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IAQ and Noise tools Masood Ahmed MS, CIH, CRSP
Occupational Hygienist
OHCOW – South Central/Hamilton
Disclaimer……….
The purpose of this presentation is to provide information and education about noise. This presentation should not be used for
training or certification purposes.
Occupational Health Clinics for Ontario Workers (OHCOW) • An inter-disciplinary occupational health team:
• occupational physicians • occupational health nurses • ergonomists • occupational hygienists • customer service coordinators • leadership/administration
• Funded by MoL Prevention Services (from compensation premiums)
• BoD majority from organized labour
Regional Clinics:
Services:
1. Medical diagnostic service for workers who may have work-related health problems.
2. Group service providing educational and investigative support for joint health and safety committees and workplace parties.
3. Inquiry service to answer workplace health and safety questions.
4. Outreach and education service to make people aware of health and safety issues and promote prevention.
5. Research service to identify, investigate and report on illness, injury & disease trends.
Overview: 1. Physics
2. Health effects
3. Regulations
4. Measuring noise
5. Noise control
6. Other noise issues
7. Noise apps and tools
A little noise physics:
• Speed of Sound - 1100 feet per sec at room temp
(or 750 mph or 1200 km/hr).
• As frequency (pitch) goes higher, the wavelength
gets smaller (more cycles per second).
- at 100 hertz (Hz) the wavelength is ~ 10 feet
- at 1000 hertz the wavelength is ~ 1 foot
- at 10,000 hertz (10 kHz) wavelength is ~ 1 inch
• Human audible range – 20 Hz to 20,000 Hz
obligatory frequency diagram:
exit to frequency audio file
One wave is a complete cycle, the
number of cycles (waves) per
second is the frequency
http://amazing-space.stsci.edu/resources/explorations/groundup/lesson/glossary/glossary_terms/graphics/igt2_wvlngthfreq.gif
20 Hz – 20,000 Hz
Octave bands (Hertz)
http://www.sengpielaudio.com/TableOfSoundPressureLevels.htm
Decibels (dB)
http://www.sengpielaudio.com/TableOfSoundPressureLevels.htm
obligatory diagram of the ear:
http://www.tinnitus.asn.au/ear1.htm
….what we’re trying to prevent …
normal hearing cells damaged hearing cells
How it is measured?
progression of NIHL (noise induced hearing loss)
-10
0
10
20
30
40
50
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he
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dB
)
250Hz 500Hz 1000Hz 2000Hz 3000Hz 4000Hz 6000Hz 8000Hz
frequency
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pre-employment: worker starting first job
progression of NIHL (noise induced hearing loss)
-10
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he
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250Hz 500Hz 1000Hz 2000Hz 3000Hz 4000Hz 6000Hz 8000Hz
frequency
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after 3-5 yrs exposure
progression of NIHL (noise induced hearing loss)
-10
0
10
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40
50
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he
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dB
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250Hz 500Hz 1000Hz 2000Hz 3000Hz 4000Hz 6000Hz 8000Hz
frequency
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after 15-19 yrs exposure
progression of NIHL (noise induced hearing loss)
-10
0
10
20
30
40
50
60
he
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dB
)
250Hz 500Hz 1000Hz 2000Hz 3000Hz 4000Hz 6000Hz 8000Hz
frequency
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after 25-29 yrs exposure
What are the chances?
