Hydrochloric Acid Spills in New York State - Hazardous Substances Emergency Events Surveillance (HSEES) 1992-1997

The HSEES Study

  • Respiratory irritation was the most frequent health effect (73%) reported in people injured during hydrochloric acid releases.
  • Of the 144 people injured during hydrochloric acid releases, 121 (84%) were transported to hospitals for treatment and release (80%) or admission (4%).
  • Human error caused 30% of the hydrochloric acid releases and 86% of the injured people.
  • 52% of injured people were employees, 35% were members of the general public and 4% were responders.
  • Most hydrochloric acid releases (40%) occurred in piping.
  • More than 4,690 people were evacuated following 30 hydrochloric acid releases.

Hydrochloric acid (HCl), is a colorless to slightly yellow liquid with a sharp, pungent odor. Also known as muriatic acid, hydrochloric acid is formed by dissolving hydrogen chloride gas in water. Uses of hydrochloric acid include scale removal in boilers and heat exchangers; neutralization of basic solutions; metals and general cleaning, laboratory procedures, and food processing. The American Chemical Society estimates that about 4 million tons of hydrochloric acid were produced in the United States in 1997.

Hydrochloric acid is corrosive to the eyes, skin, and mucous membranes. Skin contact may produce severe burns, ulceration, and scarring. Short-term inhalation exposure may cause coughing, hoarseness, inflammation and ulceration of the respiratory tract, chest pain, and pulmonary edema. Health effects following low level exposure may subside shortly after the person is moved to fresh air, but exposure to higher levels can cause life-long injury.

This fact sheet summarizes information on 129 hydrochloric acid releases investigated by the New York State Department of Health for the Hazardous Substances Emergency Events Surveillance (HSEES)1 project. The goal of this federal project is to reduce injury and death from accidental chemical releases through improved understanding of the causes. Learning about hydrochloric acid releases and how to prevent them can facilitate better training and improve the future safety of workers, responders and the general public.

Since 1992, the HSEES project has recorded information on 129 actual or threatened hydrochloric acid releases2 in New York State (Table 1). The quantities of hydrochloric acid released ranged in volume from 1 to 5,000 gallons, and in weight from 1 to 6,000 pounds.

1This document was supported by funds from the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) trust fund provided to the New York State Department of Health under Cooperative Agreement Number U61/ATU296968 from the Agency for Toxic Substances and Disease Registry, Public Health Service, U.S. Department of Health and Human Services.

2A threatened release qualifies for the project when the threat leads to an action (e.g., evacuation) that can potentially affect the health of employees, responders, or the general public.

Table 1: Summary of Accidental Hydrochloric Acid Releases New York HSEES, 1/1/1992 - 12/31/97

Table 2: Locations of 94 Reported Hydrochloric Acid Events at Fixed Facilities* New York HSEES, 1/1/92-12/31/1997

Twenty-five (19%) events involved injuries to 144 persons. In these events, 144 individuals were injured, three of whom died. The three fatalities resulted from trauma following a collision between two trucks, one of them transporting pool chemicals. Although the deaths were not from exposure to hydrochloric acid, they are included in the database because the employees were killed during an accidental chemical release from the collision.

Table 3: Medical Treatment Provided to Persons Injured During Accidental Hydrochloric Acid Releases New York HSEES, 1/1/92-13/31/97

Table 4: Injuries Following Reported Hydrochloric Acid Events New York HSEES, 1/1/92-13/31/97

Thirty events (23%) led to evacuations totaling more than 4,690 persons. The evacuation numbers are estimated minimums because, in some events, the number of persons evacuated or duration of the evacuation order was unavailable, even when the evacuation was ordered by an official. Fifty-six percent of the releases required a HazMat response (72/129).

The ninety-four hydrochloric acid events which occurred at fixed facilities are summarized in Table 2. The total of locations (100) exceeds the number of events (94) because six events are described by two locations, for example, piping and storage above ground. Thirty-eight fixed facility events (40%) occurred in piping which included leaky valves within pipes. Problems during piping, storage above ground, and material handling accounted for about two thirds (68%) of the fixed facility events.


