Particles health effects

Finally, particulate matter (PM), or the solid and liquid particles that are released into the atmosphere, comes from both the actual emissions of particulates and the reaction between atmospheric molecules and SO2 or NO. Particulate matter can be divided based on the size of the particle. Health effects include respiratory distress as well as cancer and permanent lung damage. Fine particulate matter (<2.5 microns in size, PM 2.5) is a major cause of reduced visibility, or haze, in many parts of the country. The EPA notes visibility in several of our nation s national parks and wilderness areas has been negatively affected by high particulate levels in the air. Particulate emissions that are not the result of other pollutants or natural causes come primarily from the industrial sector (EPA 1995). 

Aerosol Dynamics. Inclusion of a description of aerosol dynamics within air quaUty models is of primary importance because of the health effects associated with fine particles in the atmosphere, visibiUty deterioration, and the acid deposition problem. Aerosol dynamics differ markedly from gaseous pollutant dynamics in that particles come in a continuous distribution of sizes and can coagulate, evaporate, grow in size by condensation, be formed by nucleation, or be deposited by sedimentation. Furthermore, the species mass concentration alone does not fliUy characterize the aerosol. The particle size distribution, which changes as a function of time, and size-dependent composition determine the fate of particulate air pollutants and their... 

The particles most likely to cause adverse health effects are the fine particulates, in particular, particles smaller than 10 p and 2.5 mm in aerodynamic diameter, respectively. They are sampled using (a) a high-volume sampler with a size-selective inlet using a quartz filter or (b) a dichotomous sampler that operates at a slower flow rate, separating on a Teflon filter particles smaller than 2.5 mm and sizes between 2.5 mm and 10 mm. No generally accepted conversion method exists between TSP and PM,o, which may constitute between 40% and 70% of TSP. In 1987, the USEPA switched its air quality standards from TSP to PMk,. PM,q standards have also been adopted in, for example, Brazil, Japan, and the Philippines. In light of the emerging evidence on the health impacts of fine particulates, the USEPA has proposed that U.S. ambient standards for airborne particulates be defined in terms of fine particulate matter. 

Health effects attributed to sulfur oxides are likely due to exposure to sulfur dioxide, sulfate aerosols, and sulfur dioxide adsorbed onto particulate matter. Alone, sulfur dioxide will dissolve in the watery fluids of the upper respiratory system and be absorbed into the bloodstream. Sulfur dioxide reacts with other substances in the atmosphere to form sulfate aerosols. Since most sulfate aerosols are part of PMj 5, they may have an important role in the health impacts associated with fine particulates. However, sulfate aerosols can be transported long distances through the atmosphere before deposition actually occurs. Average sulfate aerosol concentrations are about 40% of average fine particulate levels in regions where fuels with high sulfur content are commonly used. Sulfur dioxide adsorbed on particles can be carried deep into the pulmonary system. Therefore, reducing concentrations of particulate matter may also reduce the health impacts of sulfur dioxide. Acid aerosols affect respiratory and sensory functions. 

NUCRAC improves on the health effects model by a reexamination of Hiroshima and Nagasaki data. The dry deposition model was much improved by the inclusion of a particle-si/e distribution, a detailed settling model, and a detailed chronic exposure model via the food pathway. However, it does not include a rainout model. 

Interest in the elemental composition of aerosol particles arises from concerns about health effects and the value of these elements to trace the sources of suspended particles. The following physical analysis methods have been applied for the elemental measurements of aerosol samples. A schematic drawing of an x-ray fluorescence system is presented in Fig. 13.42. 

Acid deposition and the associated particulate nitrates and sulfates are implicated in the deterioration of certain sensitive ecosystems, decreased visibility, negative human health effects, and increased degradation of certain stone building materials and cultural resources, especially those made of limestone and marble. Fine particulate nitrate and sulfate particles... 

Since these PM standards were established, the EPA has reviewed peer-reviewed scientific studies that suggest that significant health effects occur at concentrations below the 1987 standards. In addition, some studies attributed adverse health effects to particles smaller than 10 microns. In July 1997, the EPA, under the National Ambient Air Quality Standards (NAAQS), added standards for particulate matter with a diameter of 2.5 microns or less (PM, ). The annual PM, 5 standard was set at 15 pg/ni and the 24-hour PMj standard was set at 65 p.g/m . 

Aerosol spray cans were invented in 1929, and perfection of a reliable valve and development of disposable cans took place in the 1940s. Shortly thereafter, aerosol became a household word. Like many other modem conveniences, however, the aerosol spray can has drawbacks as well as advantages. Because the particles in an aerosol are extremely tiny, they are quite mobile. They last for a long time in the atmosphere and can affect the climate, as already described. They can penetrate deep into our lungs and cause adverse health effects. Thus, anthropogenic aerosols have both global and local side effects. Despite increasing scientific studies, these effects are not yet fttlly understood. 

