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2.3 Hazardous Materials in Construction
Subpart D of the construction standard covers health hazards and chemicals in construction, including the Hazard Communication Standard, asbestos, MDA, lead, cadmium and process safety management.
| Term | Meaning |
|---|---|
| Article | A manufactured item, not a fluid or particle, with a specific shape that decides how it is used, and which does not release more than minute amounts of a hazardous chemical under normal use or pose a physical hazard. |
| Explosive | A chemical that suddenly releases pressure, gas and heat when shocked, pressurised or heated. |
| Hazardous chemical | A chemical that poses a physical or health hazard. |
| Physical hazard | A chemical that is combustible, a compressed gas, explosive, flammable, an organic peroxide, an oxidiser, pyrophoric, unstable or water reactive. |
| Trade secret | A confidential formula, process or information that gives the employer an advantage over competitors. |
| Workplace | An establishment, job site or project at one location with one or more work areas. |
Asbestos in construction
Asbestos is the general name for a group of natural fibrous minerals that are strong, flexible and resistant to heat, chemicals and electricity. In construction it is found in sprayed on fireproofing, pipe insulation, floor tiles, cement pipe and sheet, roofing felt and shingles, ceiling tiles, fire resistant drywall, drywall joint compound and acoustic products. Few asbestos products are installed today, so most exposure comes during removal and during renovation and maintenance of old buildings.
OSHA's construction standard divides asbestos work into four classes:
| Class | Work |
|---|---|
| I | The most hazardous: removing thermal system insulation and sprayed on or troweled on surfacing material. |
| II | Removing other asbestos containing materials that are not thermal insulation, such as resilient flooring and roofing materials. |
| III | Repair and maintenance work that disturbs asbestos containing or presumed asbestos containing materials. |
| IV | Custodial work: cleaning up asbestos waste and debris. |
For anyone exposed to airborne asbestos the employer must provide and make workers use protective clothing such as coveralls, head coverings, gloves, foot coverings and face shields or vented goggles where eyes may be irritated, plus respirators where needed. Workers who do Class I, II or III work for 30 or more days a year must receive medical examinations.
Workers are not always told that they are working around asbestos. Even single exposures to very low doses can do harm, and fibres can be carried home on clothing to families.
MDA (methylenedianiline)
MDA is a light brown crystalline solid with a faint amine odour. It is used mainly in making polyurethane foams, coatings, epoxy glues, spandex fibre, dyes and rubber. It enters by skin absorption, inhalation and ingestion. Short term overexposure causes fever, chills, loss of appetite, vomiting and jaundice, and irritates the skin, eyes and mucous membranes, and sensitisation can occur. Long term overexposure can cause cancer and damage to the liver, kidneys, blood and spleen.
Respiratory protection
Employers must provide respirators free of charge and make sure they are used:
- while engineering and work practice controls are being installed
- when those controls are not enough to bring exposure to or below the permissible limit
- when engineering controls are not feasible, for example in repair, maintenance and spray application
- in emergencies
Engineering controls must be used as fully as feasible. Respirators are the last line of defence.
Lead
Lead is a heavy metal that has poisoned workers for thousands of years. It can damage the central nervous system, the cardiovascular system, the reproductive system, the blood forming system and the kidneys, and a worker's exposure can harm the development of the worker's children. The general industry book (Part 10) describes the exposure limits and controls.
2.4 Process Safety Management on Construction Projects
The main concern of process safety management (PSM) is to protect workers from unwanted releases of highly hazardous chemicals. The standard applies to processes with more than 130 listed toxic and reactive chemicals in listed quantities, and to flammable liquids and gases in quantities of 10,000 pounds (about 4,536 kg) or more. It does not apply to hydrocarbon fuels used only as workplace fuel, or to flammable liquids kept in atmospheric tanks below their normal boiling point without chilling.
Construction contractors who work in covered facilities have special duties. The standard requires:
- Process safety information in writing before any process hazard analysis: the hazards of the chemicals (toxicity, exposure limits, physical, reactivity and corrosivity data, thermal and chemical stability, and the effects of mixing different materials), the technology of the process and the equipment.
- Operating procedures in writing, clear, consistent and communicated to employees.
- Training in the hazards, emergency operations including shutdown, and safe work practices, before assignment.
The general industry book (Part 11) lists all the elements of PSM.
A study aid, not published or endorsed by IOSH or OSHA. Laws and limits differ between countries.