Conducting an air emissions inventory

The need for emissions inventories has increased recently, in large part due to requirements of 1990 Clean Air Act Amendments. The essence of an emissions inventory is to locate units emitting regulated pollutants and quantify these emissions. Several methods are available for quantifying emissions: stack tests/continuous emissions monitors (CEMs); material balances; published emission factors; and engineering estimations. Once the types of information required for an inventory are known, data can be gathered, usually through plant inspections. A current map of the facility and a plant representative familiar with operations are critical. The objective is to detect all sources of air emissions, both point and fugitive. To generate a meaningful emissions inventory, the environmental manager must understand the many purposes of the inventory. A well-planned emissions inventory can be used to determine compliance with existing regulations, including state permit programs, emissions fees programs, and state-run emissions inventory requirements. An accurate emissions inventory is a critical part of a plant-wide dispersion modeling effort. Finally, the emissions inventory will enable a facility to meet requirements of the upcoming federal operating permit program.