Carbon Monoxide office exposure during construction

John S. MorawetzICWUC Center for Worker

Health and Safety Education

JMorawetz@ICWUC.org 513-621-8882

Loading Dock and Alley

There was a history of diesel trucks in alley adjacent to

loading dock.

Basic Office Layout

In the 1990s, Center staff had notified the previous building management about diesel emissions from the loading dock being noticeable inside the Center office space. This sign was subsequently posted in the alley adjacent to the loading dock.

Carbon Monoxide (CO)CO is a colorless, odorless and very toxic gas that is a common byproduct of incomplete combustion and improperly vented combustion devices. Unintentional and non–fire-related CO poisoning is responsible for more than 230,000 emergency department visits, 22,000 hospitalizations and approximately 450 deaths annually in the United States although rates appear to be falling recently. At lower levels of exposure, CO causes mild effects that are often mistaken for the flu (headaches, dizziness, disorientation, nausea and fatigue).

January 5, 2012Propane powered generator was needed for welding work. It was put on the loading dock with the door lowered but no venting. The temperature was app 23 over night; 30 during the AM.

With Loading door open Door closed and location of generator

Staff observed the generator on loading dockStaff retrieved CO direct reading instrument (GasAlertMicroClip XT; 4 gas detectors); range 0 – 500 ppmOSHA PEL 50 ppm -8-hour time-weighted average.NIOSH’s REL 35 ppm - 8-hour TWA and 200 ppm as a ceiling.ACGIH TLV 25 ppm - 8-hour workday.

Carbon Monoxide (CO) levels

10:45 AM Loading dock – 100 to 115 ppm

10:47 AMGenerator turned off and moved to alley

10:50 AM15 ppm – Instructor #1 office25-30 ppm in Classroom

1 PM CO levels persisted15 ppm – Instructor #1, 2 offices

Management notified and expected appropriate steps to be taken to minimize/eliminate future exposures.

January 6, 2012

Generator on loading dock with door lowered Vented through flex hose under loading dock door

CO on loading dock – 27 ppm at 11 AM

Flex hose location

Carbon Monoxide (CO) levels

11:00 AM Loading dock – 27 ppm Reception area – 15 ppm

11:05 AM 10-15 ppm – Instructor #1, #2 office25 ppm in Classroom

Carbon Monoxide (CO) levels

11:15 AM35-38 ppm around elevators OUTSIDE Office area

This demonstrates the ability of CO to migrate to other areas. The elevators are outside the Center area but one level below ground as seen below.

View from Center entrance along the long side of office area.

Entrance is just above basement level but one level below ground at the classroom and rear elevators area.

11:18 AMGenerator turned off and moved to alleyExterior Office door opened

11:35 AM0 ppm - Reception area

Epilogue

March 6, 2012Staff noticed welding materials entering buildingDirect Reading unit turned on2nd floor: 27 ppm; recalibration indicator onIt is discovered that generator is now operating in a construction room INSIDE the building on the first floor

First Floor Layout

10:15 AM - Generator turned off

Basement level monitored10:45 - all 20 ppmReception area, Elevator, Kitchen Hall

Second floor – 10:50 amOffice #3 – 11 ppmOffice #4 – 22 ppmHall – 22 ppm

11 AMGenerator moved to street with cables into the building.

Exposures reduced but still significant

ConclusionsSignificant exposures to a well known hazard continues to exist and OSHA standards may have been exceeded.

CO danger from companies using propane generators not well addressed.

CO can rapidly spread throughout office buildings.