Most pharmacies use heating and cooling systems to maintain proper temperatures. While an individual location might experience an occasional peak in temperature, the analytics team at SmartSense is interested in large-scale trends visible across the country and throughout the year. As we gather large volumes of data with our customers, we are able to examine these patterns and reflect on how well these systems perform, relative to the optimal range for maintaining pharmaceutical products. An excursion occurs when the ambient temperature rises above the desired range (or goes below that range, but this post will focus on warm excursions). If an excursion is too long or too hot, pharmaceuticals can quickly spoil, rendering it ineffective.
For ideal storage of vaccines and other pharmaceuticals, the CDC recommends that room temperatures do not exceed 25°C (77°F), and coolers should be kept between 2°C and 8°C (36°F and 46°F), with a target temperature of 5°C (40°F). The ambient recommendation is made for two reasons: First, this temperature range allows for products stored at room temperature to last as long as possible (some products such as cough syrup can degrade if temperatures go above this ‘room temperature’ threshold). Second, if the environment is too warm, the coolers and freezers have difficulty maintaining desired temperatures.
To better understand the frequency and causes of ambient temperature excursions, we examined data from a sample of 10,000 stores across the United States. Setting the threshold at 77°F (the high end of the CDC recommended range), there were 623,403 total excursions in 2017, which averages to 1,703 excursions per day. We broke that down by duration and peak temperature to see if there were patterns that could provide useful insights into external or internal factors contributing to these mini indoor “heat waves.”
One interesting pattern came to light when we analyzed excursions that lasted over an hour: 70% of pharmacies experienced at least one excursion, and of those excursions, 73% were longer than one hour. On average, 10% of pharmacies experienced an excursion longer than one hour every single day. When plotting the excursions on a calendar plot, we found that the time of the year correlated to the amount of ambient excursions.
Most of the long excursions happened in the summer months. In fact, the number of long excursions in July was almost seven times more than that in January. This increase is most likely a result of the outdoor temperature being significantly warmer and the cooling system not compensating for the heat. In the summer, we saw multiple examples of the ambient environment resting immediately below the upper threshold (77°F in this instance).
When we investigated devices with the highest number of long duration temperature excursions, we found that some of the cooling systems were set too warm or turned off at night. If the central air turned off for the night, the store’s temperature would increase in response to the temperature outside. Typically, central air systems are not turned off at night, but instead switch to a “night time” setting that is lower than the most extreme outside temperatures. We show a typical example below, where the cooling temperature threshold was raised at night, likely to save costs. The typical cooling fluctuations of an active cooling system are present, but they centered at a higher temperature (around 79°F). In the summer, the outdoor temperatures can sit many degrees higher than the pharmacies’ desired temperature. Combined with higher baseline settings, this can result in excursions.
Along with the duration of excursions, we also looked at the maximum temperature of the ambient environment during excursions. These high temperature excursions, also known as hot excursions, were classified as any excursion that exceeded 86°F for any length of time.
Only 4% of pharmacies experienced these hot excursions and they account for less than 2% of all excursions. Nevertheless, they are important to track because of the greater risk they generate for pharmaceuticals.
Unlike long duration temperature excursions, hot excursions typically occur in the winter months. The number of excursions in December is twelve times larger than that in August. This initially seems odd because the winter months are colder, so the effect of the outdoor temps should seem negligible. However, heating systems can produce hot, fast spikes in temperature that are well above the target threshold as they work to maintain a comfortable ambient environment.
When the device that recorded the hottest excursions was examined, we found that the heating system was not operating properly. This caused the pharmacy temperature to swing 20°F in a single day. The temperature history below shows the period leading up to a maintenance event, and how a fix brought temperatures into the desired range.
Monitoring ambient environments throughout the year is important because many different factors can affect the temperature of the pharmacy. The heating and cooling systems act in response to the weather, so when the weather is cold, pharmacies can be warmed through spikes of heat. These heat spikes can sometimes expose the ambient environment to temperatures above the optimal range for pharmaceutical storage, but are often easily addressed when identified. When the weather is warmer, central air will deliver cool air to maintain room temperature. However, ambient environment can be less controlled at night resulting in long duration excursions. Understanding the characteristics and causes of these excursions allows us to set up alerts tailored to each type of issue and rapidly move towards a resolution, helping to ensure medication efficacy.