“Peaker” electrical power plants operate only during periods of peak energy needs. Rapid fossil-fuel combustion ramp-up produces high emissions, and peaker plants are significant sources of CO ₂ and particulate air pollution. We evaluated whether residents living near a gas-fired peaker plant experienced increased pollution-associated emergency department/urgent care (ED/UC) visits associated with air pollution related to the “on” phases of peaker operation.

ED/UC visits for patients in a primary care practice serving the neighborhoods surrounding a peaker plant in Massachusetts were analyzed for 5 years (2017–2021) for visit diagnoses including respiratory and cardiovascular conditions, headache, and pregnancy complications. Daily exposure to peaker-related emissions using HyADS, an air-parcel trajectory model-derived unitless measure of exposure magnitude, was assigned by the zip code of each patient’s residential address. A case-crossover design evaluated the association between daily peaker exposure and cause-specific ED/UC visits, adjusting for heat index, PM _2.5 from other sources, holidays, and seasonality.

Average daily peaker plant exposure was 1.4 (unitless); large variability reflected plant intermittency (SD=16). Background PM _2.5 exposure was 8.5 μg/m³ (SD=6.4). Analyses included 2,310 ED/UC visits for assessed diagnoses among patients residing   30 km from the plant. Main analyses showed a positive association between short-term peaker emissions and increased risk of ED/UC visits for respiratory conditions (OR 1.044; 95 % CI 1.001–1.090). In addition, we found respiratory disease-related visits were elevated among the non-white group (OR 1.347; 95 % CI 1.034–1.755). There was no association noted between peaker emissions and visits for cardiovascular, headache, or pregnancy diagnoses.

The peaker plant worsened air quality when turned on. Although we did not observe consistent associations across all assessed ED/UC visit categories, there was a positive same-day association between modeled peaker-plant exposure and respiratory-related visits. Replacing combustion-driven peaker plants with renewable energy in densely populated neighborhoods could yield measurable global and local air quality-related health benefits.