The radiation from exposure to americium is the primary cause of adverse health effects from absorbed americium. Upon entering the body by any route of exposure, americium moves relatively rapidly through the body and is concentrated in bones where it remains for a long time. While in the bone, americium atoms decay, releasing alpha particles and gamma-rays. Alpha... 

The second emission U.S. EPA regulates is PM. PM consists of small dust-like particles emitted from BIFs. Although the particles themselves may cause adverse health effects (e.g., increased asthma), they also provide a point of attachment for toxic metals and organic compounds. The particulates may become caught in the lungs or be absorbed into the environment. To minimize these adverse conditions, U.S. EPA set an emission limit of 180mg/dscm. BIFs that qualify for the low-risk waste exemption mentioned above, however, are not subject to the PM standard.5... 

Oberdorster, G. et al. (2005) Principles for characterizing the potential human health effects from exposure to nanomaterials elements of a screening strategy. Particle and Fibre Toxicology, 2 (1), 8. 

Plastic products are known to eventually break down into smaller and smaller pieces (nanoparticles) until they are small enough to enter the cells of living organisms. Because the amount of discarded plastic is so substantial, nanoplastic particles pose an emerging environmental concern. The health effects of nanoplastics are not thoroughly understood, but polystyrene particles up to 240 nm in diameter have been proven to be transportable through placental cells [52],... 

Here we have only discussed the concentration of the radon gas. This is because the measurements have been made of this nuclide. However, the health effects are referred to the short-lived decay products. The equilibrium factor depends on the ventilation rate and the particle concentrations. 

National Academy of Sciences-National Research Council, Health Effects of Alpha-Emitting Particles in the Respiratory Tract, Report of AD Hoc Committee on Hot Particles, U. S. Environmental Protection Agency, EPA 520/4-76-013, October 1976. 

Another concept relating to the decay products is that of the "unattached" fraction. Although it is now known that the decay product atoms are really attached rapidly to ultrafine particles (0.5 to 3 nm in diameter), there is a long history of an operationally defined quantity called the "unattached" fraction. These decay products have much higher mobilities in the air and can more effectively deposit in the respiratory system. Thus, for a long time the "unattached" fraction has been given extra importance in estimating the health effects of radon decay products. Typically most of the "unattached" activity is Po-218 and the value of unattached frac-... 

Indoor radon in most houses come primarily from soil gas infiltrating into the house because of pressure-driven flow. The radon decays into a series of decay products to which most of the health effects are attributed. These decay products begin attached to ultrafine particles that either plateout on surfaces such as walls, furniture, etc., or become attached to larger particles that are present in the indoor air. The nature of those particles depends on the kinds of sources that exist in the house such as smokers, gas stoves, etc. 

Particulate matter (PM) is associated with adverse human respiratory health effects. Although much research has focused on the fine particle component (PM2.5), recent results from the USC Children s Health Study suggest that the coarse fraction may also affect respiratory health in children. Specific components of the coarse fraction responsible for these effects have not been identified, but ambient endotoxin is a strong candidate, based on toxicologic and epidemiologic studies. This study is collecting... 

The effects of transport on economy, people and on the environment are manifold. They include the consequences of transport accidents and fatalities, nuisance and health effects caused by steady noise exposure, air emissions and the exhaust and resuspension of particles, climate impacts by the emission of greenhouse gases, soil and water contamination, and the deterioration of natural habitats. Moreover, the financial burden of infrastructure provision and the additional travel and production costs caused by congestion should be mentioned but these items are mainly borne by transport users themselves and thus are only partly imposed on society as a whole. Not all of these effects are equally relevant for all means of transport. While accidents constitute the major problem of car travel, the railways definitely face a noise problem and air transport contributes most to the emission of climate gases. 

Radioactivity results when some part of an atom is unstable. The instability exists because the orbital electrons or the nucleus contain too much energy. Radioactive atoms are called radionuclides. They release excess energy by emitting radiation. The type of radiation released (alpha, beta, or gamma particles) may be more or less hazardous to humans, depending on the location of the radioactive materials. Exposure to radioactive materials outside the body poses external hazards. Radioactive materials may also be hazardous when ingested, inhaled, or injected and thus pose internal hazards. The sections below describe the characteristics of radiation particles as external or internal hazards and as they may be encountered after a terrorist attack. Chapter 3 provides additional details and addresses health effects associated with exposure to radiation. 

Radioactive substances (radionuclides) are known health hazards that emit energetic waves and/or particles that can cause both carcinogenic and noncarcinogenic health effects. Radionuclides pose unique threats to source water supplies and chemical processing, storage, or distribution systems because radiation emitted from radionuclides in chemical or industrial waste systems can affect individuals through several pathways by direct contact with, ingestion or inhalation of, or external exposure to, the contaminated waste stream. While radiation can occur naturally in some cases due to the decay of some minerals, intentional and nonintentional releases of... 

