The American Lung Association website shows the results of studies which indicate that cities and towns with these very small particles have a 17% higher death rate than areas where the air is cleaner. These extremely fine particles often cannot be seen floating in the air, only when they appear after building up on surfaces like cars and furniture. Even LOW concentrations of these particles result in earlier death for those who breathe in such dirty air.
"NATURE AND SOURCES OF THE POLLUTANT
Particulate matter is the generic term used for a type of air pollution that consists of complex and varying mixtures of particles suspended in the air we breathe...
Particulate pollution comes from such diverse sources as factory and utility smokestacks, vehicle exhaust, wood burning, mining, construction activity, and agriculture.
Particles of special concern to the protection of lung health are those known as fine particles, less than 2.5 microns in diameter. (For comparison, a human hair is about 75 microns in diameter.) Fine particles are easily inhaled deeply into the lungs where they can be absorbed into the bloodstream or remain embedded for long periods of time. A recent study showed a 17% increase in mortality risk in areas with higher concentrations of small particles.
Particulate matter air pollution is especially harmful to people with lung disease such as asthma and chronic obstructive pulmonary disease (COPD), which includes chronic bronchitis and emphysema. Exposure to particulate air pollution can trigger asthma attacks and cause wheezing, coughing, and respiratory irritation in individuals with sensitive airways.
Recent research has also linked exposure to relatively low concentrations of particulate matter with premature death. Those at greatest risk are the elderly and those with pre-existing respiratory or heart disease." ("Particulate Matter," American Lung Association, September 7, 2005)
In a recent interview, one of our Save Our Canyon members spoke to Dr. Eugene Roberts, who is with the Beckman Research Institute at the City of Hope Hospital in Duarte. Doctor Roberts is a neurobiochemist, and a greatly respected researcher who studies the effects of inhaled particles (especially silica dust) on human health. His research papers are extremely detailed examinations of how the materials we inhale get into not only the lungs and air passages, but how it can actually get into the brain and central nervous system. When we inhale and smell something, we can tell if it is perfume, or apple pie, or bleach or vinegar, because very small particles of the material are absorbed into the brain as the material passes through the nasal passages right next to the brain. Then the brain reacts to those particles and remembers what that smell is.
In both the lungs and the brain, inhaled silicates cause an actual transformation of the lung or brain tissue that makes it extremely difficult for the organs to function correctly. The research Doctor Roberts has done convinces him that there is a definite connection between inhaled silica materials and Alzheimer's disease (as well as the already established links with lung cancer, emphysema, asthma, and silicosis). Doctor Roberts commended the SVT group for the work it is doing and expressed his sincere hope that we would be successful in our battle to end this pollution that is ruining our air and damaging our health.
Prolonged and repeated inhalation of respirable crystalline silica-containing dust in excess of appropriate exposure limits has caused silicosis, avlung disease. Not all individuals with silicosis will exhibit symptoms (signs) of the disease. However, silicosis can be progressive, andsymptoms can appear at any time, even years after exposure has ceased. Symptoms of silicosis may include, but are not limited to, the following:
shortness of breath; difficulty breathing with or without exertion; coughing; diminished work capacity; diminished chest expansion; reduction of lung volume; right heart enlargement and/or failure. Smoking may increase the risk of developing lung disorders, including emphysema and
lung cancer. Persons with silicosis have an increased risk of pulmonary tuberculosis infection.
Respirable dust containing newly broken silica particles has been shown to be more hazardous to animals in laboratory tests than respirable dust containing older silica particles of similar size. Respirable silica particles which had aged for sixty days or more showed less lung injury in
animals than equal exposures of respirable dust containing newly broken particles of silica.
There are reports in the literature suggesting that excessive crystalline silica exposure may be associated with adverse health effects involvingthe kidney, scleroderma (thickening of the skin caused by swelling and thickening of fibrous tissue) and other autoimmune disorders. However,
this evidence has been obtained primarily from case reports involving individuals working in high exposure situations or those who have alreadydeveloped silicosis; and therefore, this evidence does not conclusively prove a causal relationship between silica or silicosis and these adverse
health effects. Several studies of persons with silicosis also indicate an increased risk of developing lung cancer, a risk that increases with theduration of exposure. Many of these studies of silicotics do not account for lung cancer confounders, especially smoking.