• depends on the intensity of the noise (how loud it is – measured in decibels (dBA))
• depends on the frequency – high pitch (treble) sounds more damaging than low (bass) sounds
• depends on the length of time exposed (yrs)
• depends on the age (natural hearing loss due to age - presbycusis)
presbycusis (age hearing loss)
-10
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10
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he
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250Hz 500Hz 1000Hz 2000Hz 3000Hz 4000Hz 6000Hz 8000Hz
frequency
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presbycusis (age hearing loss)
-10
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250Hz 500Hz 1000Hz 2000Hz 3000Hz 4000Hz 6000Hz 8000Hz
frequency
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High frequency loss happens first
stats
• “last five years, the annual costs for noise induced hearing loss claims for all sectors in Ontario exceeded $50 million per year,” (MOL 2014)
• the WSIB showed a steady increase in NIHL registered claims from 3653 claims in 2005 to 5416 claims in 2009 (WSIB, 2011)
• Masterson et al. (2013) found 18% of 1,122,722 worker audiograms collected from the NIOSH OHL Surveillance Project met the NIOSH criteria for NIHL
• Stekelenburg (1982) noted that: “… even if 80 dBA is taken as a time weighted average limit … 10% of the exposed population will not be protected against impaired social hearing caused by noise.” (page 408)
exit to Hearing Loss Simulator
What are the symptoms of NIHL (noise-induced hearing loss)?
• usually gradual (not noticeable) but can be immediate (if close to an “explosive” noise)
• tinnitus • ringing, buzzing, or roaring in the ears or head
• can be intermittent or continuous
• extremely annoying and not curable
• screening questions handout
How Much Noise is too Much?
• Anything above 65 dBA will eventually wear down your hearing.
• Years of exposure above 80-85 dBA will lead to a percentage of workers with a hearing disability (legally deaf).
• Trying to carry on a conversation over the phone with a background noise level of 60-65 dBA is very stressful.
Noise: Ontario OEL = 85 dBA ACGIH TLV = 85 dBA
http://www.cdc.gov/niosh/pdfs/98-126-b.pdf
Noise Induced Hearing Loss:
• WSIB recognizes noise-induced hearing loss (NIHL) compensation after an exposure of 90 dBA for 8 hrs/day for a minimum of 5 years or equivalent noise exposure;
• the policy also lists equivalent exposures as 84 dBA for 40 yrs or 28 yrs at 85 dBA
• Tinnitus is also compensable • Allowed NIHL
• Two or more years of sever tinnitus
• Diagnosed by a specialist
WSIB Hearing Loss Exposure Equivalencies
The minimum hazardous noise exposure of 90 dB(A) for 8 hours per day for 5 years has the following equivalencies*:
84 dB(A) for 40 yrs 89 dB(A) for 7 yrs
85 dB(A) for 28 yrs 91 dB(A) for 3.5 yrs
86 dB(A) for 20 yrs 92 dB(A) for 2.5 yrs
87 dB(A) for 14 yrs 93 dB(A) for 1.8 yrs
88 dB(A) for 10 yrs 94 dB(A) for 1.25 yrs
* ISO 1999-1990. Acoustics – Determination of occupational noise exposure and estimation of noise-induced impairment. Internat. Standard ISO 1990. 2nd ed. Geneva, 1990.
NIHL does not normally develop in less than 1.25 years.
Other than hearing loss health effects:
• “… what the non-auditory effects of noise are is still not certain. In general, the suspected effects include: • cardiovascular function (hypertension, changes to blood pressure and/or heart rate), • changes in breathing, • annoyance, • sleeping problems, • physical health and • mental health.
• This wide range of effects has led researchers to believe that noise has the ability to act as a general, non-specific stressor.”
http://www.ccohs.ca/oshanswers/phys_agents/non_auditory.html
How is noise regulated in Ontario?
Noise Legislation: O.Reg. Regulation 851, section 139
• employers take all measures reasonably necessary in the circumstances to protect workers from exposure to hazardous sound levels.
• protective measures against noise exposure include engineering controls, work practices and personal protective equipment.
• assessment of noise levels shall be done without regard to any use of personal protective equipment.
• every employer shall ensure that no worker is exposed to a sound level greater than an equivalent sound exposure level of 85 dBA, Lex,8.
O.Reg. 851 s.139 (continued)
• the employer shall protect workers from exposure to a sound level greater than 85 dBA, Lex,8 without requiring the use of personal protective equipment.