Tables 3 and 4 summarize the injury data collected on the 25 events involving 144 injured persons. Fifty-two percent (75/144) of the injured persons were employees of the companies where the release occurred. Injured employees included both persons working at the location of the event and personnel employed nearby and injured during the release. Thirty-five percent of the injured persons (51/144) were members of the general public, four percent of the injured persons (6/144) were responders (emergency medical personnel, firefighters, police, etc.), and eight percent (12/144) were unknown. A few people (11%) were treated at the scene, but the majority of injured persons (80%) were transported to the hospital, treated and released.

The 144 injured persons sustained 216 injuries (Table 4). The injury total exceeds the number of injured persons because some people sustained more than one injury, for example, respiratory irritation and chemical burns. Thirteen persons sustained three injuries each, the maximum reported. The most prevalent injury, respiratory irritation, was reported by 105 of the injured persons (73%).

Table 5:Causes of Accidental Hydrochloric Acid Releases: Number of Events, Injuries and Evacuations New York HSEES, 1/1/1992 - 12/31/1997


Table 5 summarizes the causes of hydrochloric acid releases and the associated injuries and evacuations. Human error, which includes the subcategories of "improper mixing" and "overfill or delivery error," caused the majority of events involving injuries (52%) and the majority of injured persons (86%). Human error was also associated with the greatest number of persons evacuated (3,521) and the greatest amount of evacuation time (54,219 person-hours). Two large events in schools and one smaller event at a chemical company, resulted in the majority of injuries and evacuations attributed to human error.

Facility Type

Table 6 presents injury and evacuation data by facility type. In one major release, a chemical company evacuated a two block area but an exact number of persons involved was unavailable. By using 1990 census data, we estimated that approximately 1,327 people lived within 1/4 mile of the facility, and approximately 398 of these people were at home during the incident. Since the evacuation lasted four hours, the evacuation time in person-hours was calculated as 1,592 person-hours. This calculation is limited to residential properties and does not include any persons at work within the 1/4 mile area.

The greatest number of persons evacuated (2,787) and the largest loss of time due to evacuation (52,126 person-hours) occurred in schools. These incidents resulted from improper mixing of pool chemicals which released vapors that spread throughout the schools. Eight of the 12 school incidents led to evacuations and three of the 12 school events resulted in 19 injured persons (8 employees, 9 students, 1 responder and 1 unknown).

The greatest number of injuries occurred during an incident at a chemical manufacturing plant where a tank ruptured during the filling process. The cause of that incident was attributed partly to equipment failure and partly to human error.

The following are examples of releases that are included in the data:

  • During the delivery of 4,900 gallons of hydrochloric acid to a tank in a chemical plant, the tank ruptured. The tank rupture caused a nearby pipe to break and released a second chemical, sodium hypochlorite. Forty-three persons were treated at nearby hospitals and a two block area was evacuated for four hours.
  • During trash collection, a sanitation worker unknowingly picked up a one gallon container of acid and later crushed it in the hopper. While the acid was fuming, the truck pulled into the Department of Public Works garage. Two sanitation employees working in the garage were injured and required treatment at the hospital for respiratory irritation.
  • A school custodian was absent and called the substitute custodian to direct him to refill the chlorine container used for swimming pool treatment. The substitute custodian mistakenly added sodium hypochlorite to a drum of hydrochloric acid. The off-gassing forced the evacuation of fourteen hundred persons for the rest of the day. Fourteen persons were injured, all suffering from respiratory irritation and some with other injuries.
  • An employee of a restaurant mixed hydrochloric acid and household bleach to clean the floors. Nineteen persons (employees and patrons) were evacuated. Seven persons were transported to area hospitals where five were treated and released, and two were admitted. The other twelve were treated on the scene by Emergency Medical Services.

Table 6:Injuries and Evacuations following Accidental Hydrochloric Acid Releases at Various Facilities
New York HSEES, 1/1/1992 - 12/31/1997

Hazardous Substances Emergency Events Surveillance (HSEES) Project