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The chemical reactions that form smog following a volcanic eruption are different than the reactions that form photochemical smog. The term smog encompasses the effect when a large number of gas-phase molecules and particulate matter are emitted to the atmosphere, creating a visible haze. The event causing a large number of emissions can vary ...
The major acute effects of UV irradiation on normal human skin comprise sunburn inflammation erythema, tanning, and local or systemic immunosuppression. [44] The most deadly form, malignant melanoma, is mostly caused by indirect DNA damage from UVA radiation.
In organic chemistry, peroxyacyl nitrates (also known as Acyl peroxy nitrates, APN or PANs) are powerful respiratory and eye irritants present in photochemical smog. They are nitrates produced in the thermal equilibrium between organic peroxy radicals by the gas -phase oxidation of a variety of volatile organic compounds (VOCs), or by aldehydes ...
It is a secondary pollutant present in photochemical smog. [1] It is thermally unstable and decomposes into peroxyethanoyl radicals and nitrogen dioxide gas. [2] It is a lachrymatory substance, meaning that it irritates the lungs and eyes. [3] Peroxyacetyl nitrate, or PAN, is an oxidant that is more stable than ozone. Hence, it is more capable ...
Photochemical immersion well reactor (50 mL) with a mercury-vapor lamp.. Photochemistry is the branch of chemistry concerned with the chemical effects of light. Generally, this term is used to describe a chemical reaction caused by absorption of ultraviolet (wavelength from 100 to 400 nm), visible (400–750 nm), or infrared radiation (750–2500 nm).
This effect is a response of the skin called erythema, which is caused by a sufficient strong dose of UV-B. The Sun's UV output is divided into UV-A and UV-B: solar UV-A flux is 100 times that of UV-B, but the erythema response is 1,000 times higher for UV-B. [ citation needed ] This exposure can increase at higher altitudes and when reflected ...
Photoprotection of the human skin is achieved by extremely efficient internal conversion of DNA, proteins and melanin. Internal conversion is a photochemical process that converts the energy of the UV photon into small, harmless amounts of heat.
Some photosensitizing agents, such as St. John's Wort, appear to increase the incidence of inflammatory skin conditions in animals and have been observed to slightly reduce the minimum tanning dose in humans. [35] [36] Some examples of photosensitizing medications (both investigatory and approved for human use) are: St. John's Wort [36] 9-me-bc ...