AIR QUALITY TESTING AND MONITORING METHODS OF SAMPLING

Indoor air quality testing may be necessary to ensure employee safety. Testing and monitoring may be applied to those conditions where employees may be exposed to:

nitrogen dioxide and sulfur dioxide
landfill gases
noxious odors
radon gas
factory emissions
odor complaints
rainwater
metals
smoke levels
dust
volatile organic compounds
indoor air quality (including Carbon Monoxide)

The results of air quality testing may be used to:
• Assign levels of worker respiratory protection
• For emergency planning

Methods of Sampling and Testing
Electric Power producers shall provide adequate means of carrying air monitoring in generator houses, transmitting stations, injection and switching substations, etc.

Three main methods are available to measure air pollution:

Passive Sampling: This refers to absorption or diffusion tubes or badges that provide a simple and inexpensive indication of average pollution levels over a period of weeks or months. Plastic tubes or discs open at one end to the atmosphere and with a chemical absorbent at the other, collect a sample for subsequent analysis in the laboratory.

The low cost per tube allows sampling at a number of points and is useful in highlighting "hotspots" where more detailed study may be needed. The quality and accuracy of the data from passive sampling tubes does not make them suitable for precise measurements but they can give useful long term trend data.

Active Sampling: This involves the collection of samples, by physical or chemical means, for subsequent laboratory analysis. Typically, a known volume of air is pumped through a filter or chemical collector for a known period of time - the collection medium is then subjected to laboratory analysis. This method is not suitable for continuous or near-real time air quality monitoring.

Automatic Sampling: This is the most sophisticated method of air quality analysis, producing high-resolution measurement data of a range of pollutants. The pollutants that can be measured include, but are not limited to, NOx, S02 CO, 03, VOCs, PM10, PM2.5, Carbon Black, Hg, Benzene etc. The air quality is continuously sampled and measured on-line and in real-time.

The real time data is stored, typically as one hourly averages, with data being collected remotely from individual monitoring stations by telemetry. Remote control of the monitoring and data system is also possible as is remote diagnostics for most of the analyzers.