Industrial Hygiene in Construction

I’ll admit it. My elevator pitch is not the best. I have a hard time trying to briefly describe what I do as an industrial hygienist. I usually answer the question with a recent example of a interesting project.

What would you hire an industrial hygienist for? Well, this article describes exactly when you would hire one. I bet the haz mat crew has at least one hygienist investigating this concern.

AIHA has published video on what IHs do and our job function (s). They did a much better job than I could have done, but, the video is NOT as exciting as real-life.

Background: A new client recently had an OSHA health inspection (industrial hygiene). He received citations stemming from overexposures(they found levels above the PELs) to airborne particulates.

The company wondered what to do next. Here were my suggestions:

• Fix the problem. You will need to comply and assure that your employees aren’t overexposed. Even if the inspection made you upset, use your energy to make the situation right. Focus your energy on removing the hazard, not complaining about how you were treated.
  • Engineer the problem out. Remove the hazard. If not,
  • Change your policies so no one is further overexposed. If you can’t fix it by the this, or the above method, then,
  • Provide personal protective equipment to affected employees.
• Request the full inspection package. – this will include the officer’s field notes, interview questions, observations and sampling methodology.
  • look through these documents carefully
  • keep them for your records
•  Informally appeal the citations.
  • at the appeal show them you have complied/changed
  • ask for a reduction in fines (it never hurts to ask)
  • ask to group the citations together – instead of citation 1 item 1a, 1b, item 2, etc. ask to narrow it down to just one
  • bring any additional information which supports your side and/or the changes you’ve made (including training docs, programs, policies, etc.)
• Resample the areas.
  • make significant changes to these areas. Then,
  • hire an industrial hygienist to perform additional sampling in these areas
  • ask them to document the changes you have made to reduce the exposures
  • review this with your safety committee & those affected

You already knew it. There is a lot to do in industrial hygiene. At times this occupation feels like a safety middleman trying to keep people out of trouble. Occasionally I’m rewarded with really helping someone. In the United States, there is still a lot of occupational hygiene issues and concerns. Overseas, particularly in developing countries, there is even more.

It is hard to obtain accurate exposure data, or illness rates, from these underdeveloped countries. (How does a village of 1,000 people in Kenya report that they’ve had lead exposure to battery recycling?) How these exposures are brought to light is by either a massive death (# of people, quickly) or, someone with a camera able to actually photograph the pollution. As we know, what it looks like doesn’t necessarily correlate with hazardous levels of exposure. But, in some cases, it’s pretty obvious.

I ran across this photo story on pollution (The Guardian, UK). They estimate 125 million people are exposed to industrial pollutants (generic term, I know). This makes occupational related exposures a health risk as big as TB and Malaria! The article is based upon a report from the Blacksmith Institute which included this map of the worst pollution with associated disease.

How does this apply to construction? The worst offenders are lead (Pb) (and other metals), and asbestos.

What can you do? Here’s their recommendation, from the report (p50):

Developing countries need the support of the international community
to design and implement clean up efforts, improve pollution control technologies, and provide educational
trainings to industry workers and the surrounding community

Another NPR article about lead poisoning can be found here.

When measuring by air sampling for a job task, or an employee’s personal exposure, how many samples should you take?

Sometimes it is easier to place one filter cassette (or media) on the employee for the duration of their day.  At the end of the shift, you collect your equipment, mail it to the lab, and they spit out a 8-hour time weighted average (8-hour TWA). This is simple and easy to understand.

However, if you have the time and resources, it is usually beneficial to obtain multiple samples throughout the day. Taking multiple samples allow you to:

• obtain peaks, lows, and anomalies.
• look at: set up & clean up activities (separate from daily tasks)
• measure multiple employees doing the same task (to better capture the job task)
• calculate your own time weighted average
• capture short term exposure levels (STELs), or excursion limits *
• choose appropriate PPE for short duration tasks
• determine if employees are “falsifying” the data (skewing the data high or low)
• reduce filter overloading (in some cases)

There are some reasons NOT to obtain multiple samples:

• collection limit constraints (sometimes the method of sampling does not allow for this type of multiple sampling)
• it can be costly
• it is very time consuming (and nearly impossible, if you have multiple pumps on multiple employees throughout the site)
• difficulty interpreting the data (the math, the inferences, etc)

If you are hiring an industrial hygienist to perform air monitoring, ask about multiple samples. It might be slightly more expensive, but the information and data might be worth the cost.

