Glossary of Terms: R

Radiation
The energy transmitted by waves through space or some medium. There are two types of radiation: ionizing (for example, X-Rays or radiation from a radioactive device), and non-ionizing radiation (for example, infra-red radiation, ultra- violet radiation).
Random incidence
A Class/Type 1 microphone. Measurements made in an area where sound waves are coming from all directions, including reflections and diffractions. When the dosimeter is being used as a sound level meter in an area where reflections and diffractions from nearby objects are present, use the Random Incidence Corrector with the microphone, and angle the microphone at approximately 70 degrees. Most personal noise dosimetry applications do not require the random incidence corrector, since they are not measured with a Class/Type 1 microphone.
RCRA
Resource Conservation and Recovery Act of 1976. (US Environmental Protection Agency)
Reactivity
The capability of a substance to undergo a chemical reaction with the release of energy. Unwanted effects include pressure build-up, temperature increase, and formation of harmful by-products. These effects may occur because of the reactivity of a substance to heat, an ignition source, or direct contact with other chemicals in use or in storage.
Reducing agent
A substance that accepts oxygen or gives up hydrogen during a chemical reaction. Oxidation and reduction always occur at the same time. See oxidizing agent.
Reference pressure
The sound pressure at the threshold of human hearing, as measured under standard conditions. The generally accepted magnitude of this pressure is 2 × 10 5 Pascals (Pa).
Relative humidity
the ratio of the amount of water in the air at a specific temperature to the maximum capacity of the air at that temperature
RELs
Recommended Exposure Levels (NIOSH).
Repetitive strain injury (RSI)
A problem with the muscles, tendons or nerves that happens over time due to overuse. Examples of repetitive strain injuries include carpal tunnel syndrome and tendonitis.
Reproductive hazards
Any material that can affect the development of sperm and egg cells. This can lead to an inability to have children, birth defects and other harmful changes.
Respirable particles
Small particles that can be breathed in and reach parts of the respiratory system where they may have a harmful effect (for example, the lungs).
Respirable size particulates
Particulates in the size range that permits them to penetrate deep into the lungs upon inhalation. Materials <10µ can penetrate to the lungs when inhaled and can be hazardous
Respirator (approved)
A device which has met the requirements of 30 CFR Part 11 and is designed to protect the wearer from inhalation of harmful atmospheres and has been approved by the National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA).
Respiratory system
Consists of (in descending order) - the nose, mouth, nasal passages, nasal pharynx, pharynx, larynx, trachea, bronchi, bronchioles, air sacs (alveoli) of the lungs, and muscles of respiration.
Response curve
The line that shows detector response to gas at points over time.
Response time
The response determines how quickly the unit responds to fluctuating noise. Fast has a time constant of 125 milliseconds. Slow has a time constant of 1 second.
RFI
Radio Frequency Interference.
RH
Relative Humidity.
Risk
The probability of a worker suffering an injury or health problem, or of damage occurring to property or the environment as a result of exposure to or contact with a hazard.
Root cause
The real or underlying cause(s) of an event. Distinguished from immediate cause(s) which are usually quite apparent.
Root mean square (RMS)
Value resulting from a dosimeter with the response time and weighting settings taken into account. RMS voltage of a signal is computed by squaring the instantaneous voltage, integrating over the desired time, and taking the square root.
Route of entry
The method by which a contaminant can enter the body. There are four main routes of entry. Contaminants can be breathed in (inhalation), swallowed (ingestion), absorbed through the skin, or injected into the bloodstream.
RS485/232/422
Digital communication protocols.