Occupational Noise Survey - Pdf Download - CiteHR
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Dear Dipil,

You are correct.

The work place monitoring is done for TWA (Time weighted Average) for 8 Hours.

This is true for exposures of dust as in your case also becomes critical for exposures to various chemicals. Such monitoring is called workplace monitoring as per Factories Act Second Schedule.

There is another term called STEL (Short Term Exposure Limit) which is for 15 minutes. The STEL limits are slightly more than TWA limits.

The exposure of the operator is for TWA or for STEL is decided by what he does.

To explain this situation the following example would be useful.

If we take a case of pollution on road signals, the traffic police is exposed for 8 hours as he does duty all the time in polluted area, however a vehicle passing through that signal point the driver is exposed only for 15 minutes, hence here for the driver STEL would be applicable.

In the above example of noise monitoring according to my view, as long as the process does not change, the noise level may not change. More over the noise is usually measured at 1 meter distance from the source. This should be OK.

Request the members having exposure to continuous process plants and cases of variations in noise levels to share their experience.

Thanks & Regards,

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@ Sudhir..You are confusing the discussion. Clearly here the discussion is only regarding noise survey. In 2nd Schedule of the F.Act 90 dB is TLV (TWA) for noise. No STEL has been prescribed for noise in the Schedule
Dear Sir
Nice to see your active participation in the discussion under this forum title after a long time...
Can you tell me the ideal way of monitoring noise? how it should be done? What should be the measuring equipment to be used?

Dear Sir
Thanks for your reply.
In the case of dust I think personal monitoring is of 8 hours is doing by most of the organizations... But when comes to noise I people are not doing this s hours monitoring... May be going to a particular location with the sound level meter and measuring and coming back...
In the example you bring about the Traffic Police man, I would say we should go for continuous monitoring (TWA for 8 Hours) than checking it for short term... Cause traffic may be different time to time... May be more trucks plying than cars or two wheelers, hence sound level also fluctuating one...
Then you have mentioned about the measuring distance from source is one meter... I read somewhere it should be measured at a distance of 5 & 10 meter from the source of noise... I don't know whether it is authentic or not? Is this distance is mentioned anywhere in any act?? How we should do perfect monitoring of noise???

@ Dipil
Personal dosimeter is probably best idea. Equipment has to be of standard brand ( I have no idea but that can be looked for. I have simple equipment donated to us by our US friend). What is probably more important is CALIBRATION. At least every 6 months it should be calibrated and if you are not using it regularly then before every use it should be calibrated. As for at what distance it should be measured,there is no legal standard available and we should go by standard practice. I have lot of literature which I can refer and come back with precise reply but that may need some time. I suppose ACGIH manual is available on net which should be referred.
Dear Sir
Thanks for your reply..
I will check for ACGIH manual online...
I will also check how our environment cell conducting these monitoring and will see is there any opportunity for improvement...
hi murdhar..
there will be places wherein PPE are in use currently..
however what we need to remember is these are actually business opportunity areas.
there are firms investing in R&D bringing out newer technologies/ devices/ even robotics ...
i have worked with leading conglomerate in middle east..
one of our division was glass manufacturing...
we switched to automatic probes/ climate controller enclosure even though it was a very expensive proposition.
Dear Friends,

For some time I was actively participating in the discussion. Finding there is not many enthusiastic safety professional especially youngsters to discuss safety matters seriously I kept away from the forum. Safety is a serious matter. It is mostly a matter of life, health and death. Many a topic which is no way relevant to safety also comes up in the forum wasting precious time. However again today by chance I went through the topics under discussion and found NOISE being discussed.

Noise is a serious issue for industrial hygienist. For Certified Industrial Hygienist (CIH) Examination conducted by ABIH, of seventeen topics noise is one. Where hygienist is not available safety personnel will have to deal with it.

Our safety people Ė are they trained to deal with industrial noise? I very much doubt. We can see there is not much in their curriculum for even in their safety diploma course. Few interested ones probe and collect some information from here and there. Equipped with this information they manage ???

Time is changing. It is essential that industries deal with noise with all its seriousness. In order to convince managements about dealing with noise problems there is only one agency - the Industrial Hygienist/Safety man. It involves lot of expenditure and effort to have a noise conservation program. Without getting convinced about its seriousness management will not support it. If a proposal is put up; management will have lot of queries over it to approve expenditure. Ask yourself! Are you prepared to give convincing replies to these queries?

If not we will have to study about noise and get equipped with sufficient information.

Lets us start with a few questions.

1. The reference sound pressure is defined as- ?

2. At what frequency are A, B, and C weighting scales equal?

3. A type II sound level meter has an accuracy of - dB

4. Determine the total percent dose for the following noise measurements:

1 hour @ 85 dB

3 hours @ 95 dB

0.5 hours @ 105 dB

5. What is the cumulative resultant noise exposure (approximately) for three machines with the following noise ratings (hint: use the short cut method)?

1. 89 dB

2. 92 dB

3. 99 dB

6. What is the SPL at 200 feet if the SPL at 20 feet is 103 dB?

7. At 30 feet away one piece of equipment registers a SPL of 80 dB. A second piece of equipment at 30 feet away registers a SPL of 85 dB. What is the SPL when both units are operating at 30 feet away?

8. An Octave Band analyzer is defined as an instrument to determine

9. Two separate noise sources of 98 dBA and 96 dBA respectively are installed and operated together. What is the combined noise level?

10. Theoretically, the minimum number of sound pressure level measurements needed to determine the sound power output from non-directional noise source in a free field is -?

11. Which classification of noise is described as: sharp burst of sound, lasting less than 0.5 seconds, and repeated less than 1 time per second?

12. What is NRR?

13. Why is audiometric testing required?

14. Where are the Noise Dosimeters to be clipped?


Kesava Pillai
Dear Sir,
Your post is eye opener.
Usually in an industry except for the DG Set noise, other work place noise cases are delt with PPEs.
A very few organisations follow the practice of Job Rotation, Medical Examination.
The need of above questions is not felt.
Your reply is genious and request to post the answers too.
Warm regards,
Good Morning Mr.Kesav pillai,

Nice to see you after very long time Just take a look on below links we didn't get answer but itís very important/ interesting topic to our EHS professionals - EHS Newsletter, Safety Campaign, and Gas cylinder. Take a look on it.




Let's go to topic Sir, Most of topic we had a very serious discussion in our forum and got great solution on our forum. I agreed your one of the best EHS profession ever seen then u shared tons of technical matters with us on lot of threads.

No one ready to share his experience specially seniors (Iím not mean all seniors) with youngsters. I am preparing for CSM from NASP and CSP from BCSP. I asked to one of my senior who holding the CSP provide me the materials because itís too expansive Volume Ė I and Volume Ė II costs 2000 $ + but he simply said he donít have materials (even i asked him Iíll pay for it). Here in our forum one of our member said to me will send the document/file; since last August, 2011 still he saying will send you may it takes him only 10 min to post the courier but?

No one not ready to share his knowledge specially who having extraordinary dataís with him. You can upload one file in our forum within a week at least more than 500 people downloading the file but not more than 10 people putting his comment then what about 490 persons?

Iím a certified OSHA 311 fall protection certificate holder but I know still Iím not able to answer some technical questions itís not mean doesnít know about fall protection still Iím learning please help your juniors like us; share your valuable experience with us, educate and guide us to improve our skills & qualification to save our precious human lives as a EHS professional.

Again, please whenever you get time share your view ask some questions on various topic participate on our thread it will help us to improve our skill on EHS side.

Keep on touch.

Note; We have a CEO visit in our camp really very busy as soon as getting time will try to answer your questions.
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