Industrial Hygiene Approach to Airborne Pollutants

¶ … OSHA Technical Manual. I have not yet discussed this resource, but it is actually one of the foundational resources for the industrial hygiene practice. The specific article (SectionV, Chapter 3) outlines lead exposures in the construction industry. Lead is an airborne exposure risk. The article begins by defining an acceptable level of lead exposure, which is 50 micrograms per cubic meter of air (50 µg/m3). The OSHA approach to lead exposure is outlined -- it groups tasks into three categories that relate to their risk of lead exposure.

The article then discusses the hierarchy of controls. Engineering controls such as ventilation are at the top of the hierarchy, if the problem cannot be eliminated outright. Ventilation removes the airborne hazard, thereby reducing the exposure level. OSHA recommends other remedies such as using a less hazardous material, change in process equipment, or a change in process all as potential means of either eliminating or reducing the risk faced by workers.

Dilution ventilation is when the pollutant is spread throughout a larger area, and that area is regularly flushed with outside air. The pollutant's concentration in the air is thus diluted, to levels that are within the permissible range. A local ventilation system will capture the particles near the source and transport them to a collection system, thereby removing them from the environment. This approach is more costly but arguably more effective. A dilution system is more common, though, as it is cheaper and easier to implement, and can nevertheless bring the concentration level back down to the permissible levels.

Isolation is seen as another remedy, wherein the workers and the source of the risk are isolated. The lead exposure measures are time-weighted over an eight-hour period, so if a worker is only exposed for a very short time frame, then they are likely within the permissible bounds of exposure. So isolation can work, depending on the situation. But ventilation also removes some of the airborne lead toxins from the workplace environment, reducing them to permissible levels.

OSHA also has other suggestions that are lower on the hierarchy of controls, such a housekeeping and personal hygiene practices. Lead can built up on workplace surfaces, so if the surfaces are cleaned regularly then there is less risk of contaminants becoming airborne. It is a similar logic with personal hygiene -- if people clean themselves, then they can remove any pollutants that may have gathered on their skin over the course of a workday. This is a lower-hierarchy remedy, but one that can reduce one's exposure to these sorts of airborne pollutants. In some facilities, it might be valuable to provide shower facilities to encourage personal hygiene practices, if there is exposure to airborne pollution on a daily basis. There is also a discussion of eating facilities, because it is important that airborne pollutants like lead do not become ingested by workers.

The article then outlines some of the jobs and worksites that are at the highest risk of creating airborne lead exposure -- construction sites in particular are high risk. Detailed descriptions of operational and engineering remedies are provided. There are other professions at risk as well, including those who work with lead paint.