Quantification of plume opacity by digital photography

Area of Science:

• Environmental science
• Air quality monitoring
• Industrial emissions

Background:

• The United States Environmental Protection Agency (USEPA) Method 9 relies on human observation for plume opacity quantification.
• Human observation is subjective and costly due to mandatory observer recertification.
• There is a need for a more objective and cost-effective method for measuring plume opacity.

Purpose of the Study:

• To introduce and evaluate the Digital Opacity Method (DOM) as an alternative to the USEPA Method 9.
• To assess DOM's objectivity, cost-effectiveness, and digital record-keeping capabilities.
• To validate DOM's accuracy against established error limits.

Main Methods:

• Developed the Digital Opacity Method (DOM) utilizing calibrated digital photography.
• Interpreted pixel values from photographs using contrast and transmission models.
• Quantified plume opacity based on pixel data related to plume-background contrast and radiance.

Main Results:

• DOM was field tested using a smoke generator.
• The method demonstrated improved objectivity and provided a digital record.
• DOM's individual and average opacity errors were within the acceptable limits of USEPA Method 9.

Conclusions:

• The Digital Opacity Method (DOM) shows significant promise as a viable alternative to USEPA Method 9.
• DOM offers a more objective, lower-cost approach to plume opacity measurement.
• The method's accuracy supports its adoption for air quality monitoring.