According to the Greenpeace South Asia report: “air pollution will cause around 7 million premature deaths globally next year and have a major economic impact”. Also mentioned Bangladesh, one of the most densely-populated countries in the world, has been struggling with air pollution for long. Dhaka, the country’s capital, often finds its place among the most polluted cities in global indices.

The report focuses on PM2.5 as a measurement of air pollution. PM2.5 refers to particulate matter (ambient airborne particles) which measure up to 2.5 microns in size, and has a range of chemical makeup and sources. “Pollution is not a new phenomenon; it is largely controllable and often avoidable, but considerably neglected”.

Meteorological conditions play a crucial role in ambient air pollution by affecting both and directly and indirectly the emissions, transport, formation, and deposition of air pollutants.

Bangladesh Present Scenario:

Dhaka, the capital city of Bangladesh, is one of the air pollution hotspot among the megacities in the world; however, the potential meteorological influences on criteria air pollutants for this megacity are remained less studied. The objectives of this research were to examine the relationships between meteorological parameters such as daily mean temperature (o C), relative humidity (%) and rainfall (mm) and, the concentration of criteria air pollutants (SO2, CO, NOx, O3, PM2.5 and PM10) from January, 2013 to December, 2017. This study also focused on the trend analysis of the air pollutants concentration over the period. Spearman correlation was applied to illustrate the relationships between air pollutants concentration and temperature, relative humidity and rainfall. Multiple linear and non-linear regressions were compared to explore potential role of meteorological parameters on air pollutants’ concentrations. Trend analysis resulted that concentration of SO2 is increasing in the air of Dhaka while others are decreasing. Most of the pollutants resulted negative correlation with atmospheric temperature and relative humidity, however, they showed variable response to seasonal variation of meteorological parameters

Study Area:

Dhaka is located in the central part of the country (23°41’N latitude and 90°22’E longitude) lying on the lower reaches of Ganges Delta. It covers a total area of 306.38 km2. Dhaka is vulnerable to flooding in heavy rainfall and a cyclone during rainy season due to its topographical condition as it is flat and close to sea level. The city is surrounded by Gazipur, Tangail, Munsiganj, Narayanganj and Rajbari districts. This study utilized continuous air quality data from three Continuous Air Monitoring Stations (CAMS) in Dhaka namely Parliament area (CAMS1), Bangladesh Agricultural Research Council (BARC, Farmgate Area, CAMS2) and Darus Salam (Mirpur, CAMS3) established by DoE, MoEFCC, Governtment of Bangladesh under the Clean Air and Sustainable Environment (CASE) project. Fig. 1 shows the map of study area with continuous air pollutants monitoring stations installed in Dhaka city.

Data collection:

Air quality data consisted of daily mean concentration of six criteria air pollutants such as PM10 (µg/m3), PM2.5 (µg/m3), NOx (µg/m3), CO (ppm), O3 (µg/m3), and SO2 (µg/m3) over the period of January 2013 to December 2017 were collected from Clean Air and Sustainable Development (CASE) project, Ministry of Environment, Forest and Climate Change, Government of Peoples Republic of Bangladesh. CASE records concentrations of air pollutants of Dhaka hourly from three continuous air monitoring stations indicated in Fig. 1. For measuring concentrations of PM2.5 and PM10 an automatic

and real time suspended particulate monitor (Beta Gauge 101M; ENVIRONMENT SA, France) was installed in each three stations. Chemiluminescence gas analyzer AC32M and UV-Fluorescence AF22M (TELEDYENE/API, USA) were used to monitor concentrations of NOx and SO2 respectively. For measuring O3 an UV photometric Ozone analyzer-42M and a Dispersive Infra-Red carbon monoxide analyzer-12M (ENVIRONMENT SA, France) was used to measure concentration of CO from all three CAMS installed in Dhaka.

Basic Composition of Air

Air composes of several gases in various quantities, chief of these gases being Nitrogen, Oxygen, and Argon. Apart from it several traces or carbon dioxide, helium, and neon are also found in the air. But our body has a mechanism to disintegrate the air molecules and take what it needs, discarding what it does not require. For living beings to sustain, ideally a very small concentration of oxygen is required. Humans and animals can both survive on a maximum of 23% of the gas. Anything more than that may not be very harmful, but will also not be favorable.

Factors behind the situation: ONE
Rust Corrosion: when iron (Fe) reacts with oxygen (o2) in the air, iron oxide (F3203) is formed. The rusting process is affected by water and the key reaction involves the formation of hydroxide ions as a result of oxygen in the air and moisture (h2o) combination. In this reaction, for those in higher level chemistry. It is important to recognize which atoms are being oxidized and which atoms are being reduced. In the iron oxide reaction: Fe is being oxidized and oxygen is being reduced.

Factors Visualization:

Factor behind the situation : TWO

Engine Overheating: Fossil fuels are the causes of overheating engines of Transpiration vehicles, Generator of Industry and Power Plant. Fossil fuels contained a high percentage of carbon and hydrocarbons. Fossil fuels are Natural Gas, Petroleum and Coal.

Fossil fuels cause environmentally unsafe compounds to form in the atmosphere, depleting ozone levels and thus creating a spike in skin cancer rates. Burning coal releases sulfur oxide while the combustion of car engines and power plants gives off nitrogen oxides, which cause smog. Water and oxygen bonding with those sulfur and nitrogen oxides also causes acid rain, which damages plant life and food chains. Areas of high air pollution indexes have populations with higher rates of asthma than cleaner environments do.