*ACGIH recommends that if the compound does not have a STEL, all airborne levels should not exceed 3x the 8-hour TWA as an excursion limit.

The first question is, “why is this useful?“. Well, generally speaking, it is helpful to know if you are getting bare-minimum airflow, or if you are creating a wind tunnel on your project. Since many construction projects are not able to mobilize until the last minute, it is useful to make some rough guesstimates and calculate the airflow in the room. One squirrel-cage fan isn’t going to ventilate a warehouse, and 5 of them in a manhole will make welding impossible.  so…moving on.

Air changes per hour (ACH) is a function of the room size and the airflow into/out of the room. It is simply the number of times the volume of air is changed out over a one hour time period. One reason this calculation is so attractive to use is because there are recommended exchange rates for different environments. Some of them can be seen in the picture, the rest can be found here.

To calculate you must know:

• A = Volume of room in cubic feet (ft3)
• Q = Air flow of your fan (s) in cubic feet per minute (CFM)

Rather than reinvent the wheel Wiki has a good summary.

Caveat/Disclaimers. There are quite a few…so be careful.

• Mixing. The air never really mixes when you are exchanging air in this manner. It is dilution ventilation. So,
• Never use this method for any hazardous source, and
• Never use this for any carcinogens (asbestos, benzene, etc).
• Airflow into & out of the space is required, and is never ideal. Make sure there is space for the air to actually exchange.
• Make sure your fans work properly and do provide the manufacturers output.

After performing an industrial hygiene survey (air monitoring), have you considered when you should resample? Here are some considerations that might help you in determining when.

• Are there specific rules that state when you must resample? For example, the construction lead standard (1926.62) states that you must resample yearly (or actually, that you can only use relevant results for one year).
• Has the process changedsince the last time you sampled? This one is hard to determine. Lot of things can change air monitoring results, here’s a “starter list” of things that can change a process.
  • Different employee?
  • Time of year? Summer versus winter? (closed up/open and humidity)
  • Is a new tool in place?
  • Has the ventilation changed?
  • Have new controls been put in place? (administrative, systems operations)
• Has the product changed? Check the safety data sheet (aka MSDS).
• Are more (or less) employees exposed to this hazard? This might change some assumptions you have made about your risk.?

If you have air sampling performed, make sure you have a written report of your findings. Laboratory results without an explanation of how they sampled, where, # of employees, process description, PPE used, safety data sheets, etc….is worthless. You may remember is well enough, but OSHA will have a hard time believing that it is a similar exposure the next time you do the “exact same thing”.

Having this report and sharing it with the employees will fulfill (part of) the hazard communication standard requirement to employees.

When performing air monitoring it can be useful to take multiple samples on the same individual throughout the day. Here are some reasons to change out the filters:

• build up of dust on filter – can cause overloading
• break-out the exposure data. Morning versus afternoon, or by job tasks, or the physical area the employee is working in, controls vs. no-controls, etc.
• if you question the employees motives. If you think the employee might skew the results, multiple samples might give you better control- or at least tell you if one is way-out-of-line.

Once you have your data results, how do you combine them?

If you’re taking particulate (dust, lead, cadmium, silica, etc) and you have the concentrations (from the lab) here is what to do.

1. note the time (in minutes!) and the concentration results (mg/m3, ug/m3, etc) for each sample
2. multiply the time and concentration for each – then add each number together
3. finally, divide the above number by the total number of minutes sampled. This is your time weighted average (TWA).

Simple?! Yes. …And it’s really easy to make a mistake too. Check your math, and then eyeball the results and see if they make sense logically.

Here’s an example:

Andrew took three samples during one shift while Shelley was rivet busting through leaded paint. The first sample (118 minutes) was reported as 6.8 ug/m3 of lead, the second was for 245 minutes and had a concentration of 18 ug/m3. The last sample was taken for 88 minutes and was reported a level of 29 ug/m3. The overall results is 17.2 ug/m3 for the total time sampled. (Side: if you sampled for their entire exposure, and they worked longer hours, you could add those hours (assuming zero exposure) into the final time-in step three)

See the math below:

Do you measuring dust on your project/ workplace? If you are a safety professional and you are self-performing this type of sampling here are some tips.