The assessment of health effects due to exposure to the total petroleum hydrocarbons requires much more detailed information than what is provided by a single total petroleum hydrocarbon value. More detailed physical and chemical properties and analytical information on the total petroleum hydrocarbons fraction and its components are required. Indeed, a critical aspect of assessing the toxic effects of the total petroleum hydrocarbons is the measurement of the compounds, and the first task is to appreciate the origin of the various fractions (compounds) of the total petroleum hydrocarbons. Transport fractions are determined by several chemical and physical properties (i.e., solubility, vapor pressure, and propensity to bind with soil and organic particles). These properties are the basis of measures of teachability and volatility of individual hydrocarbons and transport fractions (Chapters 8, 9, and 10). 

The health effects of particulate matter (a complex mixture of solids and liquids) emissions are not yet well understood but are recognized as major contributors to health problems. Biological activity of particulate matter may be related to particle sizes and/or particle composition. Furthermore, it has generally been concluded that exposure to particulate matter may cause increased morbidity and mortality, such as from cardiovascular disease. Long-term exposure to particulate emissions is also associated with a small increase in the relative risk of lung cancer. 

PM causes its health effects, especially its effect on cardiovascular health, are unclear there is some evidence that chemical composition of PM is not as important as particle size, with the greatest risks associated with what is designated as PM 2.5 (particle size less than 2.5 pm). Some experimental evidence suggests (but does not establish) that so-called fine (0.25 to 1.0 pm) and ultrafine (<0.25 pm) are the most potent toxicants, but regulation is now focused on PM 2.5. Regulation of PM and the primary air pollutants is highly contentious, because the costs of controlling them are enormous. 

During controlled exposures of human subjects to specific compounds like ozone, the concentrations of suspended particles and trace gases must be known and minimized to ensure that health effects can be attributed solely to ozone. The air purification units for the environmental chambers are designed to remove most of the particles and pollutant gases from the ambient air. Prefilters and efficient absolute filters are used to remove 99% of the particles with diameters of 0.3 nin... 

No adverse health effects were observed in male rats exposed by inhalation to 3,3 -dichlorobenzidine free base (23,700 mg/m ) 2 hours per day for 7 days (Gerarde and Gerarde 1974). In another study, 10 rats were exposed to an unspecified concentration of 3,3 -dichlorobenzidine dihydrochloride dust particles for 1 hour and then observed for 14 days. Slight-to-moderate pulmonary congestion and one pulmonary abscess were observed upon necropsy (Gerarde and Gerarde 1974). The effects observed in the study using the ionized (hydroehloride) form of 3,3 -dichlorobenzidine may have been due to the irritative properties of hydrochlorie aeid released from the salt in combination with particulate toxicity. 

EPA. 1990f. Unvented kerosene heater emissions from mobile homes Studies on indoor air particles, semi-volatile organics, carbon monoxide, and mutagenicity. Research Triangle Park, NC U.S. Environmental Protection Agency, Health Effects Research Laboratory. Report no. EPA/600/D-90/122. 

The results presented here suggest a new mechanism of toxicity for PM 5 based on sustained hydroxyl radical generation by the semiquinone radicals present in PM 5. Because a substantial fraction of the fine particles in the atmosphere arises from combustion sources (9), it is possible that the deleterious health effects associated with PM2 5 can be at least partially ascribed to radicals associated with combustion-generated particulate matter. 

These pathways are thought to result in the production of superoxide (13) or in the release of superoxide directly from the particles themselves. Superoxide production leads to the formation of hydrogen peroxide, and metal ions such as Fe + react with hydrogen peroxide to produce the hydroxyl radical. It is well documented that the hydroxyl radical can damage DNA as well as lipids and proteins (18, 19). Some of the health effects of cigarette tar and smoke are attributed to free radicals that can initiate production of superoxide and hydroxyl radical (3, 10, 11, 20, 21). (Adapted from Dellinger et al., 2001)... 

Move 1] Currently atmospheric particulate matter is regulated based on various size categories because of the apparent association between particle size and adverse health effects. [Move 2] However, the current size-based understanding of atmospheric particles is relatively crude because it does not account for differences in the chemical composition of these particles. Presumably a chemically reactive particle has a greater potential for damage than a chemically inert particle of comparable size. Of the metals potentially... 

Evidence of the relatively benign nature of aluminum dust in measured concentrations lies in the 27-year experience of administration of freshly milled metal particles to workers exposed to silica as a suggested means of inhibiting the development of silicosis. Inhalation of aluminum powder of particle size of 1.2 p, (96%), over 10- or 20-minute periods several times weekly, resulted in no adverse health effects among thousands of workers over several years. 

Commercial carbon black is a spherical colloidal form of nearly pure carbon particles and aggregates with trace amounts of organic impurities adsorbed on the surface. Potential health effects usually are attributed to these impurities rather than to the carbon itself. Soots, by contrast, contain mixmres of particulate carbon, resins, tars, and so on, in a nonadsorbed state. ... 

Krewski D, et al Reanalysis of the Harvard Six Cities study and the American Cancer Society Study of Particulate Air Pollution and Mortality A Special Report of the Institute s Particle Epidemiology Reanalysis Project. Cambridge, AlA Health Effects Institute, 2000... 

---