Foundries: silica under the general industry standard, plus noise

Foundries concentrate more serious air and noise hazards in one building than almost any other kind of plant. They are also where confusing the two silica standards costs the most money.

Most silica guidance online is not written for foundries

OSHA has two silica standards, and nearly everything published about silica is written for the construction standard. Yours is the general industry standard, and the difference is real.

The construction standard has a shortcut, known as Table 1. The general industry standard does not. Table 1 lists construction tasks with specified controls and respiratory protection, and a construction employer can follow it and skip measuring exposure. The general industry standard has no table like it, neither a shorter one nor a different one.

What general industry gets is the performance option. You may use air monitoring results, objective data, or any combination of the two, provided the data is good enough to show accurately what workers are breathing. That path is built on data, not on a task recipe, so you have to have the data.

Plant managers read construction guidance, install the controls it describes and conclude they are finished. They still have to determine how much silica their workers are breathing.

→ Respirable crystalline silica air monitoring for general industry

Where the exposures actually are

Shakeout and finishing usually have the highest silica exposures in the building. They are often sampled as one similar exposure group with pouring, and they should not be. The task is different, the state of the material is different, and the time spent on the task is different.

The rest of the picture:

• Sand handling, mulling and core making. Silica, plus binder systems. Phenolic urethane cores bring methylene bisphenyl isocyanate (MDI), which has to be collected on a specially treated filter.
• Melting and pouring. Metal fume, carbon monoxide and heat.
• Grinding and cutting. Silica, metal dust and the highest noise levels in most foundries.
• Welding and repair. Manganese, and hexavalent chromium on high-alloy work.
• Heat stress. A real hazard with no OSHA standard of its own, so it falls under the General Duty Clause. Heat stress surveys are outside the four fields we work in.

Noise, and why a single overall decibel reading is not enough

Foundry noise comes mostly from a few sources: shakeout, grinding, air tools and compressed air. That makes octave band analysis, which breaks the noise down by frequency from low to high, worth the effort. It usually identifies a control that a single decibel (dBA) reading cannot.

Two rooms can both read 95 decibels and need completely different controls that will not work for each other. One has a low-frequency rumble that calls for mass and isolation, while the other has high-frequency air noise that a nozzle change costing a few hundred dollars will fix. Selecting controls from one overall decibel reading is how noise control budgets get wasted.

→ Noise surveys · Octave band analysis

The TRI reporting side

Foundries often cross the reporting thresholds for metals: manganese, chromium, nickel, copper, zinc and lead. The report in question is the Toxics Release Inventory (TRI), EPA's annual report on toxic chemical releases.

Metal compound categories work differently from ordinary listed chemicals. The threshold applies to the total for the whole category, while releases are reported on the weight of the parent metal.

Arizona foundries that file a Form R, the full TRI report, also owe the state a Toxic Data Report on the same July 1, and they must prepare a state pollution prevention plan.

→ How we handle Form R and TRI reporting

What we do for foundries

An air monitoring survey measures what your workers are breathing, and a noise survey measures the noise exposure of each job. For Form R, we make the threshold determination, run the calculations and file the report.