• Measure for the full shift (including prep and clean up) – clean up can be the worst
• Depending on the type of dust, you might need to measure by either respirable, or inhalable (IOM) methodology.  -more on this at a later date
• Watch the dust filter build-up. You might want to change the filter out so as not to overload the cassette. Especially during clean-up.
  
• Have you checked for metals? Many types of dust can contain metals. Ask the laboratory for assistance.
• Consider the placement of the sampling filter. Do you want it downwind? On the collar? Is it on the best employee for sampling?
• Do you perform an area sample? These are not usually recommended, but sometimes they can give you great information.
• Information. Capture all the information that might be important to this sampling. Time, humidity, temperature, controls (or lack of), open doors/windows, employee practices, etc.

As I have said in an earlier post, some OSHA, EPA, and MSHA rules are a good fit. They blend well with health research, scientific technology, good practices, and a low-cost-of-compliance for employers. Other rules are just bad. They are  totally out of date, not protective enough, or just not feasible/practical. Here’s my plug for a good safety manager/industrial hygienist – A good one will know which rules/guidelines to follow.

The New York Times (July 19, 2012, Cara Buckley) recently wrote an article on the US noise standards which are not protective enough for employees. In construction we also have three additional problems.

1. hearing loss is expected (or at least assumed in certain fields – carpenters, sheetmetal, ironworkers, etc.) and,
2. work shifts are usually over 8-hours. Noise exposure is usually calculated on an 8-hour time weighted average. During the busy months, an 8-hour work day is rare. It’s at least 10, maybe 12-14 hours. This doesn’t allow your ears to “rest” between shifts. For more information on extended work shifts go here.
3. extracurricular activities contribute to overall hearing loss – my point is that most construction workers don’t sit at home at the end of their shift. Almost everyone I know in construction is involved in one of these activities: hunting, shooting, motorcycles, water sports, yard work, cars, wood working/cutting, concerts, music, etc. Each of these activities contribute to their overall hearing loss, and again, doesn’t allow your ears to “rest”.

…which reminds me that I need to keep a set of ear plugs in my motorcycle jacket.

The big industrial hygiene conference (AIHCe) is held in a different city each year. This year was Indy, Indiana. Below is my personal top ten list  of “lessons learned” from last week.

1. IH’s need to do a better job of sharing. We don’t share data, experiences, information, knowledge or our ideas well.
2. CPWR is trying to share. Center for Construction Research & Training.  I’m looking forward to seeing their published independent review of local exhaust ventilation (LEV) units.
3. The minimum exhaust rate for a portable exhaust unit must be 106 cfm (cubic feet per min) to capture particulates (dust, silica) during tuckpointing with a 5 in grinder (but it’s also a good rule of thumb).
4. Asphalt milling machines are still a huge silica problem. Water controls are NOT enough. You need a local exhaust system too. (here’s an earlier post I made on it)
5. GHS Safety Data Sheets – it’s not as complicated as you think. There are some significant changes, but don’t worry, OSHA’s here to help (ha). Seriously, more information will be available soon.
6. Ignite. Have you seen these before? Short, stand up speeches about their ideas/passions. Similar to TED. Some were better than others. But, did I mention they were short?
7. Committees. Be careful when you open your mouth. My idea was so great, they are making me do it.
8.  ANSI A10.49! A health standard for construction. Great idea, but lots of work.
9. Check out Environment for Children. I don’t know much about it, but they have a great mission.  Believe me, in the US, we’re WAY ahead.
10. Presentation. It’s all up to you to make it. I will not cast blame on those who had bad presentations. BUT, it reminds me that I should work on this skill. Even if you have something good to say, if you give a horrible presentation, it’s likely no one will notice. On the other side, if your presentation is good, people will listen, even if you’re talking about nothing!  My favorite of the week: Dr. Mike Morgan (Univ. of Washington) on Chromium VI. He was very factual, not too flashy, and make the point without needless details.