Hazard Assessment and Respiratry Prtectin Reference Guide (OSHA) This infrmatin is frm the Occupatinal Safety and Health Administratin (sha.gv) What is silica? Silica is a txic respirable dust. Crystalline silica r free silica is mst ften fund in the frm f quartz in granite, limestne, sandstne, feldspar, sand and sme sils. What is respirable dust? Respirable dust is dust particles that are small enugh t penetrate int the small air passages (brnchili) and air sacs (alveli) f the lungs. These particles must be smaller than 10 micrns. Particles larger than 10 micrns get trapped in the respiratry system befre they penetrate these parts f the lungs. These larger particles get trapped in the nasal passages, thrat, trachea, larynx and larger airways (brnchi) f the lungs. Once trapped, these large particles are picked up by the mucus transprt system (mucciliary escalatr) and remved frm the respiratry tract, either as an expectrant r as swallwed material. What is silicsis? Silicsis is a respiratry disease r pneumcnisis that results frm breathing crystalline silica dust. The small silica dust particles irritate the lungs, which results in hardening, scarring and stiffening f the lungs. The severity f the disease depends n the amunt and size f the dust particles inhaled and the length f time ver which the expsure ccurred. What are the symptms f silicsis? There may nt be any signs r symptms in the early stages f the disease. The first symptm is usually shrtness f breath during times f exertin r exercise. Once the disease begins t develp, it can prgress even if the wrker is n lnger expsed t silica dust. What are the stages f prgressin fr the disease? The stages f the disease are: Chrnic silicsis is the mst cmmn frm f the disease. It is caused by verexpsure t dust cntaining small cncentratins f quartz, usually 30 percent r less, ver a lng perid f time (25-45 years). 1
Accelerated silicsis is caused by verexpsure t dust with a high cncentratin f silica. This frm f the disease is detectable by x-ray after nly ne severe expsure. The disease develps five t ten years after the initial expsure. Acute silicsis is caused by verexpsure t very high cncentratins f silica. Symptms develp within a few weeks t five years after initial expsure. This cnditin is rapidly fatal. Hw can verexpsure t respirable dust and silica be reduced? Use f engineering cntrls such as: Enclsing existing equipment cabs r installing new nes. Enclsing sputs in screening, mixing, bagging and ther peratins where cement, sand, rck r ther dusty materials are dumped, where practical. Installing water, mist r fg sprays t prevent dust frm escaping at the surce; such as rads, screening equipment, bagging equipment, mixing equipment and transfer pints, where practical. Installing dust cllectin systems t prevent dust frm escaping at the surce; such as screening equipment, bagging equipment, mixing equipment and transfer pints, where practical. Using ventilatin devices. When must respiratrs be used? When engineering cntrls are nt feasible. During such times as engineering cntrls are being implemented, but are nt cmplete. When wrking in psted areas where respiratr use is mandatry. What types f respiratrs may be used? Respiratrs designed t prvide prtectin against harmful respirable dust are classified as air-purifying respiratrs. Varius types r styles f air-purifying respiratrs are available, depending n the intended use and the envirnment in which the respiratr is t be used. Three cmmn types r styles are: Filtering facepiece. Elastmeric half facepiece. Elastmeric full facepiece. 2
There are three NIOSH-apprved filter series fr prtectin against harmful respirable dust. The three filter series are referred t as N, R and P. The levels f filter efficiency are 95 percent, 99 percent and 99.97 percent, against the mst difficult size particle t filter. N-Series Filters The N refers t n il in the air. This filter may be used fr slid r liquid particulate hazards that d nt cntain il and where the hazard is nly the particulate nature f the cntaminant. Generally, these filters can be used and reused subject nly t cnsideratins f hygiene, damage and increased breathing resistance. R-Series Filters The R refers t il resistant. This filter prvides sme prtectin against air that is cntaminated with sme particulate and has sme il present; hwever, this filter is nt the best alternative. This filter may be used fr any slid r liquid airbrne particulate hazard. If the atmsphere cntains il, this filter can nly be used fr a single shift r eight hurs f cntinuus r intermittent use. P-Series Filters The P refers t