Chemical related incidents come in all sizes and locations.
It is not just accidents at chemical manufacturing facilities or transportation
centers that can result in emergency services responding to chemical incidents.
This was seen last week in a chemical response incident in a small town in
Pennsylvania last week. See the news story
here,
here,
and
here.
The Incident
Residents in a residential area complained about the smell
of chlorine (most familiar to people as the smell of bleach). Emergency
responders located the source of the leaking chlorine gas, a cylinder
inspecting and refurbishing shop
located
in an older residential area. The tank was sealed and the building
ventilated. Local residents were told to shelter in place until the chlorine
gas dissipated.
Four people were taken to the hospital ‘for observation’
according to news reports. It is not clear if they were employees at the
company (most likely to have significant exposure) or nearby residents. There
are no follow-up news reports so they were probably released after their
observation period was completed with minimal complications.
Chlorine
Chlorine is typically shipped as a liquid in pressurized
cylinders. When that pressure is released the liquid evaporates into a gas that
forms a heavy, yellow-green vapor cloud. Chlorine is a toxic inhalation hazard
(TIH) chemical that has been successfully used as a chemical weapon in WW I.
The allowable
exposure
limit (OSHA PEL) is 1 ppm. It
is detectable by its
characteristic odor by most people at 0.32 ppm. The concentration of most
concern is the immediately dangerous to life and health (IDLH) which is 1000
ppm. According to NIOSH exposure between the PEL and IDLG may lead to the
following symptoms:
Burning of eyes, nose, mouth;
lacrimation (discharge of tears), rhinorrhea (discharge of thin nasal mucus);
cough, choking, substernal (occurring beneath the sternum) pain; nausea,
vomiting; headache, dizziness; syncope; pulmonary edema; pneumonitis; hypoxemia
(reduced O2 in the blood); and dermatitis.
People with other existing respiratory problems will exhibit
symptoms at lower exposure levels than more healthy people.
The Business
The company has been in operation since 1946 (probably in
the same location). They take DOT rated cylinders used for the transport of
hazardous gasses and liquids and conduct the periodic safety inspections that
PHMSA requires for such cylinders. The testing requires that the tanks be
emptied, visually inspected and then filled with water. The tanks are then
pressurized and observed for signs of leaks and the expansion of the tank is
measured. The tanks that pass are then marked and recertified for hazmat
service in accordance with PHMSA regulations.
The
company’s web site
would seem to indicate that the majority of the tanks tested at the site were
propane tanks. The web site does indicate that other types of tanks are also
tested, including ‘low pressure’ (<900 amounts="" and="" are="" areas="" at="" chlorine="" disinfection.="" for="" o:p="" of="" other="" parks="" plants="" psi="" relatively="" small="" tanks.="" tanks="" that="" these="" treatment="" types="" typically="" use="" used="" usually="" water="">900>
The web site indicates that there is a service fee for
emptying propane tanks. There is no such fee listed for emptying chlorine
cylinders so it would appear that the company required those tanks to be
delivered empty. This would not be unusual for a small shop that did not handle
chlorine for other reasons.
What May Have
Happened
Unless the investigation by various government agencies
(principally state EPA and OSHA) reveals unsafe practices that result in fines,
the public will probably never hear the details of what happened at this
facility. Based upon news reports, I can come up with a reasonable scenario for
what might have happened.
The operator opening the cylinder would have been wearing
minimal personal protective equipment (hopefully a half-face cartridge respirator,
chemical goggles, a chemical jacket and industrial rubber gloves), expecting
the cylinder to be empty. When the tank began to off-gas a significant amount
of chlorine the operator would have been instructed to sound the local alarm
and evacuate the immediate area.
Since the facility did not apparently expect to actually
handle chlorine gas on site, there would probably not be ventilation systems in
place to scrub the chlorine from the local atmosphere. Ideally the facility
employees would move to an assembly area upwind of the facility and the local
fire department would be notified. A properly equipped Hazmat Team would
respond, seal the tank, ventilate the area, and conduct atmospheric testing
until the area was cleared.
From the news reports it does not seem that the notification
of the local emergency responders was made by the facility. This may have been
due to confusion on the site, or it may indicate that smaller chlorine releases
were normal enough that there was not an apparent need to report this incident.
If the facility were routinely handling cylinders with
significant residues of liquid chlorine in the cylinders, I would expect the
facility to have a lot more complex system in place for opening those cylinders
including a local ventilation system equipped to scrub the chlorine gas from
the atmosphere in the event of a release. I would define ‘significant residues’
as any visible liquid, but the EPA only
requires reporting
of spills over 10 lbs, so arguments could be made for any quantity between
those limits.
Emergency Services
Chlorine is a widely used hazardous chemical. As such, urban
and suburban fire departments should have at least minimal training in handling
chlorine related incidents. While the incidents of most concern will normally
be found at manufacturing facilities and along transportation (chlorine is routinely
shipped by rail and truck) routes, smaller incidents are not unusual.
It certainly appears from the news reports that the
responders in this case knew what they were doing and responded effectively.