Airborne contamination

Chapter 2 - ENVIRONMENTAL PROTECTION

CLASSIFICATION OF ENVIRONMENT CONTAMINATION

Pollution of environment: entry of potentially dangerous components which destroy or reduce productivity of ecosystem.

Pollution is classified as natural and anthropogenic.

Natural pollution is caused by disasters (volcano eruption, mud and stone flow). Its rating doesn’t change significantly.

Anthropogenic pollution is localized near people activity and has stable spots of high concentration pollutants. It can be mechanical, physical, chemical and biological.

Mechanical pollution: with agents which can’t have physical or chemical reactions.

Physical pollution is divided into thermal (that changes temperature), light (that changes natural illumination, what in turn changes tempo of plants and animals), electromagnetic (that causes changes in biological tissues), radiation (that has ionizing effect).

Chemical pollution changes average concentration of any substance or entry of substances which had been naturally absent.

Biological pollution is appearing of extremely amount of microorganisms.

An airborne contaminant is a potentially harmful substance that is either naturally absent from air or is present in an unnaturally high concentration, and to which people may be exposed in their environment.

The uptake of airborne contaminants occurs throughout the respiratory system, digestive organs, skin and mucous membrane.

The dominant driving force in the uptake of gases, vapors and dust is in respiratory system, liquid substances – through the skin. Contaminants get into alimentary tract while swallowing due to dirty hands.

CLASSIFYING HAZARDOUS SUBSTANCES:

1. toxic – substances which cause acute lethal effects, irreversible health effects such as damage to the central nervous system, kidneys or liver, or which cause anemia or paralysis after a single dose, may be classified as very toxic, toxic or harmful (carbon monoxide, lead, mercury);

2. irritant – a substance that causes inflammation of the skin, eye irritation, serious eye problems or irritation to the respiratory system (chlorine, acetone, ozone, formaldehyde, phosgene and nitrogen oxides, sulphur oxides;.

3. sensitizer – a substance that causes a substantial proportion of people exposed to develop an allergic reaction after repeated exposure to the substance (formaldehyde: used as formalin and in the manufacture of synthetic resin, various lacquers, solvents);

4. carcinogenic – any substance that produces cancer (nickel and its compounds, asbestos, chrome oxide);

5. mutagenic – a substance or agent that can induce genetic mutation (lead, manganese, radioactive substances);

6. teratogenic – any substance that causes malformations in a fetus (mercury, lead, manganese, radioactive substances).

Dusts are solid particles generated and dispersed into the air by, for example, handling, crushing and grinding of organic or inorganic materials such as rock, ore, metal, coal, wood and grain.

The health effects caused by particulate exposure are equally diverse.

Skin contact with some dusts, such as organic dusts from flour and grains, may cause irritation or allergic responses in sensitized persons, while inhalation of other organic dusts, particularly some wood dusts, has been shown to cause nasal cancer in heavily exposed workers. However, the major health effects are usually found in the lungs

The mixture of dust and air makes dispersion, where air is dispersion media and dust is dispersed fraction.

Dispersion classifies dusts by particle size:

- inhalable dust has a 50% cut-point of 100 microns (10 < d £ 100 microns);

- thoracic dust has a 50% cut-point of 10 microns (5 < d £ 10 microns);

- respirable (smoke) dust has a 50% cut-point of 5 microns (d £ 5 microns); that dust is so small in size that it can get through the lung defense mechanisms of the human body and get down deep into the gas exchange (alveolar) region of the lung.

Known biological effects:

- silicosis, which results from exposure to silica;

- other lung reactions include bronchitis – inflammation of the bronchi;

- asthma, which is a constriction of the bronchial tubes; and

- cancer;

- restricted lung function can place burden on the right side of the heart and this additional stress can result in irreversible heart damage over time.

Дата добавления: 2014-01-04