Factors Visualization:

Air Pollution Impact periodization:

Air pollution is the world’s single greatest environmental risk to health, prematurely killing some 6.5 million people across the world every year and exposing nine out of ten people to unacceptable outdoor air pollution levels. It in particular affects women, children, the sick and elderly, and those in low-income groups: 300 million children live in areas where outdoor air pollution is at least six times higher than health guidelines. Particulate matter (PM2.5 and PM10) affects more people than any other air pollutant, and levels of PM2.5 have remained largely constant despite efforts to tackle the problem. Air pollutants parameters i.e. Sulfur dioxide (SO2), Carbon-mono-oxide (CO), Nitrogen oxides (NOx), Ozone (O3), PM2.5 and PM10 and meteorological parameters i.e. temperature, rainfall and relative humidity are primary impacts.

According to the UNEP’ Impacts Sources:

Tertiary Pollutant

Water:

Rust-Corrosion is a complex series of reactions between the water and metal surfaces and materials in which the water is stored or transported.The corrosion process is an oxidation/reduction reaction that returns refined or processed metal to their more stable ore state. With respect to the corrosion of potential drinking water ,the primary concerns include the potential presence of TOXIC Metals , such as lead and copper; deterioration and damage to the household plumbing, and aesthetic problems such as: stained laundry, bitter taste, and greenish-blue stains around basins and drains.

The primary source of copper is the leaching of copper from the household piping used to convey the water throughout the home.. Too bad, they did not test the water and install a neutralizing system before the piping corroded and caused leaks throughout the home. Nearly all metals will corrode to some degree. The rate and extent of the corrosion depend on the degree of dissimilarity of the metals and the physical and chemical characteristics of the media, metal, and environment. In water that is soft, corrosion occurs because of the lack of dissolved cations, such as calcium and magnesium in the water. In scale forming water, a precipitate or coating of calcium or magnesium carbonate forms on the inside of the piping, rust layer in water pump.

Water with high levels of sodium, chloride, or other ions will increase the conductivity of the water and promote corrosion. Corrosion can also be accelerated by

  1. Low pH (acidic water) and high pH (alkaline water)- For high alkalinity water – it is possible that a chemical scale may form that would help to protect against corrosion, but if a bacteria becomes established the scale, such as SRB (sulfur reducing bacteria), may experience a problem related to Microbiologically Induced Corrosion.
  2. High flow rate within the piping can cause physical corrosion;
  3. High water temperature can increase biological rate of growth and chemical corrosion;
  4. Oxygen and dissolved CO2 or other gasses can induce corrosion;
  5. High dissolved solids, such as salts and sulfates, can induce chemical or bio-chemical corrosion;
  6. If the mass ratio (CMSR) of chloride to sulfate is > 0.2, but < 0.5 there is an elevated concern, but if the CMSR is > 0.5 and the alkalinity of the water is less than 50 mg CaCO3/L the concern should be significant;
  7. Corrosion related bacteria, high standard plate counts, and electrochemical corrosion can result in pinhole leaks, isolated corrosion, and aesthetic water quality problems,
  8. Presence of suspended solids, such as sand, sediment, corrosion by-products, and rust can aid in physical corrosion and damage and facilitate chemical and biochemical corrosion.

Land:

Corrosive soils are responsible for the deterioration of buried underground utilities such as buried steel pipes. Frequent pipe failures are reported due to corrosive soil globally. Although soil’s corrosion phenomenon has been understood and identified long time ago, pipe failures due to corrosive soil are uncontrollable and unavoidable despite the use of protective coatings and techniques such as cathodic protection.

Among the various factors, the acidity (pH) and moisture contents of soil are stated as the most important key factors influencing corrosion of buried pipes. The other notable chemical constitute of the soil, i.e., chloride, well known for its corrosion-causing capability particularly to reinforce concrete structures can be responsible to the failure of steel, MS pipes.

Many Factors in soils cause external rust-corrosion of buried pipe. The moisture content of soils plays a major role in the corrosion of buried ferrous metal pipes until a limit is reached where a decline in corrosion rates takes place. Several researchers have investigated the effect of moisture content on the corrosion of buried ferrous metals.

Relationship between moisture content and corrosion rate for metal in soil. The corrosion rate of metal in soil increases with increase in moisture contents up to critical moisture contents. After critical moisture, corrosion rate starts decreasing. After critical moisture, the supply of oxygen to the metallic surface reduces, which causes a decrease in corrosion rate. Critical moisture is not a fixed value and dependent on soil type, metal type, and exposure duration and exposure condition.

Economical Loss:

The economic development of any region, state or country, depends not only on its natural resources and productive activities, but also on the infrastructure that account for the exploitation, processing and marketing of goods. Irrigation systems, roads, bridges, airports, maritime, land and air transport, school buildings, offices and housing, industrial installations are affected by corrosion and therefore susceptible to deterioration and degradation processes.

Rust is a worldwide crucial problem that strongly affects natural and industrial environments. Today, it is generally accepted that corrosion and pollution are interrelated harmful processes since many pollutants accelerate corrosion and corrosion products such as rust, also pollute water bodies. Both are pernicious processes that impair the quality of the environment, the efficiency of the industry and the durability of the infrastructure assets.

Although costs vary in relative significance from industry to industry, several generalized elements combine to make up the total cost of corrosion. Some are readily recognized; other careless recognizable. In manufacturing, corrosion costs are incurred in the product development cycle in several ways, beginning with the materials ,energy ,labor, and technical expertise required to produce a product.Otheroperatingcostsareaffectedbycorrosionswell.Corrosioninhibitors, for example, often must be added to water treatment systems.