• personal protective equipment is only to be used if engineering controls, a) do not existence or are not obtainable; b) are not reasonable or not practical to adopt, install or provide
because of the duration or frequency of the exposures or because of the nature of the process, operation or work;
c) are rendered ineffective because of a temporary breakdown of such controls; or
d) are ineffective to prevent, control or limit exposure because of an emergency.
O.Reg. 851 s.139 (continued)
• if engineering controls can’t be used then workers shall wear and use personal protective equipment appropriate in the circumstances to protect them from exposure to a sound level greater than 85 dBA, Lex,8
• a clearly visible warning sign shall be posted at every approach to an area in the workplace where the sound level regularly exceeds 85 dBA.
• “An employer who provides a worker with a hearing protection device shall also provide adequate training and instruction to the worker in the care and use of the device, including its limitations, proper fitting, inspection and maintenance and, if applicable, the cleaning and disinfection of the device.”
Ontario Regulation 381/15
• New noise regulation, essentially the same as O.Reg. 851 s.139 except that it covers all workers in the province (not just those covered by the industrial regs (O.Reg. 851))
Column 1 Column 2
Sound Level
— in
Decibels
Duration —
Hours per 24
hour day
90 8
92 6
95 4
97 3
100 2
102 1½
105 1
110 ½
115 ¼ or less
Over 115 No exposure
previous table: current table:
Measuring noise:
• no measurement – everyone agrees its too noisy and let’s do something about it
• voice effort scale – do you have to raise your voice at an arm’s length away – if so probably over 80-85 dBA
• $50-100 type III sound meter (lots online) – can work well for area measurements (but no guarantee – calibration needed)
• dosimeter $1000-4000, does datalogging and acts as a sound level meter (usually downloadable) – measure individual exposures averaging over time
• octave band analyzer $3000-12,000, gives you noise frequency analysis usually used for acoustics and noise control engineering
Voice effort noise assessment:
voice level:
(1 meter away) normal loud very loud shouting
maximum
shouting
noise level:
(in dB(A)) 50 70 85 90 100
perception:
hazard level: slight
distraction
annoying,
unpleasant
some risk
of hearing
loss
medium
risk of
hearing
loss
high risk of
hearing
loss
Noise Measurement
There’s an App for that! • NIOSH has reviewed various
noise measurement apps and found that some do a reasonable job of measuring sound (and some not so reasonable)
• SPLnFFT
https://itunes.apple.com/ca/app/splnfft-noise-meter/id355396114?mt=8
http://www.cdc.gov/niosh/surveyreports/pdfs/349-12a.pdf
What next after measuring?
Prevention Opportunities
source > path > exposure > target > disease
check on effectiveness of controls
too late!!
Best Good Temporary
effectiveness of hearing protectors
ww
w.c
dc.
gov/n
iosh
/docs
/96-1
10/p
ers
onal.htm
l
effectiveness of hearing protectors
ww
w.c
dc.
gov/n
iosh
/docs
/96-1
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onal.htm
l
effectiveness of hearing protectors
This is not the permanent solution!
… nor even a very effective temporary one.
Preventing noise • purchasing policy (new machinery <75 dBA)
• vibration control (isolators, damping)
• quiet materials for conveyors, bins (noiseless steel, plastic coatings, etc.)
• silencers, mufflers, specially designed compressed air nozzles
• balancing rotating parts, avoiding harmonic frequencies, etc.
• avoiding impacts in process flow (slide instead of drop)
• enclosures, barriers, curtains
• sound absorbing acoustic wall/ceiling treatment
• increasing distance from source
• OHCOW worksheet “Doing something about noise”
Noise control principles & examples …
“Buy Quiet” • “To buy quiet in today’s market purchasers need a high level of understanding
of noise and noise control and must have a high degree of determination to achieve noise control in their workplace.
• Purchasers who successfully buy quiet seek out quieter machines and critically review the noise information supplied with them, which is often flawed.
