Smoke contamination associated with increased hospitalizations among elderly people

Currently, over 30% of the US experience Drought conditions,¹ The threat of wildfires remains high as the country quickly approaches wildfire season. May to November Nationwide.² However, the actual fire threat is not the only harmful thing to people in the surrounding area. According to a new study published in Jama Network Open,³ Smoke contamination has affected seniors in the western US, leading to increased hospitalizations Respiratory diseases.

The West of the United States is expected to increase wildfires and wildfire exposures due to climate change, but research covering the effects of that exposure is limited. Most studies focus on smoke exposure mortality, respiratory and cardiovascular outcomes, along with the potential association between maternal and child health, diabetes and diarrhea. The purpose of this study is to take a broad approach to the link between wildfires and health outcomes. Jama Network Open The study assessed the relationship between 13 causes of hospitalizations in elderly people and wildfire smoke exposure between 2006 and 2016 in Western states in the US.

The 11 states included in this study were Arizona, Colorado, Nevada, Utah, New Mexico, California, Montana, Oregon, Idaho, Wyoming and Washington. Data included all hospitalizations between 2006 and 2016 from May 1 to October 31. This is the main time of wildfires. Researchers used claims data for Medicare inpatients, primarily for their studies. This included data from adults over the age of 65. This was enrolled in the Service Fee Program for at least one month during the study period.

Hospitalizations related to respiratory disease increased due to smoke exposure | Image credit: Aleksandr lesik -stock.adobe.com

Diagnostic codes were used to identify 13 causes of hospitalization. They included cancer, injuries, respiratory diseases, infectious and parasitic diseases, and cardiovascular diseases. Secondary analysis also evaluated the association with smoke particulate matter 2.5 (PM_2.5) and subcoat categories. Daily PM_2.5 Concentrations were taken from Childs et al. Smoke Day was defined as the day overhead smoke plume crossed the county.

The average number of smoke days (SD) was 498 (160) in all Western provinces. A total of 10,369,361 participants were included in the study, of which 46.9% were male and 80.7% were Caucasian. Among the cohort was 1,333,143 unique individuals with a total of 4,760,651 unscheduled hospitalizations.

The reason for unplanned hospitalization was most often cardiovascular disease, with an average daily rate of 7.92 (6.90) per 100,000 people. Gastrointestinal diseases, average daily rate of 3.62 (4.39) per 100,000. Respiratory disease, average per 100,000 per day (4.39).

The researchers found that respiratory disease and cardiovascular hospitalization remained flat at low levels of exposure and began to increase at 25 μg/m.³;This was a plateau at 40μg/m³. Daily hospitalizations for respiratory disease increased 2.40 (95% CI, 0.17-4.63) per 100,000 people when smoke concentrations increased from 0 to 40 μg/m each week.³. Cardiovascular hospitalization increased 2.61 (95% CI, –0.09 to 5.30) per 100,000 when concentrations increased from 0 to 40 μg/m³.

The only causes of hospitalizations that were significantly associated with smoke were respiratory diseases, particularly pneumonia (36.9% of all respiratory diseases), chronic obstructive pulmonary disease (20.4%), and respiratory failure (15.5%).

This study had several limitations. Exposure measurement errors may be present in the study. Smoke concentrations are difficult to estimate. County-level exposure measurements are not a complete representation of exposure. Time series analysis allows for residual confounding. The wildfires have been more intense since 2016, but have not been explained for the next few years. Higher concentrations of smoke could not be assessed.

An increase in hospitalizations related to respiratory diseases was found in elderly people in the western United States. “This information can be used by both policymakers and clinicians to design policies and guidelines to protect vulnerable elderly people from the health threats posed by wildfire smoke,” the authors concluded.

reference

1. Current State Conditions: April 16, 2025 – April 22, 2025. National Integrated Drought Information System. Updated April 25th, 2025. Accessed April 29, 2025. https://www.drought.gov/current-conditions
2. When is the US wildfire season? Western Fire Chiefs' Association. October 8th, 2024. Accessed April 29, 2025. https://wfca.com/wildfire-articles/when-is-wildfire-season/
3. Vega SL, Childs ML, Aggarwal S, Nethery RC. Exposure of wildfire smoke in elderly people and hospitalization specific to the cause. Jama Netw Open. 2025; 8(4): E257956. doi:10.1001/jamanetworkopen.2025.7956