In photochemical smog, nitrogen oxides react with parallel emissions of VOCs in the presence of sunlight to produce a wide ranging chemical cocktail of compounds, such as ozone and PAN peroxyacetyl nitrate. Ozone concentrations in urban areas are kept low because ozone reacts with nitric oxide NO emitted from vehicles and other combustion sources to give nitrogen dioxide NO 2. By contrast, when the plume of air moves out into rural areas, ozone concentrations are raised to much higher than background values, because the rate of ozone production by sunlight is catalysed by the presence of NO 2.
Eventually, the oxidation of NO 2 proceeds to form nitric acid vapour, which rapidly reacts with ammonia in the atmosphere to form small particles. The VOCs emitted by traffic and vegetation are also oxidised in conditions of strong sunlight to form small organic particles in the atmosphere.
The loss of visibility occurs as the number of airborne particles increases, and is most obvious during "photochemical episodes", which are promoted in conditions of strong sunshine and low windspeeds. A further reduction of visibility occurs as these aerosol particles grow. Much of the aerosol that contributes to PM 10 and PM 2. This means that that in conditions of high humidity the aerosols grow by absorbing water vapour, although not to the extent that occurs in fog formation.
Hence visibility may be low on days with high aerosol loading and when humidity is high. Since rain scavenges aerosol particles from the atmosphere, some of the best visibility days occur after strong rain events.
Reduce electricity usage. Burning coal is the primary source of electrical production, so avoid excessively using electricity. Turn off lights, air conditioning and electronic devices when not in use. Arrange to be involved in a local car pool or use public transportation instead of driving. According to Carpool Connect,"Higher occupancy rates also can reduce consumption of oil, thereby reducing corresponding political and economic risks, emissions of greenhouse gases and common pollution.
Install solar panels at your household. Since solar panels create energy from the sun, very little pollution is created except for the energy required to manufacture the panel itself. Solar panels are a great way to save on the electric bill and obtain free energy year-round.
Petition your community to increase public transportation. It's often cheaper to use and can cause a major smog reduction in urban areas. Make a goal to contribute daily to reducing smog in your local community.
As a result, around 7, residents suffered from various breathing problems and were hospitalised. At least 20 residents died within days. Similarly, Beijing suffered major air pollution in due to burning of coal, which caused , premature deaths. These environmental disasters did not happen in a day. There were many alarming signs, like the ones we are witnessing in Delhi nowadays.
For cities located in river basins and surrounded by mountains, smog is a persistent problem because trapped smog in the valley cannot be carried by the wind. Primary pollutants are the ones that contribute to smog formation and are emitted directly from the source. Secondary pollutants form in the atmosphere by chemical interactions of primary pollutants with normal environmental conditions. The key pollutants that lead to air pollution are oxides of nitrogen, especially nitrogen oxides and nitric oxides, which are released in the atmosphere by combustion of fossil fuel coming from coal power plants, factory emissions and car exhausts.
Nitrogen dioxide is a serious air pollutant, which, on inhalation, causes pulmonary edema an accumulation of excessive fluid in the lungs. Moreover, it contributes to photochemical smog, thus, causing serious damage to the environment. Some less visible pollutants include halogen, containing compounds like chlorofluorocarbons CFCs. Sulfurous smog and photochemical smog are two distinct types of smog recognised so far.
Sulfurous smog, also known as London smog, develops due to high concentration of sulfur oxides in the air. This gas is a serious air pollutant, causing irritation to human eyes, nose and lungs.
It is released into the air by sulfur-bearing fossil fuels like coal. Volcanoes also emit sulfur dioxide in the atmosphere.
It is estimated that the emission of sulfur dioxide by natural sources is 24 per cent, whereas anthropogenic sources contribute the rest 76 per cent. Photochemical smog is produced when sunlight reacts with oxides of nitrogen and at least one volatile organic compound VOC in the atmosphere. The chemical formation of air-borne particles and ground-level ozone takes place in the sunlight. Paints, gasoline and many cleaning solvents release VOCs into the atmosphere.
The aromatic compounds like benzene, toluene and xylene are carcinogenic and may cause leukemia. It is found that VOCs may indirectly contribute to respiratory and other ozone-related problems. It is well known that ozone layer protects us from harmful UV rays. However, the ozone close to the ground is harmful, especially for those suffering from respiratory diseases like asthma.
It can damage lung tissues, lead to itchy and burning eyes, interfere with photosynthesis and cause suppression in plant growth. To address adverse effects of fatal smog on human health, we referred to real time air quality data collected by the Central Pollution Control Board Nov , The objective was to analyse the effect of the most troublesome factors associated with smog—particulate matters PM 2.
Fine particulate matter PM 2. These particles arise from vehicle and industrial emissions, road dust, tire wear, construction, wood-burning and agriculture. Fuel combustion and chemical reactions lead to the formation of PM 2. This causes incessant cough, asthma and may even lead to lung cancer.
The levels were the highest between Nov 7 and 9, especially at ITO, as it experiences heavy vehicular traffic and is a transit point for intercity travel. PM 10 dust particles have greater aerodynamic diameter and mostly originate from road dust. Just as in the case of PM 2. Sulfur oxide is formed by combustion of sulfur-containing fuels in vehicles, gensets or thermal power plants, which use low-quality furnace oil.
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