• Such purchasers sometimes need to write, and check conformity with, their own specification for noise.”
Brereton & Patel, “Buy Quiet as a Means of Reducing Workplace Noise”, Acoust Aust DOI 10.1007/s40857-016-0051-x, online Mar 29,2016
http://www.cdc.gov/niosh/topics/buyquiet/
http://www.hse.gov.uk/noise/buy-quiet/index.htm
“Quiet” air guns
Compressed air nozzles & exhaust silencers
Tool Redesign
• Using a jacket over the tubular outlet in the jacket, the high frequency noise given off by a jack hammer can be partially shielded. The low frequency noise in the exhaust air is effectively reduced. The enlarged sections are between the barrel and the jacket functions as an expansion chamber.
Simple Noise Reduction
Vibration Transmission
Vibration & Damping
Vibration Transmission
Vibration isolators are made of various materials
Vibration Damping Coatings
… or line metal conveyors with old rubber conveyor belts
“Noiseless Steel”
Surface area transmission
Enclosure
Noise Barriers & Enclosures
Enclosure of Electric Motor or Compressor
Effects of Openings in Enclosures (hypothetical)
Degree of enclosure decibel reduction
full enclosure 60 dB
0.1% open 30 dB
1% open 20 dB
5% open 13 dB
10% open 10 dB
30% open 5 dB
50% open 3 dB
Noise Absorbing Baffles
Barriers to Prevention:
• Complacency: it’s always been that way, things will never change …
• Expertise: we need an expert with one of those fancy noise meters to come in and measure the noise …
• Expense: noise control is just too expensive!
• Shift the Blame: they should have worn their ear plugs …
Hearing Conservation Program
1. Noise surveys and data analysis
2. Education and motivation
3. Noise control
4. Hearing protection devices
5. Audiometric monitoring
The Noise Manual – 5th Edition
What about office noise?
• Background office noise usually comes from the ventilation system and is usually measured in an unoccupied office (or when things are quiet if occupied)
• The American Society of Heating, Refrigeration and Air-Conditioning Engineers (ASHRAE) has developed standards for background noise due to ventilation system to ensure adequate conditions for concentration and communication
Design Guidelines for HVAC-related Background Sound
2011 ASHRAE Handbook –
HVAC Applications (SI) Table 1 page 48.3
open-plan offices: Room Criteria (RC): RC ≤40 (equivalent to 45 dBA)
private offices: Room Criteria (RC): RC ≤30 (equivalent to 35 dBA)
Quality-Assessment Index (QAI): QAI ≤5 dB (N)
N= neutral (balanced sound spectrum) LF= rumble (low frequency dominant) LFVB= rumble (low frequency with moderately perceptible vibration) LFVA= rumble (low frequency with clearly perceptible vibration) MF= roar (mid-frequency dominant) HF= hiss (high-frequency dominant)
Cost-effective Open Plan Environments (COPE project)
• The National Research Council Canada (NRCC) has developed standards for open plan office environments (COPE)
• For noise the COPE recommendations are: • Ensure that all noise sources (e.g., ventilation systems, office
equipment and water coolers) do not exceed 40 dBA.
• The COPE research finding identified the optimum noise level (background & foreground) for open plan offices was determined to be between 42-48 dBA
http://irc.nrc-cnrc.gc.ca/pubs/ctus/63_e.html
Acoustics
• RevMeter Pro – an app to estimate the reverberation time in a room (≈ $7)
• ANSI S12.60-2002. Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools • “Unoccupied classroom levels must not exceed 35 dBA • The signal-to-noise ratio should be at least +15 dB • Unoccupied classroom reverberation must not surpass
0.6 seconds in smaller classrooms or 0.7 seconds in larger rooms”
https://itunes.apple.com/ca/app/revmeter-pro/id357421594?mt=8
http://www.asha.org/public/hearing/American-National-Standard-on-Classroom-Acoustics/
Noise Tools/Apps
Noise Legislation: O.Reg. 381/15
• employers take all measures reasonably necessary in the circumstances to protect workers from exposure to hazardous sound levels.
