000 people in surrounding Jefferson County (about 11 percent of the population [PDF]) who have been diagnosed with asthma.

The air quality situation in Louisville won’t be changing anytime soon, but a new study with sensor-equipped inhalers shows that technology can help people with asthma cope, as CityLab reports. The two-year AIR Louisville project involved the Louisville government, the Institute for Healthy Air Water and Soil, and a respiratory health startup called Propeller, which makes sensors for inhalers that can track location and measure air pollutants, humidity levels, and temperature.

Propeller's inhaler-mounted sensors allowed the researchers to monitor the relationship between asthma attacks and environmental factors and provided new insight on how air quality can change from neighborhood to neighborhood. The sensors—which are already used by doctors, but have never been deployed citywide before—can measure levels of nitrogen oxide, sulfur, ozone, particulate matter, and pollen in the air, plus track location, temperature, and humidity, all of which can impact the risk of asthma attacks. The sensors send Propeller data on when, where, and how many "puffs" patients take to track how often people are resorting to emergency medication.

Propeller sent out app notifications to warn the Louisville program participants of greater risk of an asthma attack on bad air quality days, and showed them where and when the most asthma attacks happened around the city.

Propeller

The Propeller program illuminated just how much more asthma-triggering pollution the city’s west side (predominantly home to poor, African-American residents) faces compared to other neighborhoods. The data also showed that ozone provoked an uptick in asthma attacks throughout the city, namely along highways. The study may end up influencing air quality regulations, since the researchers found that air pollutants became problematic for asthma sufferers even under the legal levels.

The program had huge short-term benefits, too, beyond collecting research for city policies. By the time it ended in late June, the study clearly had a significant impact on the nearly 1200 people with asthma and chronic obstructive pulmonary disease (COPD) who took part. The asthma group showed a decline in average inhaler use after a year. There was an 82 percent decline in people's weekly average uses of rescue inhalers at the 12-month follow-up, and the participants had twice the number of symptom-free days. The majority of participants said they understand their asthma "very well" or "well," can better control it, and feel confident about avoiding a bad asthma attack.

Now that the program is over, the institutions involved are still working to launch new policies based on the results, like creating citywide asthma alerts and planting more trees.

[h/t CityLab]