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Air pollution is the presence of substances in the atmosphere that are harmful to humans and other living beings, or cause damage to the environment. Air pollution can be chemical, physical or biological. [1]
Highly toxic to humans in its elemental form. [11] iridium: 77: 1a: Due to its extreme rarity, iridium has no biological role. [11] The chloride is moderately toxic to humans. [11] iron: 26: 5: Essential to almost all living things, usually as a ligand in a protein; it is most familiar as an essential element in the protein hemoglobin. [11 ...
Many gases have toxic properties, which are often assessed using the LC 50 (median lethal concentration) measure. In the United States, many of these gases have been assigned an NFPA 704 health rating of 4 (may be fatal) or 3 (may cause serious or permanent injury), and/or exposure limits (TLV, TWA/PEL, STEL, or REL) determined by the ACGIH professional association.
Though elemental sulfur is only minimally absorbed through the skin and is of low toxicity to humans, inhalation of sulfur dust or contact with eyes or skin may cause irritation. Excessive ingestion of sulfur can cause a burning sensation or diarrhea, [ 136 ] and cases of life-threatening metabolic acidosis have been reported after patients ...
Sulfur dioxide is somewhat toxic to humans, although only when inhaled in relatively large quantities for a period of several minutes or more. It was known to medieval alchemists as "volatile spirit of sulfur".
Volcanic gases include carbon dioxide, which can be fatal in large concentrations and contributes to climate change, hydrogen halides which can cause acid rain, sulfur dioxides, which are harmful to animals and damage the ozone layer, and hydrogen sulfides, which are capable of killing humans at concentrations of less than 1 part per thousand. [20]
Many metals, particularly heavy metals are toxic, but some are essential, and some, such as bismuth, have a low toxicity. Metals in an oxidation state abnormal to the body may also become toxic: chromium(III) is an essential trace element, but chromium(VI) is a carcinogen. Only soluble metal-containing compounds are toxic.
Smog is a serious problem in many cities and continues to harm human health. [30] [31] Ground-level ozone, sulfur dioxide, nitrogen dioxide and carbon monoxide are especially harmful for senior citizens, children, and people with heart and lung conditions such as emphysema, bronchitis, and asthma. [14]