il prf. This filter is intended fr remval f any particulate, including il-based liquid aersls. This filter may be used fr any slid r liquid particulate airbrne hazard. Typical service life shuld nt exceed 40 hurs f cntinuus use r 30 days f intermittent use, unless hygiene r ther reasns warrant earlier replacement. Where il is suspected, but air samples have nt been taken t determine its presence, a P series filter shuld be selected. Hw d I dn a filtering facepiece respiratr? Place the filtering facepiece respiratr ver yur nse and muth, making sure the metal nse clip is n tp. (On sme mdels, yu must pre-stretch the straps befre wearing.) Pull the tp strap ver yur head until the strap rests n the crwn f yur head and abve yur ears. Pull the bttm strap ver yur head until the strap rests just belw yur ears. Using bth hands and starting at the tp, mld the metal nse clip arund yur nse t achieve a secure seal. Hw d I check the seal f a filtering facepiece respiratr? Each time yu dn a filtering facepiece respiratr, ne f the fllwing seal checks must be made. Psitive pressure user seal check fr nn-valved respiratrs. Place bth hands cmpletely ver the respiratr and exhale. The respiratr shuld bulge slightly. If air leaks between yur face and the faceseal f the respiratr, repsitin the respiratr and readjust the nse clip t btain a mre secure seal. If a prper seal cannt be achieved, cntact yur supervisr befre entering any area requiring Negative pressure user seal check fr valved respiratrs. Place bth hands ver the respiratr and inhale sharply. The respiratr shuld cllapse slightly. If air leaks between yur face and the faceseal f the respiratr, repsitin the respiratr and readjust the nse clip t btain a mre secure seal. Repeat the check prcedure. If a prper seal cannt be achieved, cntact yur supervisr befre entering any area requiring 3
Hw d I dn an elastmeric half facepiece respiratr? Place the half facepiece respiratr ver yur nse and muth, leaving the bttm straps unfastened. Pull the tp strap ver yur head, placing the head cradle f the strap n the crwn f yur head. Fasten r hk the bttm straps tgether behind yur neck. Adjust strap tensin t achieve a secure fit. Hw d I check the seal f a half facepiece respiratr? Each time yu dn a half facepiece respiratr, ne f the fllwing seal checks must be made. Psitive pressure user seal check. Place the palm f yur hand ver the exhalatin valve cver f the respiratr and exhale gently. The facepiece shuld bulge slightly. If air leaks between the face and the face seal f the respiratr, repsitin the respiratr and adjust the straps fr a mre secure fit. If a prper seal cannt be achieved, cntact yur supervisr befre entering any area requiring Negative pressure user seal check. If equipped with cartridges, place the palms f yur hands ver the cartridges t restrict airflw If equipped with filters, place yur thumbs nt the center prtin f the filters t restrict airflw The facepiece shuld cllapse slightly. If air leaks between yur face and the face seal f the respiratr, repsitin the respiratr and adjust the straps fr a mre secure fit. If a prper seal cannt be achieved, cntact yur supervisr befre entering any area requiring Hw d I dn an elastmeric full facepiece respiratr? Fully lsen all fur head straps n the full facepiece respiratr. Place the harness f the respiratr at the back f yur head and psitin the facepiece ver yur face. Starting with the neck straps and then the frehead straps, pull the ends f the fur straps t adjust tightness and achieve a secure fit. D nt vertighten the straps. Hw d I check the seal f a full facepiece respiratr? Each time yu dn a full facepiece respiratr, ne f the fllwing seal checks must be made. Psitive pressure user seal check. Place the palm f yur hand ver the exhalatin valve and exhale gently. The facepiece shuld bulge slightly. If air leaks between the face and the face seal f the respiratr, repsitin the respiratr and adjust the straps fr a mre secure fit. 4
If a prper seal cannt be achieved, cntact yur supervisr befre entering any area requiring the use f a respiratr. Negative pressure user seal check. If equipped with cartridges, place the palms f yur hands ver the cartridges t restrict airflw If equipped with filters, place yur thumbs nt the center prtin f the filters t restrict airflw The facepiece shuld cllapse slightly and be pulled clser t yur face with n leaks. If air leaks between yur face and the face seal f the respiratr, repsitin the respiratr and adjust the straps fr a mre secure fit. If a prper seal cannt be achieved, cntact yur supervisr befre entering any area requiring 5