Workplace, dust hazard

Public concern for the hazards of particle suspensions in the indoor and outdoor environment has produced regulations limiting particle concentrations and exposure levels. In the workplace, dust hazards are constrained by total mass concentration as well as concentration of specific toxic chemicals. In the ambient air, protection is stipulated in terms of total mass concentration of suspended particles andcertain chemical species, namely, lead and sulfate. Recently, measures of exposure have begun to distinguish between fine particles less than 2.5 fxm and coarse particles between 2.5 and 10 fxm. This separation relates to the ability of particles to penetrate the human respiratory system, and to different sources of fine and coarse particles. 

In its NEP, OSHA points out that for workplaces not covered by 1910.272, but where combustible dust hazards exist within dust control systems or other containers, citations under section 5(a)(1) of the OSH Act (the General Duty Clause) may generally be issued for deflagration (fire) or explosion hazards. National Fire Protection Association (NFPA) standards should be consulted to obtain evidence of hazard recognition and feasible abatement methods. Other standards are applicable to the combustible dust hazard. For example, if the workplace has a Class II location, then citations under 29 CFR 1910.307 may be issued to those employers having electrical equipment not meeting the standard s requirements. 

If a dust hazard is suspected in the workplace, the first step is to monitor the working environment to determine the exposure of the worker. One of the better methods of achieving this is for the worker to wear a portable sampling device, which gives a measure of the type of particles and their size distribution in the air immediately around the worker. Such devices usually sample at a typical respiration rate and velocity and some devices are designed to capture directly only the respirable particles (particles capable of reaching the alveoli) or the inhalable particles (particles capable of being inhaled). 

The second step in dealing with the potential dust hazard is for the results of the monitoring process to be compared with the accepted workplace standards for the particulate materials in question. If the concentration of respirable... 

In the HCS, combustible dust hazards must be addressed on labels and SDSs. Label elements are provided for combustible dust in the HCS and include the signal word warning and the hazard statement May form combustible dust concentrations in the air. For chemicals in a solid form that do not present a combustible dust hazard, but may form combustible dusts while being processed in normal downstream uses, the HCS allows the chemical manufacturer some flexibility in labeling requirements. The manufacturer or importer may transmit the label to the customer at the time of the initial shipment, but the label does not need to be included with subsequent shipments vmless it changes. This provides the needed information to the downstream users on the potential hazards in the workplace, while acknowledging that the solid metal or other materials do not present the same hazards that are produced when these materials are processed under normal conditions of use. 

Beryllium, beryllium-containing aUoys, and beryUium oxide ceramic in soHd or massive form present no hazard whatsoever (31). SoHd shapes may be safely handled with bare hands (32) however, care must be taken in the fabrication and processing of beryUium products to avoid inhalation of airborne beryUium particulate matter such as dusts, mists, or fumes in excess of the prescribed workplace exposure limits. Inhalation of fine airborne beryUium may cause chronic beryUium disease, a serious lung disease in certain sensitive individuals. However, the vast majority of people, perhaps as many as 99%, do not react to beryUium exposure at any level (33). The biomedical and environmental aspects of beryUium have been summarized (34). 

Diatomaceous earth, widely-known and long-used as a filteraid in process and waste filtrations, has a high microcrystalline silica content. As well as being a respiratory hazard in the workplace, the silica is being scrutinized in some jurisdictions as a potentially hazardous dust in landfills in which spent filter cakes are deposited. 

Compliance with the written program can be verified during the walkaround by personal observation and employee interviews. If respirators are required to be worn in the workplace or respirators other than dust masks are worn by voluntary users, a written program is required. An overexposure is not required to cite. Discrepancies between the written program and implemented work practices at the worksite should be cited. Use of a elastomeric or supplied-air respirator, even when voluntary on the part of the employee, will require the employer to include all elements in a written program that will make sure that there is proper use of these respirators so that they do not create a hazard. 

Air cleaning (dust collection) can be cost effective for LVHV systems handling valuable dusts. Care must be taken when handling potentially toxic dusts from air cleaners. Regular, routine reconditioning of fabric filters (e.g., by automatic shaking or pneumatic pulsing) is impottant. This can be accomplished on a set maintenance schedule or as a function of pressure drop across the fabric filter. It is not recommended to recirculate airflow back to the workplace because of the low air volume and potential hazards in the event of filter failures. 

The hazard from lead is very high, particularly in conditions where the general standard of hygiene is low and lead dust is allowed to accumulate or lead fume is emitted uncontrolled. The recommended permissible limit for concentration of lead in the workplace for lead dust and fume is 0.15 milligrams per cubic meter of air. 

Dust in the workplace is often considered to be merely a nuisance that has to be cleaned up once in a while. In some cases that s true. In others, however, as we have seen with lead, dust can be a significant source of hazard. The problems associated with dust will be considered in Chapter 9. 

The American Textile Industry Involvement with cotton dust as a workplace hazard began over ten years ago with Industry studies to determine whether the Industry had such an Illness problem. Then followed major dust removal and ventlllatlon efforts. The Industry developed a work practices and medical surveillance program which was presented to OSHA. 

Inhalation of iron(II) oxide fumes or dust is considered a hazard and can cause throat and nasal irritation. High levels of exposure may lead to a condition known as metal fume fever, a workplace exposure illness that causes flu-like symptoms. Continued exposure at high levels can have more serious effects, including a disease known as siderosis, an inflammation of the lungs that is accompanied by pneumonia-like symptoms. 

Sodium silicates are strong irritants to the skin, eyes, and respiratory system. Prolonged exposure to sodium silicate dust, powder, or liquid may cause inflammation of the skin, eyes, nose, and throat. More serious symptoms may include difficulty in swallowing, burns inside the stomach, damage to the mucous membranes, rapid heartbeat, hypertension, shock, severe damage to the lining of the gastrointestinal tract, various types of cancer, and death. These hazards are of concern primarily to workers who come into contact with sodium silicate in solid or liquid form in the workplace. 

In 1987, the atmospheric limit value for wood dust (the TRK value) was established at 2 mg/m for new plants and 5 mg/m for old / existing plants. Since 1996, the 2 mg/tn value,measured as inhalable ( E ) dust (Technical Rule for Hazardous Substances N° 900), applies to all workplaces where wood dust is generated. At European level, the limit value for hardwood dust is 5 mg/m (Coimcil Directive 1999/38/EC). 

Surveillance of Compliance with OELs for wo( dust over recent years. Thore are several reasons why worlqilaces where wood dust is generated have been monitored quite intosively since the md of the 1980s. Probably most important reason has been the negative list of the TRGS 553. This imphes a threat that the Committee of Hazardous Substance will witibdraw workplaces and / or machinery mentioned in tins list if no da is supplied when the list is revised. It is... 

---