ObjectiveTo analyze the acute effect of nitrogen dioxide (NO₂) exposure on the incidence of coronary heart disease in residents of Yangzhou city, and to provide theoretical basis for the formulation of comprehensive prevention and control policies of coronary heart disease.MethodsData on the incidence of coronary heart disease in Yangzhou residents were collected from January 1, 2020 to December 31, 2022, and the atmospheric pollutants in Yangzhou during the same period [NO₂, fine particulate matter (PM_2.5), inhalable particulate matter (PM₁₀), sulfur dioxide (SO₂), carbon monoxide (CO) and the daily maximum 8-hour average values of O₃ (O₃-8) h)] concentration and meteorological data (average daily temperature, relative humidity), the effect of NO₂ on the incidence of coronary heart disease was studied by using time series analysis method.ResultsThe average dail concentration of NO₂ during the study period was (27.91±14.04) μg·m^－3. In the single-pollutant model, the number of acute cases of coronary heart disease increased by 4.73% (1.03%, 8.57%) for each IQR increase of NO₂ concentration (lag0 d). Two-and three-pollutant models showed that NO₂ was still positively associated with acute coronary heart disease after controlling for the confounding effects of other pollutants. Stratification analysis showed that the risk of angina pectoris increased by 4.16% (0.25%, 8.23%) for each IQR increase of NO₂ concentration (lag0 d). The risk increased by 5.77% (0.18%, 11.66%) in women; The risk was increased by 5.50% (1.32%, 9.85%) in residents aged ≥65 years. The risk of urban residents was increased by 6.35% (1.36%, 11.58%). The incidence of unmarried/divorced/widowed/living alone residents increased by 11.42% (2.77%, 20.81%); There was no significant effect on the risk of coronary heart disease in different seasons.ConclusionNO₂ exposure may increase the probability of acute coronary heart disease, especially angina pectoris. Female, ≥65 years old, urban, unmarried/divorced/widowed/living alone groups are more susceptible to increased NO₂ concentration.