Emissions, tonnage

Compliance with regulations and internal standards. These requirements usually cover emissions tonnage or concentrations, workplace exposure levels and progress in correcting noncompliances. 

Air Pb levels in the 20-year interval from 1983 to 2002 declined by 94% in U.S. urban and suburban areas, with emission tonnages corresponding to these figures declining from 220,000 tons in 1970 to <4,000 tons in 1999 (U.S. EPA, 2006). However, the previous decades of airborne Pb emissions created an enormous terrestrial reservoir of the element that could be reentrained as fugitive dusts at smelter sites and along countless U.S. roadways. Furthermore, stationary sources such as smelters, foundries, and incinerators noted in earlier chapters were emitting discernible levels. 

Tonnage of air emissions, water emissions and liquid and solid effluent and tonnage of hazardous materials released into the environment. These two measures are related to one another. However, the first measure relates the total effluent, including nonpolluting materials. The second measure looks only at the tonnage of hazardous materials contained in the total effluent. Both measures can be important indicators. For example, for solid waste it is important to know the total volume of material for disposal and different upstream treatment techniques may affect the total volume. However, for ozone depleting chemicals, only the quantity of these gases is important and other components such as water vapor may be irrelevant. 

Emissions to water discharges from the 35 French sites are presented as a UIC (Union des Industries Chemiques) water index. Since 1988 this index has fallen 40% to a value of 20 (1% less than the 1997 figure). Tonnage discharges given below are figures for the whole group of 61 sites ... 

Emissions to land the total tonnage of hazardous waste shipped from Hickson s sites has increased from 9306 tonnes in 1994 to 22 488 tonnes in 1998. During the same period the quantity shipped per tonne of saleable product has increased from 0.114 to 0.179 tonnes. Hickson state that this does not mean that we are generating larger amounts of waste. It is because the regulations have changed over the same period of time to include more materials as hazardous. ... 

In many countries, well over half of the tonnage of screened grades of limestone is delivered from the quarry to local users by tipper truck. Tliis option has the advantage of being relatively cheap and very flexible. Control of dust emission during transportation is achieved by sheeting the load. 

The basic advantages of a conventional batch plant, which is usually stationary, are the following flexibility to produce all types of asphalts, small tonnages are possible to be produced, high percentage of reclaimed asphalt can be added, storage of mixed asphalt is not essential and emissions are within acceptable limits. 

Lead emission rates in terms of annualized tonnages are described here for mainly contemporary industrialized/industrializing societies emission rates. Data for earlier centuries or millennia are not available. Investigators examining such matters instead are confined to comparative contamination chronologies to evaluate current levels of media-specific Pb and relative changes in these concentrations over time as discerned from media that reflect such changes. Levels of lead in environmental media that contribute to current human exposures are the main subject of Chapter 6. 

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