A Comparative Study of Changes in Firefighters Occupational Exposure to Noise Catherine M. Fitzgerald, RN, MPH Elizabeth H. Maples, PhD
Disclosures
Firefighters Exposure to Noise 1 million American firefighters Exposure to hazardous levels of intermittent noise from: Sirens, air horns, fire truck engines, building alarms, SCBA alarms, motor vehicle accidents (equipment) Wearing hearing protection a challenge Exposure to noise is complex with considerable variation Other employment
Purpose Examine changes that have occurred in firefighters noise exposures in the same service over 15 years
Methods Birmingham City Fire & Rescue Service (BCFRS) 648 firefighters 30 stations in four battalions 27 pumpers (Fire Engines) 2 quint trucks 2 Bronto units 16 rescue units
Methods Personal noise dosimetry was conducted on 67 firefighters in 1997 and on 69 firefighters in 2012
Methods Sampled for full-shift - 24 hours Noise sources were identified and measured in 2012
Methods OSHA dosimeter settings Exchange rate: 5 db Frequency weighting: A Response: slow Criterion level: 90 dba Threshold: 80 dba
Methods IRB Approval Recruited firefighters from 6 fire stations Informed consent Demographic data Age Gender Length of Service Position on Engine
Results: Demographics Year n Male Female Mean Age (Years) Length of Service (Years) 2012 69 64 5 35 9 1997 67 65 3 37 11
Results: Overall Year n MeanTWA (dba) SD (dba) 95% C.I. (dba) p-value 2012 69 73.8 6.3 72.3-75.3 <0.001 1997 67 81.9 4.3 80.9-83.1 Year n Mean Peak (dbc) SD (dbc) 95% C.I. (dbc) p-value 2012 69 137.4 5.2 136.1-138.6 <0.001 1997 67 130.9 11.2 128.2-133.7
Results: Station Station n High or Low Call Mean TWA (dba) SD (dba) Range (dba) Mean Peak (dbc) SD (dbc) Range (dbc) Station 1 13 High 73.3 6.2 60.5-87.1 140.4 2.9 133.6-145.0 Station 6 11 High 71.1 2.6 67.3-75.9 136.7 5.1 127.3-142.4 Station 15 13 High 75.1 4.4 70.3-83.5 135.4 6.1 127.9-143.3 Station 19 13 High 75.8 7.7 65.7-88.1 138.5 3.6 131.4-142.3 Station 20 12 High 76.9 6.2 64.0-87.0 139.5 4.7 131.0-146.0 Station 32 7 Low 68.0 6.9 59.9-79.3 130.6 2.9 125.9-134.5
Results: Position Vehicle Position n Mean TWA (dba) 2012 n Mean TWA (dba) 1997 Engine Officer 12 72.7 12 81.26 Engine Driver 13 76.8 11 80.91 Engine Nozzleman 8 72.7 11 81.20 Engine Plugman 4 75.0 12 82.23 Truck Officer 2 76.9 3 81.41 Truck Driver 5 78.2 1 79.64 Truck Utilityman 5 77.1 2 79.55 Rescue Officer 8 71.7 3 86.06 Rescue Driver 12 70.1 4 87.41
Results: Siren & Air-horn Fire Apparatus LA eq (dba) (Outside Vehicle) Peak level (dbc) (Outside Vehicle) LA eq (dba) (Inside Vehicle) Peak level (dbc) (Inside Vehicle) Fire Truck 1 (Siren) 110.9 121.5 84.9 109.0 Fire Truck 1 (Air horn) 117.3 142.5 87.0 110.4 Fire Truck 2 (Siren) 112.0 127.5 81.1 100.8 Fire Truck 2 (Air horn) 106.9 136.3 87.3 106.1 Fire Engine 1 (Siren) 105.4 117.3 89.4 109.9 Fire Engine 1(Air horn) 104.3 118.1 81.0 107.8 Rescue Engine 1 (Siren & Air horn) 115.6 127.0 75.1 95.5 Rescue Engine 2 (Siren & Air horn) 115.8 128.5 82.2 97.9 Rescue Engine 3 (Siren & Air horn) 110.9 121.5 84.9 109.5
Results: Specific Noise Sources Specific Noise Source LA eq (dba) Peak level (dbc) Portable Diesel Generator 94.5 112.8 Personal Alert Safety System (PASS) Alarm 112.7 124.2 Positive PressureVentilation (PPV) Fan 104.4 123.8 Chain Saw 104.3 122.6 Fire Engine Pump 92.6 110.3 Leaf Blower 101.3 117.0
Discussion Significant reduction in the mean 8-hour TWA for noise within this group of firefighters since 1997 (mean difference 8.1 dba, p <0.001) Area monitoring revealed that firefighters can be exposed to intermittent high noise levels. The air horn of fire truck peak level of > 140 dbc. High call volume resulted in higher noise exposures. The stations with the highest average noise exposure are 2 of the busiest fire stations.
Discussion In 2012 the truck driver had the highest noise exposure (78.2 dba). The truck driver operates the pump during structural firefighting; the LAeq for the pump was 92.6 dba For 1997 the rescue driver had the highest noise exposure (87.41 dba) In 1997, firefighters were not enclosed in a cab, had direct exposure to the noise Location of siren has also changed
Discussion Exposure to loud noise is not only considered a health hazard but can also interfere with speech and communication Results from inside the fire truck and fire engine demonstrated a high noise level that has the potential to interfere with speech and communication.
Discussion In 2012, four (5%) of the dosimetry results were greater than the OSHA s action level of 85 dba, none of the measurements were above OSHA s PEL for noise In 1997, seventeen (25%) of the dosimetry results were greater than the OSHA s action limit only one of the measurements was above OSHA s PEL for noise
Discussion Results from our study demonstrate similarities with other studies Kirkham (2011)revealed a mean Leq and peak noise levels of 81.1 ± 4.8 dba and 137.1 ± 5.2 dbc respectively The mean Leq was higher than our study (mean Leq = 77.9 dba) Peak levels reported by Kirkham (137.1 ± 5.2 db) were very similar to the peak levels in our study (137.4 ± 5.2 db) Tubbs (1991) results ranged from 60-82 dba. The ranges of results from our study were higher 59.9-88.1 dba None of the dosimetry results obtained by Tubbs were above 85 dba
Conclusions Changes in firefighters personal exposure to noise in the last fifteen years A significant reduction in the mean 8- hour TWA for noise was observed between the two groups. Reduction may be due to changes in fire-engine design. Monitoring of specific noise sources - exposed to intermittent high noise levels - increased risk of noise induced hearing loss.
Limitations Small sample size Sampling conducted in one specific service only Exposure complex with considerable variation Samples not stratified These are the #s, but, what if?
Acknowledgements Birmingham City Fire & Rescue Service Lisa McCormick, DrPH Kent Oestenstad, PhD, CIH / Lynn Fancher Jonghwa Oh
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