Understanding and Treating the Health Effects of Wildfire Smoke

Understanding and Treating the Health Effects of Wildfire Smoke

By Aloke Chakravarti MD, FCCP, and Zein Kattih, MD
Chest Infections and Disaster Response Network
August 10, 2023

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In recent years, the global incidence of unplanned, uncontrolled wildfires has increased. Rising temperatures, decreased precipitation, and alterations in wind patterns have resulted in changes in the distribution of wildfire smoke to areas that have not experienced this previously. Clinicians in these areas have been charged with meeting the demand for medical attention and management for new symptoms and exacerbation of preexisting pulmonary disease, as well as educating their patients about the impact of wildfire smoke.

Particulate matter (PM) of various sizes is ubiquitous. PM_2.5, which is 2.5 microns or smaller, has been increasing from wildfire smoke, in addition to other sources. PM_2.5, byproducts of combustion, and vapors are all rapidly and systemically absorbed through the lungs. With acute exposure to these irritants, both patients and the worried well will seek medical attention.

People tend to seek medical attention about 3 days after the onset of harmful levels of smoke. This is likely due to a combination of cumulative exposure as well as attempts at relieving symptoms with inhalers that have already been prescribed. The incidence of all-cause respiratory symptoms is notably increased. Patients tend to present with respiratory symptoms of cough, chest discomfort, and sinonasal and eye irritation. Long-term sequelae appear to be in the form of increased cardiovascular morbidity and mortality.

Data on the impact of wildfire smoke and pulmonary disease show a clear increase in asthma health care utilization (ER visits, admissions, steroids, nebulizers, and short-acting beta agonists). However, the degree to which that increase represents an increase in exacerbations or in new diagnoses is unclear.

While data looking retrospectively at ICD-9 codes for individual ER visits for asthma or administration of a short-acting beta-agonist indicates a doubling in the number of such visits, separate registries of patients meeting American Thoracic Society criteria for severe asthma shows a more modest increase in health care utilization. The literature suggesting an increased risk of a new diagnosis of asthma is assumed from an increased incidence of outpatient consultations for asthma.

Particularly in light of the recommendations made in the 2022 GINA Report, it is imperative to demonstrate the presence of airway obstruction and bronchodilator reversibility on spirometry to confirm the diagnosis in these patients once the acute symptoms resolve. Patients with a confirmed diagnosis of asthma appear to tolerate wildfire smoke reasonably well, likely because they have inhaled corticosteroids and an asthma action plan in place.

Messaging should focus on judicious use of emergency resources for those near the wildfire itself. Emergency departments should focus their attention on those with a risk of thermal injury to the face and airway, carbonaceous sputum, carbon monoxide toxicity, and exacerbations of preexisting asthma. Focusing management of symptoms involving the eyes, nose, and throat results in symptomatic relief, while reserving strained or scarce asthma health care resources for patients with confirmed obstructive airways disease. Prevention of symptoms with medium- to high-speed household air purifiers with HEPA filters within closed windows may provide benefit. It is recommended that people use N95 or KN95 masks, and shelter indoors.

Wildfire smoke and resultant poor air quality is associated with an increase in inpatient and outpatient health care utilization and can strain limited resources. A significant portion of people seeking medical attention are those that have no underlying diagnosis of a pulmonary disease and are not experienced in how to manage new respiratory symptoms from smoke hypersensitivity (ICD-10 J70.5). Clinicians should focus on acute symptom management in those patients and defer a diagnosis of obstructive airways disease until it can be objectively evaluated. Patients with preexisting asthma clearly benefit from an asthma action plan and have been shown to have favorable outcomes in the setting of wildfire smoke exposure.

References

Hadley MB, Henderson SB, Brauer M, Vedanthan R. Protecting cardiovascular health from wildfire smoke. Circulation. 2022;146(10):788-801. doi: 10.1161/CIRCULATIONAHA.121.058058. Epub 2022 Sep 6. PMID: 36067276.

Skinner R, Luther M, Hertelendy AJ, et al. A literature review on the impact of wildfires on emergency departments: enhancing disaster preparedness. Prehosp Disaster Med. 2022;37(5):657-664. doi: 10.1017/S1049023X22001054. Epub 2022 Jul 25. PMID: 35875982; PMCID: PMC9470518.

Gan RW, Liu J, Ford B, et al. The association between wildfire smoke exposure and asthma-specific medical care utilization in Oregon during the 2013 wildfire season. J Expo Sci Environ Epidemiol. 2020;30(4):618-628. doi: 10.1038/s41370-020-0210-x. Epub 2020 Feb 12. PMID: 32051501; PMCID: PMC8745685.

Beyene T, Harvey ES, Van Buskirk J, et al. “Breathing fire”: impact of prolonged bushfire smoke exposure in people with severe asthma. Int J Environ Res Public Health. 2022;19(12):7419. doi: 10.3390/ijerph19127419. PMID: 35742668; PMCID: PMC9224478.

Noah TL, Worden CP, Rebuli ME, Jaspers I. The effects of wildfire smoke on asthma and allergy. Curr Allergy Asthma Rep. 2023:23(7):375-387. doi: 10.1007/s11882-023-01090-1. Epub 2023 May 12. PMID: 37171670; PMCID: PMC10176314.

Gao Y, Huang W, Yu P, et al. Long-term impacts of non-occupational wildfire exposure on human health: a systematic review. Environ Pollut. 2023;320:121041. doi: 10.1016/j.envpol.2023.121041. Epub 2023 Jan 10. PMID: 36639044.

Rice MB, Henderson SB, Lambert AA, et al. Respiratory impacts of wildland fire smoke: future challenges and policy opportunities. an official American Thoracic Society Workshop report. Ann Am Thorac Soc. 2021;18(6):921-930. doi: 10.1513/AnnalsATS.202102-148ST.