The AQMD is the local government agency
responsible for air quality assessment in
In order to attain healthful air, federal and state laws require the AQMD to adopt an Air Quality Management Plan (AQMP) that identifies control strategies to demonstrate compliance with federal ambient air quality standards and expeditious progress toward state air quality standards (1) To address these state and federal mandates, the 2003 AQMP for the Basin included Control Measure BCM-08 – Further Emission Reductions from Aggregate and Cement Manufacturing Operations, which identified aggregate and cement operations as sources of PM10 emissions. As such, Control Measure BCM-08 calls for the development of controls to reduce the emissions from these industries. Proposed Rule 1157 – PM10 Emission Reductions from Aggregate and Related Operations, is developed to implement a portion of Control Measure BCM-08. Subsequently, a separate rule will be proposed to address emissions generated by cement manufacturing operations.
Aggregate (including stone crushing) and related operations, such as hot-mix asphalt, concrete batching, miscellaneous base crushing, concrete product plants, landfills handling construction and demolition debris, as well as facilities handling/using cement and aggregates are sources of direct PM10 emissions.
PM10 is generated during the mining, processing, and handling (i.e., transporting, loading/unloading, conveying, crushing, screening, mixing, and storing) of the aggregates. Other sources of PM and PM10 emissions are unpaved roads and track-out (where PM dust generated by the facility is transported due to out-going truck traffic to part of the public roads.)
PM10 is a public health concern since particles of less than 10 microns in size can be deposited in, and can damage the airways of the lower respiratory tract and the gas-exchange portions of the lung. The adverse health effects of particulates, especially PM10, are well documented. Various health studies have linked PM10 emissions to increased respiratory infections, more severe asthma, declines in pulmonary function, and shortened life spans. Current ambient levels of PM10 (30 to 150 micrograms per cubic meter) are associated with increases in the number of people that die daily from heart or lung failure. Most of these deaths are common among the elderly. However, there is strong evidence that some children are also adversely affected by PM10 emissions. The USC Children’s Health Study suggests that children with asthma living in a community with high PM10 concentrations may have suppressed lung growth. After the children moved into cleaner cities, their lung growth returned to the normal rate, but they did not recover the lost potential growth, according to John Peters, the study’s principle investigator.
Increases in ambient PM10 levels have also been shown to result in increases in acute respiratory hospital admissions, school absences in children, and increases in the use of medications in children and adults with asthma. The American Thoracic Society’s Environmental and Occupational Health Assembly reviewed current health effects literature. They report that daily fluctuations in PM10 levels have been related to: acute respiratory hospital admissions in children; school and kindergarten absences; decreases in peak lung air flow rates in normal children; and, increased medication use in children and adults with asthma.
Silica Dust
Silica dust is
generated during the surface mining, processing, and handling (i.e.,
transporting, loading/unloading, conveying, crushing, screening, mixing, and
bagging) of the aggregates. Elevated
silica dust levels are frequently found
in granite quarrying and processing, in crushed stone and related
industries. Currently OSHA (Occupational
Safety and Health Administration) has established permissive exposure limit
(PEL) of 0.1 mg/m3 for this type of operations.
Studies
indicate that exposure to silica dust over a long period of time causes
Silicosis. Silicosis (especially the
acute form) is characterized by shortness of breath, fever, bluish skin, and
may often be misdiagnosed as pneumonia or tuberculosis. Silicosis may be fatal when the lung
scavenger cells are overwhelmed with silica dust and are unable to kill
mycobacterium and other organisms.
Studies of granite quarry workers also establish the link between human
lung cancer and exposure to silica dust.