Impact of acute temperature and air pollution exposures on adult lung function: A panel study of asthmatics
This study investigates the effects of acute exposure to fine particulate matter (PM2.5) and dry bulb globe temperature (DBGT) on lung function in adults with asthma. It finds that short-term increases in PM2.5 are linked to increased use of rescue bronchodilators, while DBGT is associated with improved lung function, specifically measured as forced expiratory volume (FEV1). Further research is suggested to explore the underlying mechanisms of these associations.
College of Health researcher(s)
College unit(s)
Abstract
Background
Individuals with respiratory conditions, such as asthma, are particularly susceptible to adverse health effects associated with higher levels of ambient air pollution and temperature. This study evaluates whether hourly levels of fine particulate matter (PM2.5) and dry bulb globe temperature (DBGT) are associated with the lung function of adult participants with asthma.
Methods and findings
Global positioning system (GPS) location, respiratory function (measured as forced expiratory volume at 1 second (FEV1)), and self-reports of asthma medication usage and symptoms were collected as part of the Exposure, Location, and Lung Function (ELF) study. Hourly ambient PM2.5 and DBGT exposures were estimated by integrating air quality and temperature public records with time-activity patterns using GPS coordinates for each participant (n = 35). The relationships between acute PM2.5, DBGT, rescue bronchodilator use, and lung function collected in one week periods and over two seasons (summer/winter) were analyzed by multivariate regression, using different exposure time frames.
In separate models, increasing levels in PM2.5, but not DBGT, were associated with rescue bronchodilator use. Conversely DBGT, but not PM2.5, had a significant association with FEV1. When DBGT and PM2.5 exposures were placed in the same model, the strongest association between cumulative PM2.5 exposures and the use of rescue bronchodilator was identified at the 0–24 hours (OR = 1.030; 95% CI = 1.012–1.049; p-value = 0.001) and 0–48 hours (OR = 1.030; 95% CI = 1.013–1.057; p-value = 0.001) prior to lung function measure. Conversely, DBGT exposure at 0 hours (β = 3.257; SE = 0.879; p-value>0.001) and 0–6 hours (β = 2.885; SE = 0.903; p-value = 0.001) hours before a reading were associated with FEV1. No significant interactions between DBGT and PM2.5 were observed for rescue bronchodilator use or FEV1.
Conclusions
Short-term increases in PM2.5 were associated with increased rescue bronchodilator use, while DBGT was associated with higher lung function (i.e. FEV1). Further studies are needed to continue to elucidate the mechanisms of acute exposure to PM2.5 and DBGT on lung function in asthmatics.
FAQ: Impact of Temperature and Air Pollution on Adult Lung Function
What was the purpose of this study?
This study aimed to investigate the relationship between short-term exposure to fine particulate matter (PM2.5), dry bulb globe temperature (DBGT), and lung function in adults with asthma. The researchers wanted to understand how changes in air quality and temperature might affect the respiratory health of individuals with this condition.
How was the study conducted?
The study involved 35 physician-diagnosed asthmatics who participated in the Exposure, Location, and Lung Function (ELF) study. Participants used a mobile spirometer to measure their lung function (specifically, forced expiratory volume at 1 second, or FEV1) twice a day for one week periods during summer and winter seasons. They also carried a GPS-enabled phone to track their location and reported their asthma medication usage and symptom experience via a mobile app.
Hourly PM2.5 and DBGT exposures were estimated for each participant by combining air quality and temperature data from monitoring stations with their time-activity patterns based on GPS coordinates.
What were the key findings regarding PM2.5?
The study found that increases in PM2.5 levels were associated with a higher likelihood of participants using rescue bronchodilator medication. The strongest association was observed for cumulative PM2.5 exposure over the 24 and 48 hours preceding the lung function measurement. Notably, this relationship was independent of temperature and more pronounced during summer.
What were the key findings regarding DBGT?
Contrary to PM2.5, DBGT was positively associated with FEV1. This means that higher temperatures were linked to better lung function in participants. These associations were statistically significant for DBGT measured at the time of the FEV1 reading and for cumulative exposures over the preceding 6 hours.
Did the study find any interaction between PM2.5 and DBGT?
No significant interactions between PM2.5 and DBGT were observed for either rescue bronchodilator use or FEV1. This suggests that the effects of these two environmental factors on lung function in asthmatics are independent of each other.
Were there any unexpected findings?
While the study found that PM2.5 increased the use of rescue bronchodilators, it also observed a positive association between PM2.5 and FEV1 when the two variables were analyzed independently. This unexpected finding is likely due to the exclusion of FEV1 readings taken within 6 hours of rescue bronchodilator use, which removed some of the higher PM2.5 exposures from the analysis.
What are the limitations of the study?
The study has several limitations, including a small sample size consisting mostly of white females, which limits the generalizability of the results. Additionally, the exposure assessment relied on ambient monitoring data, which may not perfectly represent personal exposures, particularly for time spent indoors.
What are the implications of the study?
This study highlights the importance of considering both air pollution and temperature when evaluating the respiratory health of individuals with asthma. The findings suggest that public health interventions aimed at reducing PM2.5 exposure, especially during summer, could be beneficial for managing asthma in vulnerable populations. Further research is needed to confirm these findings and explore the long-term health effects of these environmental exposures.