What is the meaning of photochemical oxidants?
The photochemical oxidants are secondary air pollutants formed by the action of sunlight on nitrogen oxides and reactive hydrocarbons, their precursors. The most important phytotoxic components produced by these atmospheric photochemical reactions are ozone and peroxyacetyl nitrate.
What are photochemical oxidants give two examples?
The photochemical oxidants are secondary air pollutants formed by the action of sunlight on nitrogen oxides and reactive hydrocarbons, their precursors. The most important photochemical oxidants produced by these atmospheric photochemical reactions are ozone and peroxyacetyl nitrate (PAN).
What is the chemical composition of photochemical smog?
The major undesirable components of photochemical smog are nitrogen dioxide (NO2), ozone (O3), PAN (peroxyacetylnitrate), and chemical compounds that contain the –CHO group (aldehydes). PAN and aldehydes can cause eye irritation and plant damage if their concentrations are sufficiently high.
What are the effects of photochemical oxidants?
Photochemical Smog The atmospheric oxidation of VOCs leads to two important by-products in the lower atmosphere, ozone and organic aerosol, which have important consequences for air quality and climate. Ozone and organic aerosol have direct health effects on humans, as they are harmful to our respiratory system.
Which of the following is a major photochemical oxidants?
The most commonly known photochemical oxidants are ozone, hydrogen peroxides and peroxyacetyl nitrate (PAN). These are formed under the influence of sunlight by complex photochemical reactions.
Is methane a photochemical oxidant?
The photochemical oxidation of volatile hydrocarbons is by far the largest natural source of H2. The reaction of methane (CH4), the most abundant hydrocarbon in tropospheric air, with hydroxyl radicals (OH) initiates a reaction sequence (reaction[I]–[IV]) that produces formaldehyde (HCHO).
What does the term photochemical mean?
Definition of photochemical 1 : of, relating to, or resulting from the chemical action of radiant energy and especially light photochemical smog. 2 : of or relating to photochemistry photochemical studies.
What is the difference between classical smog and photochemical smog?
The key difference between classical smog and photochemical smog is that classical smog forms due to humid climate, whereas photochemical smog forms due to smoke coming from automobiles and factories. Moreover, classical smog forms in cool, humid climates, while photochemical smog forms in dry and sunny climates.
What is the composition of photochemical smog Mcq?
5. What is the composition of photochemical smog? Explanation: The photochemical smog constitutes of oxides of nitrogen, aldehydes, ketones, ground level ozone as well as PAN, PBN, PFN which are the free radicals formed due to reaction of ketones, nitrogen oxides and oxygen in the presence of sunlight.
What is the chemical reaction for smog?
Smog is formed when sunlight interacts with hydrocarbons and nitrogen oxides released into the air by cars and power plants. A highly reactive compound of oxygen and hydrogen called a hydroxyl radical kick starts that reaction. Sinha’s paper focuses on this hydroxyl radical, known as OH.
What are photochemical oxidants and why are they harmful?
These compounds are hazardous air pollutants and are the fundamental reactants required for the formation of smog. Generally, photochemical oxidants are chemical or physical contaminants that may be responsible for the onset of significant health problems.
What are photochemical oxidants?
Photochemical oxidants are the product of chemical reactions that occur between nitrogen oxide (NO) and any of a host of different volatile organic compounds (VOCs). Common or well known photochemical oxidants include ozone (O3), hydrogen peroxide (H2O2), and peroxyacetyle nitrate (PAN).
What is photochemical oxidant smog?
However, it is really the code word for photochemical oxidant smog, the brown haze that can be seen when flying into Los Angeles, St. Louis, Denver, and other metropolitan areas around the world. Smog is made up of at least three ingredients: light, hydrocarbons, and radical sources, such as the oxides of nitrogen.
What is the Los Angeles type of photochemical reaction?
The Los Angeles type is induced by photochemical action of sunlight, consisting mainly of organic compounds, nitrogen oxide and carbon monoxide; it causes temporary eye irritation, but the other effects on humans are not known. Under normal environmental conditions, vegetation can be injured.
What causes photo-oxidation of polyolefins?
Photo-oxidation of the polyolefin chains is caused particularly by the presence of hydroperoxides and to a lesser extent by the presence of carbonyl groups. 26 These photoactive species are produced in small quantities during the processing of a polyolefin fibre. Hydroperoxides possess a high initiating capacity.