Sand or gravel is not listed as a carcinogen by the International Agency for Research on Cancer (IARC), the National Toxicology Program (NTP),or the Occupational Safety and Health Administration (OSHA). In October 1996, an IARC Working Group re-assessing crystalline silica, acomponent of this product, designated respirable crystalline silica as carcinogenic (Group 1). The NTP's Report on Carcinogens, 9th edition,lists respirable crystalline silica as a "known human carcinogen." In year 2000, the American Conference of Governmental Industrial Hygienists(ACGIH) listed respirable crystalline silica (quartz) as a suspected human carcinogen (A-2). These classifications are based on sufficientevidence of carcinogenicity in certain experimental animals and on selected epidemiological studies of workers exposed to crystalline silica.
Types of Silica
Crystalline silica may be of several distinct types. Quartz, a form of silica and the most common mineral in the earth's crust, is associated with many types of rock. Other types of silica include cristobalite and tridymite.
Potential for Exposure During Construction
Concrete and masonry products contain silica sand and rock containing silica. Since these products are primary materials for construction, construction workers may be easily exposed to respirable crystalline silica during activities such as the following:
Chipping, hammering, and drilling of rock
Crushing, loading, hauling, and dumping of rock
Abrasive blasting using silica sand as the abrasive
Abrasive blasting of concrete (regardless of abrasive used)
Sawing, hammering, drilling, grinding, and chipping of concrete or masonry
Demolition of concrete and masonry structures
Dry sweeping or pressurized air blowing of concrete, rock, or sand dust
Even materials containing small amounts of crystalline silica may be hazardous if they are used in ways that produce high dust concentrations.
Health Effects of Crystalline Silica Exposure
Description of Silicosis
When workers inhale crystalline silica, the lung tissue reacts by developing fibrotic nodules and scarring around the trapped silica particles [Silicosis and Silicate Disease Committee 1988]. This fibrotic condition of the lung is called silicosis. If the nodules grow too large, breathing becomes difficult and death may result. Silicosis victims are also at high risk of developing active tuberculosis [Myers et al. 1973; Sherson and Lander 1990; Bailey et al. 1974].
A worker's lungs may react more severely to silica sand that has been freshly fractured (sawed, hammered, or treated in a way that produces airborne dust) [Vallyathan et al. 1988]. This factor may contribute to the development of acute and accelerated forms of silicosis.
Types of Silicosis
A worker may develop any of three types of silicosis, depending on the airborne concentration of crystalline silica:
Chronic silicosis, which usually occurs after 10 or more years of exposure to crystalline silica at relatively low concentrations
Accelerated silicosis, which results from exposure to high concentrations of crystalline silica and develops 5 to 10 years after the initial exposure
Acute silicosis, which occurs where exposure concentrations are the highest and can cause symptoms to develop within a few weeks to 4 or 5 years after the initial exposure [Peters 1986; Ziskind et al. 1976]
Initially, workers with silicosis may have no symptoms. As silicosis progresses, there may be difficulty in breathing and other chest symptoms such as cough. Infectious complications may cause fever, weight loss, and night sweats. Severe mycobacterial or fungal infections can complicate silicosis and may be fatal [Ziskind et al. 1976; Owens et al. 1988; Bailey et al. 1974]. Fungal or mycobacterial infections are believed to result when the lung cells (macrophages) that fight these infections are overwhelmed with silica dust and are unable to kill mycobacteria and other organisms [Allison and Hart 1968; Ng and Chan 1991]. About half of the mycobacterial infections are caused by Mycobacterium tuberculosis (TB), with the other half caused by M. kansasii and M. avium-intracellulare [Owens et al. 1988]. Nocardia and Cryptococcus may also cause infections in silicosis victims [Ziskind et al. 1976].
Medical evaluations of silicosis victims usually show the lungs to be filled with silica crystals and a protein material [Owens et al. 1988; Buechner and Ansari 1969]. Pulmonary fibrosis (fibrous tissue in the lung) may or may not develop in acute cases of silicosis, depending on the time between exposure and onset of symptoms.
Furthermore, evidence indicates that crystalline silica is a potential occupational carcinogen [NIOSH 1988; IARC 1987; DHHS 1991], and NIOSH is reviewing the data on carcinogenicity.
Silica dust is a byproduct of gravel mining, in limestone mining some strata of limestone, silica can be present as an impurity. Exposure to mine dusts containing silica can lead to
silicosis, cancer, kidney disease, chronic lung disease many years after exposure. Exposure to silica particulates in farming is a health hazard, close proximity to quarry operations is more than three times that exposure level, silica dust should be avoided.