Developing a Framework for Effective Air Quality Management
3.5 Understanding the Sources of Air Quality Problems
3.5.4 Emission Inventory Changes Over Time
Clearly, an emission inventory can represent only a point in time. The maxim that “the only thing that is constant is change” is certainly true with respect to an emissions inventory. Emissions are not even consistent throughout the day or the year. To address this problem, regions develop summer and winter inventories or even quarterly inventories. For modeling purposes inventories are often divided by the hour of the day.
The starting inventory for an air quality management plan is often referred to as the “base” inventory for the region. It is then necessary to estimate how emissions will change into the future without intervention in order to develop appropriate air pollution control measures. It is normal to project inventories at one to five-year intervals. The inventories are projected at least up to the year when attainment for the region is expected. However, it is valuable to create inventories for periods beyond compliance dates to ensure maintenance of air quality levels. To make projections, the inventory technician must rely upon population projections, industrial growth projections, transportation projections and the like to make these future projections.
The projection of inventories into the future requires an understanding of the growth expected in the near and long term future of the region. This includes not only the population growth, growth in energy demands and vehicle travel, but also the economic growth plans, the energy infrastructure goals of the government, and other trends of the region in consideration. A properly devised plan will build upon the opportunities as they develop and maximize co-benefits that build upon the direction already in place.
Once the potential sources of an air quality problem in a region are identified, then these sources are normally cataloged into a database that can be used for many purposes if well designed. It is with the aid of an emissions inventory that the most cost effective control measures are studied and selected, that air quality modeling is carried out, and that air quality trends are evaluated.
The starting inventory for an air quality management plan is often referred to as the “base” inventory for the region. It is then necessary to estimate how emissions will change into the future without intervention in order to develop appropriate air pollution control measures. It is normal to project inventories at one to five-year intervals. The inventories are projected at least up to the year when attainment for the region is expected. However, it is valuable to create inventories for periods beyond compliance dates to ensure maintenance of air quality levels. To make projections, the inventory technician must rely upon population projections, industrial growth projections, transportation projections and the like to make these future projections.
The projection of inventories into the future requires an understanding of the growth expected in the near and long term future of the region. This includes not only the population growth, growth in energy demands and vehicle travel, but also the economic growth plans, the energy infrastructure goals of the government, and other trends of the region in consideration. A properly devised plan will build upon the opportunities as they develop and maximize co-benefits that build upon the direction already in place.
Once the potential sources of an air quality problem in a region are identified, then these sources are normally cataloged into a database that can be used for many purposes if well designed. It is with the aid of an emissions inventory that the most cost effective control measures are studied and selected, that air quality modeling is carried out, and that air quality trends are evaluated.
