We established a hypothetical acrylic acid leak accident scenario, conducted a health risk assessment of local residents, and compared an actual accident case and the hypothetical scenario. The exposed subjects were divided into four age groups, and a non-carcinogenic risk assessment was conducted for inhalation and soil ingestion. In the hypothetical scenario, 40 tons of acrylic acid were leaked in Ulsan for 1 h from 12:00 am on January 1, 2017, and in the actual accident case, 3 L of acrylic acid were leaked in Hwaseong, Gyeonggi Province, for 1 h from 11:00 am on March 5, 2020. The environmental concentration of acrylic acid was calculated using the dynamic multimedia environmental model. Non-carcinogenic assessment of the hypothetical scenario showed the hazard index exceeded 1 across all age groups, suggesting that a health risk is likely to occur due to inhalation exposure to acrylic acid resulting from a chemical accident. Hazardacute exceeded 1 until 2 h after the accident under the hypothetical scenario, indicating the likelihood of a health risk. Thus, we propose a methodology that can assess changing concentrations in a hazardous chemical leak from a chemical accident based on the time, place, the chemical’s behaviors in different environmental media, and the health risk posed by the exposure of the chemical to local residents in the area affected by the accident.