In addition, rainfall may wash these pollutants out of the local atmosphere, [2] however, this can result in other unwanted events like acid rain. When smog encounters an inversion layer caused by warm areas in the upper atmosphere it can stay over a region for an extended period of time—exposing people to its effects for longer. Visit the inversion layer page to see how this phenomena occurs.
The health effects from smog and its components can be severe, and depend on many variables. Smog is harmful when inhaled, with the severity of it depending on the amount inhaled, the types of pollutants contained in it, as well as the individual's age, weight, activity level, and well-being. Types of effects smog has include: [2]. This effects can be seen in Figure 3 below, with more serious and rare effects at the top, and the more common yet milder effects towards the bottom.
Visit the Government of Canada for information of smog in Canada, and how to reduce your risk of its adverse effects. Smog affects much more than just human lives; it also has a large impact on the surrounding physical environment. Ozone and PM in particular cause damaging effects: [2]. Ozone can damage plant cells and inhibit their growth, reducing the amount of carbon dioxide that they take in during photosynthesis.
Particulate matter is directly emitted during combustion, for example from fires or diesel engines. But it also forms in the atmosphere as a result of chemical reactions involving VOCs. Airborne particulate matter reduces visibility and is the reason smog appears brown. Ground-level ozone and particulate matter are particularly harmful to respiratory health.
Breathing ozone-polluted air can cause coughing and shortness of breath, damage and inflame airways, and aggravate asthma. Airborne particles, meanwhile, are easily inhalable and can become embedded in the lungs or transferred into the bloodstream, causing serious health problems. Ozone exposure can leave plants more susceptible to disease and drought and reduce agricultural yields. Atmospheric particulate matter scatters sunlight back to space, which has a cooling effect on Earth.
Particles also provide the seeds around which nearly all clouds form. However, heavy pollution can suppress cloud formation. 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.
Sulfur oxide is converted to H2SO4 or sulfuric acid, when deposited in the nasal linings and leads to severe allergic reactions and may even cause cancer. NOx is generally formed from high temperature oxidation of diatomic atmospheric oxygen in combustion engines or furnaces. They destroy the ozone layer and cause lung damage, leading to diseases such as emphysema and asthma.
Not only outdoor, but also indoor air quality is a great concern since people consider their homes a safe refuge and become carefree.
Sources of indoor pollution are VOCs and soot from open air stoves or kerosene stoves; mold and spores from damp places, especially the washroom area, dead skin and insect particles as well as pollen from planted flowers or dust accumulated in blankets and mattresses. This problem is so common that it has been given a special name: Sick Building Syndrome.
Architects are trying to mitigate it by better ventilation, materials and design. Exposure to such indoor air pollutants may cause allergy, asthma, cardiovascular disease, memory loss, cancer and can be harmful to fetal development. A silver lining, even in this extremely precarious situation, is that Delhi is not new to facing problem of worsening air quality.
However, owing to its geography, demographics and industrial areas, Delhi has become experienced in ad-hoc and long-term mitigation strategies. Action to tackle a problem can be of two types, preventive and punitive. The Supreme Court has been at the vanguard of this fight.
Back in , it had directed all the hot mix plants, emitting noxious fumes, to be relocated out of Delhi. Catalytic converters were introduced in cars in to reduce toxicity in pollutants released by vehicle exhausts. Petroleum coke and furnace oil were banned in in Delhi, however, industrial units in NCR kept using them. At that time, it seemed like a very expensive undertaking.
The SC went a step further by banning registration of all diesel SUVs over cc and mandating that all commercial taxis also be converted to CNG by It was not only the judiciary, which is trying to reduce the pressure of air pollution on the city, but the executives, too, are taking preventative actions. Delhi government had introduced emission control norms for the first time in Since then, the standards have got stricter in the form of pollution control certificates PUC , which must be renewed every three months.
Delhi government phased out lead petrol, reduced the amount of benzene in fuel, and introduced low-sulfur diesel to provide vehicles with cleaner fuel. Mitigation measures also involved major infrastructure investments. The most prominent among them, which also tackles traffic congestion, is the creation of mass rapid transport schemes like Delhi Metro, which has taken lakhs of vehicles off the road.
This paper discuses only tropospheric ozone, not to be confused with stratospheric ozone, which forms a layer around the earth, protecting it from the rays of the sun. Tropospheric ozone is produced by the action of light and the chemical bonding of volatile organic compounds VOCs and nitrogen oxides NO x.
The table below identifies the main sources of smog-forming pollutants. A s a result of heat from the rays of the sun, the concentration of ground-level ozone is highest in urban centres in the summer.
Weather conditions also affect ozone formation; masses of stagnant air can hold pollutants at ground level for several days. Pollutant Sources, Both Natural and Human-Made Volatile organic compounds VOC Tailpipe emissions, evaporation of gasoline at service stations, surface coatings such as oil paints, solvents such as barbecue starters, fuel combustion, vegetation Nitrogen oxides such as nitric oxide NO and nitrogen dioxide NO 2 Tailpipe emissions, manufacturing industries, electricity generating stations, fossil fuel powered plants, oil refineries, pulp and paper plants, incinerators Sulphur dioxide SO 2 Non-ferrous metal smelting, thermal electricity generating stations, oil refineries, pulp and paper plants, incinerators Particulate matter Tailpipe emissions, volcanoes, wind erosion, forest fires, fossil fuel powered plants Source: Anonymous, "Health Effects of Outdoor Air Pollution," American Journal of Respiratory and Critical Care Medicine , Volume , ; Health Canada, summary of recent research on the effects of ambient air pollution on health in Saint John, Health Canada Internet Site, Sulphates: Sources, Composition, and Formation.
I n normal concentrations, sulphur dioxide SO 2 is not toxic; however, the acid pollutants into which it is chemically changed do have negative effects on health.
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