Effectiveness of Dust Control Systems Tested for use During Masonry Restoration – The Sequel Michael R. Cooper, CIH, CSP, MPH RT Implementing Engineering Controls in Construction - Needs, Challenges, and Effectiveness June 4th, 2014

The local exhaust ventilation system evaluations being described are part of a four-year NIOSH-funded project to reduce exposures in construction

To reduce silica exposures during tuckpointing, LEV systems must be: Commercially availableCapable of capturing airborne dustUsed correctly

Our partnership identified tuckpointing LEV systems to evaluate Partnership ContractorsGovernmentUnionsResearchers Equipment Manufacturers

The partnership rated the following as the most important criteria when selecting systems for further evaluation: 1.Impact on productivity 2.Durability 3.User acceptance/compatibility with existing work practices 4.Blade visibility

While considering these criteria, the partnership selected tuckpointing LEV systems for further evaluation 1.Impact on productivity 2.Durability 3.User acceptance/compatibility with existing work practices 4.Blade visibility

The partnership selected from the grinders identified as most prominent in construction HiltiBoschMetaboMakitaDewalt

Arbortech AS170 Brick and Mortar Saw The partnership selected from seven tuckpointing shrouds ICS Dust Director Hilti Tuck Point Dust Removal Hood Dustless Technologies CutBuddie II Bosch Tuckpointing Shroud Joe Due Blades and Equipment Dust Mizer Danish Tool North America Tuckpointing Router Bit and Shroud

The partnership selected from 14 vacuums ICS Vacuums (4 models) Hilti VC 40U Vacuum Dustless Technologies HEPA Vac Bosch Airsweep™ 13 Gallon Wet/Dry Vacuum Cleaner with Power Broker Little Red Ruwac WNS 2220 Dustcontrol Vacuums (3 models) Ermator Vacuums (2 models) Tiger-Vac AS-400 HEPA

Four high ranking systems were tested, with and without LEV, in a controlled setting 1.Metabo grinder, ICS Dust Director shroud with Dustcontrol 2900 vacuum 2.Bosch grinder, ICS Dust Director shroud with Dustcontrol 2900 vacuum 3.Bosch grinders, ICS Dust Director shroud with Ermator S26 vacuum 4.Hilti grinder, Hilti shroud with Hilti vacuum

Test conditions and data collected were consistent between evaluations Used type S mortar after 28+ days curing Used filter (HEPA or 99.9%) recommended by manufacturer Conducted at least five trials per tool/control combination Randomized trial order to minimize bias Sampled for 16 to 26-minute with LEV, approximately half as long without LEV Sampled respirable silica sampling with BGI GK2.69 cyclone at 4.2 lpm Measured static pressure to monitor flow rate Documented mass of dust collected by LEV Documented linear feet of joints cut per minute

Using the Metabo grinder with the Dust Director shroud and DustControl vacuum reduced respirable silica exposures by 95.6%

Using this LEV system reduced exposures by 95.6% times REL 5.5 times REL

Using the Metabo grinder with the Dust Director shroud and DustControl vacuum reduced respirable silica exposures by 95.6% Mean, mg/m 3 (range) Hazard Ratio Metabo with LEV (n=5) ( ) 5.5 Metabo without LEV (n=5) 6.33 (5.06 – 7.26) 130

Using the Bosch grinder with the Dust Director shroud and DustControl vacuum reduced respirable silica exposures by 98.7%

Using this LEV system reduced respirable silica exposures by 98.7% times REL 140 times REL

Using the Bosch grinder with the Dust Director shroud and DustControl vacuum reduced respirable silica exposures by 98.7% Mean, mg/m 3 (range) Hazard Ratio Bosch with LEV (n=5) (< ) 1.8 Bosch without LEV (n=7) 7.23 (4.57 – 9.90) 140

Using the Bosch grinder with the Dust Director shroud and Ermator vacuum reduced respirable silica exposures by 97.6%

The Ermator S26 is rated to provide sufficient air flow to support two grinders

Using this LEV system reduced respirable silica exposures by 98.7% times REL 690 times REL

Using the Bosch grinder with the Dust Director shroud and Ermator S26 vacuum reduced respirable silica exposures by 97.6% Mean, mg/m 3 (range) Hazard Ratio Ermator with LEV (n=10) (0.288 – 2.27) 16 Ermator without LEV (n=10) 34.5 (4.73 – 89.0) 690

DAG 500-D grinder The Hilti system is a complete tuckpointing LEV system 129 cubic feet per minute Automatic filter cleaning every 15 seconds 99.9% efficient filter VC 40-U vacuum 5" Tuck Point Dust Hood DC-EX 125/5"C

Using the complete Hilti tuckpointing LEV system reduced respirable silica exposures by 96.6%

Using this LEV system reduced exposures by 96.6% times REL 220 times REL

Using the Hilti grinder with the Hilti shroud and Hilti vacuum reduced respirable silica exposures by 96.6% Mean, mg/m 3 (range) Hazard Ratio Hilti with LEV (n=5) ( ) 7.50 Hilti without LEV (n=5) 10.9 (3.46 – 31.4) 220

In addition, we performed limited evaluations with a new grinder shroud from Ermator

Test conditions and data collected were consistent between evaluations Used type S mortar after 28+ days curing Used HEPA filter as recommended by manufacturer Conducted at least three trials per tool/control combination Randomized trial order to minimize bias Sampled for 24 minutes with LEV and 10 minutes without LEV Sampled respirable silica sampling with BGI GK2.69 cyclone at 4.2 lpm Measured static pressure to monitor flow rate Documented mass of dust collected by LEV

Using the Bosch grinder with the Ermator shroud and Ermator S13 vacuum reduced respirable silica exposures by 96.1%

Using this LEV system reduced exposures by 96.1% 120 times REL

Using the Bosch grinder with the Ermator shroud and Ermator S13 vacuum reduced respirable silica exposures by 96.1% Mean, mg/m 3 (range) Hazard Ratio Bosch with Ermator S13 LEV (n=4) ( ) 4.6 Bosch without LEV (n=3) 5.85 (5.56 – 6.38) 120

Using Bosch grinders with the Ermator shrouds and Ermator S26 vacuum reduced respirable silica exposures by 97.8%

Using this LEV system reduced exposures by 97.8% times REL 3.6 times REL

Using Bosch grinders with the Ermator shrouds and Ermator S26 vacuum reduced respirable silica exposures by 97.8% Mean, mg/m 3 (range) Hazard Ratio Bosch with Ermator S26 LEV (n=6) ( ) 3.6 Bosch without LEV (n=6) 8.12 (4.04 – 13.2) 160

The highest flow rates at the tool were 79 percent of the manufacturers’ specifications for the vacuums tested

The average flow rates after use were 68 to 75 percent of our desired flow rate

The average flow rates returned to 85 to 102 percent of our desired flow rate after filter cleaning

The available tuckpointing LEV systems can be effective but there are challenges

Acceptance and effectiveness varies with the user

Moving the grinder toward the point of dust capture is required Dust Capture

Blade visibility and ability to cut both directions is important Dust Capture

Air flow rate at the tool must be maintained

Average exposure reduction was 97 percent but additional controls may be needed Respirable Silica (mg/m 3 ) NIOSH REL 10 X NIOSH REL

Questions? Michael R. Cooper, CIH, CSP, MPH