Airborne concentrations of asbestos in non-occupational environments

Area of Science:

• Environmental Health
• Occupational Hygiene
• Asbestos Risk Assessment

Background:

• Asbestos was widely used in building fireproofing, leading to potential occupant and maintenance worker exposure.
• Litigation-driven sampling provides data on asbestos concentrations in diverse building types.
• Operations and Maintenance (O&M) Programmes aim to control asbestos exposure risks.

Purpose of the Study:

• To determine airborne asbestos concentrations in buildings and assess occupant exposure risk.
• To evaluate asbestos inhalation risk for maintenance workers under O&M Programmes.

Main Methods:

• Air sampling in over 300 buildings analyzed via transmission electron microscopy (TEM).
• Analysis of maintenance logs (1991-1992) detailing worker exposures and protective measures.
• NIOSH 1400 protocol using phase contrast microscopy (PCM) for maintenance worker samples.

Main Results:

• Building occupant exposure (90th percentile) generally below 0.0005 f/ml (>5 microns).
• Maintenance worker exposures varied, with an 8-h time-weighted average (TWA) of 0.0149 f/ml (>5 microns) in one commercial building.
• Modest O&M precautions (wet methods, HEPA vacuums, respirators) were employed; negative pressure containment was not used.

Conclusions:

• Asbestos exposure risks for building occupants are very low at measured concentrations.
• Maintenance worker exposures, while higher than occupants, remain within low-risk levels with implemented O&M practices.
• Effective O&M strategies can manage asbestos-related inhalation risks in buildings.