• protective measures against noise exposure include engineering controls, work practices and personal protective equipment.
• assessment of noise levels shall be done without regard to any use of personal protective equipment.
• every employer shall ensure that no worker is exposed to a sound level greater than an equivalent sound exposure level of 85 dBA, Lex,8.
solution: on-line calculator …
http://www.ohcow.on.ca/uploads/noisecalculator.xls
Sound Level
Duration
(85 dBA Lex,8)
Duration
(80 dBA Lex,8)
(in db(A)) (hrs/24 hr day) (hrs/24 hr day)
80¼ 24 7½
81½ 18 5⅔
82 16 5
83¼ 12 3¾
84 10 3¼
85 8 2½
86¼ 6 2
88 4 1¼
89¼ 3 1
91 2 40 min
92¼ 1½ 30 min
94 1 20 min
97 30 min 10 min
100 15 min 5 min
101¾ 10 min 3 min
104¾ 5 min 1½ min
111¾ 1 min 20 sec
114¾ 30 sec 10 sec
(hrs) (min)
Activity 1 45Activity 2 1 10Activity 3 3 30Activity 4 2Activity 5 2 35Activity 6 35Activity 7 5Activity 8
Activity 9
Activity 10
Activity 11
Activity 12
Activity 13
Activity 14
Activity 15
Activity 16
Activity 17
Activity 18
Activity 19
Activity 20
Activity 21
Activity 22
Activity 23
Activity 24
Activity 25
27.6%46.1%14.9%
2.0%7.9%
Dose
86.2
0.0%0.0%
0.0%0.0%
0.0%0.0%
132.0%
Total
838073
10074
Equivalent Noise
Exposure Level
Total
(%)
Dose
Time Weighted Average Calculator: This table calculates the 8 hr equivalent sound exposure
level for different noise levels and for specified lengths of exposure time. To use this chart, enter
the amount of time spent performing each activity and the corresponding noise level.
Exposure Time
8790
0.0%
10.67
Time
Noise Level
(dBA)
0.6%32.9%0.0%0.0%0.0%0.0%0.0%0.0%
0.0%
0.0%0.0%0.0%0.0%
Who can measure?
Noise Apps
http://pad2.whstatic.com/images/thumb/e/ee/Measure-Decibels-Step-2.jpg/aid1456686-v4-728px-Measure-Decibels-Step-2.jpg
https://itunes.apple.com/ca/app/splnfft-noise-meter/id355396114?mt=8
http://www.cdc.gov/niosh/surveyreports/pdfs/349-12a.pdf
https://www.youtube.com/watch?v=jGVN7m3Wd1M
SPLnFFT
SoundMeter App
https://itunes.apple.com/ca/app/soundmeter/id287615105?mt=8
app to measure reverberation
• RevMeter Pro – an app to estimate the reverberation time in a room (≈ $7)
• ANSI S12.60-2002. Acoustical Performance Criteria, Design Requirements, and Guidelines for Schools • “Unoccupied classroom levels must not exceed 35 dBA
• The signal-to-noise ratio should be at least +15 dB
• Unoccupied classroom reverberation must not surpass 0.6 seconds in smaller classrooms or 0.7 seconds in larger rooms”
https://itunes.apple.com/ca/app/revmeter-pro/id357421594?mt=8
http://www.asha.org/public/hearing/American-National-Standard-on-Classroom-Acoustics/
whole body vibration app
• free app which measures whole body vibration (WBV)
• well researched with published study to show validity
• i-Tunes store search for WBV
https://itunes.apple.com/ca/app/wbv/id797629017?mt=8
Online Audiometric test:
http://hearingtest.online/
Questions? [email protected]
