Trends in chlorine and chloramine gas exposures reported to United States poison centers.

Introduction: Chlorine and chloramine gas inhalation can occur when household cleaners are mixed. The increased emphasis on disinfecting practices during the COVID-19 pandemic may have contributed to an increase in chlorine and chloramine gas exposures in the United States, which has not been studied.

Methods: In a retrospective review, reported data on chlorine and chloramine gas exposures in the National Poison Data System were collected from January 1, 2015, to December 31, 2022. Data included demographics and exposure details, including location, dose, formulation, co-exposures, treatments, and outcomes. Demographic analyses and descriptive statistics were conducted.

Results: During the study period, 85,104 total exposures to chlorine and chloramine gas were reported, consisting of 79,281 isolated exposures and 5,823 co-exposures. Total exposures increased by 61% from 8,385 in 2015 to 13,503 in 2022, with the largest increase of 38.3% occurring from 2019 to 2020. Total exposures remained increased through 2022 with no return to pre-pandemic levels. Most exposures occurred in "own residence" ( = 72,213, 84.9%), with a larger proportion of exposures occurring at home peri-pandemic versus pre-pandemic (88.4% versus 81.7%). One percent ( = 1,030) of exposures were admitted to a non-critical care unit, 0.73% ( = 619) were admitted to a critical care unit, and 0.03% ( = 26) resulted in death.

Discussion: The onset of the COVID-19 pandemic and increased emphasis on cleaning practices were likely contributing factors to the marked increase in exposures in 2020, which persisted through 2022. Cleaning practices that developed during the beginning of the pandemic likely persisted despite returning to more normal daily routines, which may explain the ongoing increase in reported exposures. Most reported exposures were unintentional, mild in symptomatology, and required the use of non-invasive therapies, if any.

Conclusions: Future efforts should focus on public education on the safe use of cleaning products to prevent exposure to toxic chlorine and chloramine gases.