Results came back above the PEL: what happens next

This page explains what the rules and common practice call for. Every site is different, and what a survey or a filing needs at your facility is something we work out with you after we see it.

When air monitoring results come back above OSHA's permissible exposure limit (PEL), four things start to happen at once, and one of them has a clock on it.

1. Notify your workers within 15 working days

Each substance-specific OSHA standard requires you to notify workers within 15 working days, in writing to each worker or by posting. Where the exposure was above the PEL, the written notice must also state that the PEL was exceeded and describe the corrective action you are taking.

Two details catch people.

The clock does not start at the same moment under every standard.

• For silica and beryllium, it runs from completing the exposure assessment.
• For hexavalent chromium, it runs from making the exposure determination.
• For lead, cadmium, benzene, formaldehyde, methylene chloride and asbestos, it runs from receipt of the results.

When the laboratory is slow, those can be quite different deadlines.

To describe the corrective action, you need a plan. A notice that says the PEL was exceeded and stops there does not satisfy the standard. You do not need the problem solved in 15 days, but you do need to be able to describe what you are doing about it.

2. Respirators, in the interim

Above the PEL, respirators are required while you put controls in place. That brings in all of OSHA's respiratory protection standard: a written program, medical evaluation, fit testing, training and cartridge change schedules.

The right respirator depends on the number you just measured. Respirator protection factors are ratios, so you need the measured exposure to know whether a half-mask is adequate or whether you need a powered or supplied-air type. This is one practical reason the air monitoring has to come before respirator selection, not after.

Respirator programs and fit testing are outside the four fields we work in.

3. The duty to control the exposure, and the order matters

The substance-specific standards require feasible engineering controls and feasible changes to how the work is run. Respirators are used while those controls are being put in place, and where the controls are not sufficient.

The order is not a suggestion. OSHA's enforcement practice expects you to show you worked down this list, known as the hierarchy of controls. So does ISO 45001, the international standard for occupational health and safety management.

1. Elimination. Stop using the material.
2. Substitution. Use a less hazardous material or process. This is often the cheapest real fix and the least considered.
3. Engineering controls. Local exhaust ventilation, enclosure, process changes, automation.
4. Changes to how the work is run. Rotation, scheduling, restricted access.
5. Personal protective equipment (PPE). Last, not first.

"We issued respirators" is not a control decision. It is the bottom of a list you have to show you worked down. Documenting why you ruled out elimination or substitution matters as much as documenting what you installed.

Detailed data is what lets you choose a control. A single overall decibel reading (dBA), or a single overall airborne concentration, tells you there is a problem but not what will fix it. For noise, that means octave band analysis, which breaks the noise down by frequency. For air, it usually means identifying which task and which source account for most of the exposure, and that depends on how the sampling is designed.

4. You must monitor again sooner, and the interval depends on the substance

There is no general rule of thumb here, and relying on one will get you in trouble. The monitoring interval depends on the substance.

Getting back under the limit does not release you right away. Most standards require consecutive results below the applicable limit before you can monitor less often or stop.

→ How often OSHA requires air monitoring, by substance

What we would tell you to do first

Do not resample right away in the hope of a better number. A second high result on the same operation, taken before anything changed, is a worse record than one. If you think the first survey caught an unrepresentative day, the answer is to document why, whether it was the production rate, a control that was down or an unusual batch. Do not roll the dice again.

Send the employee notification on time. A late notice is the easiest OSHA citation to avoid. It is also the easiest to forget while everyone is focused on the exposure itself.

Then work out the controls properly, with enough data to choose. That conversation is usually shorter than people expect, because the dominant source is often obvious once someone has measured it.