Science Makes Sense-Week 28: Chemistry and Social Justice, Air Pollution in India

I go to India in December to be with my siblings and spend most of my time in Chennai, a south-eastern city along the Bay of Bengal. Every year I notice that construction is booming with more and more multi-story structures and houses all over the city. Apart from that, vehicular traffic on the roads keeps increasing. This year I found myself struggling with a hacking cough and continuous throat irritation.
There is an urgent need to address air pollution here. It is important to understand the unique blend of pollutants present in India versus countries like the United States. As students of science one needs to have a general idea about measurement techniques as well. As social justice advocates it is imperative to look at the alarming health effects to the citizens and what measures are being taken to counteract this.
Even though the capital of India, New Delhi, is considered to have the worst Air Quality Index (Ref.1), or AQI, Chennai, seemed to be worse than new Delhi in 2015.(Ref.2)
What is AQI? Basically it is an index that lets one know how polluted or safe the air quality is in a particular country. Depending on the industries and the culture of daily life prevalent in the country, there are several different pollutants present in the air. One usually calculates its concentration for a 24 hour period in 3 -4 hour intervals. The AQI ranges from 0- 500+ and the higher the value the more polluted is the air. Several countries use a color code to indicate the levels of different pollutants ranging from safe to highly polluted/dangerous.(Ref.3) In the US, we often hear about ozone levels and PM2.5 and PM10 along with a few chemicals like sulfur dioxide etc.(PM2.5 is particulate matter less than 2.5 microns in diameter and PM10 is particulate matter less than 10 microns in diameter. A grain of sand is 50-70 microns in diameter. A micron is one millionth of a meter.)
In India, apart from the above mentioned pollutants the presence of nitrogen dioxide, ammonia,lead, benzene, nickel, carbon monoxide, arsenic levels are calculated to measure AQI.(Ref.4)
Why does India have all these extra air pollutants? As a rapidly industrializing country, there is a lot of coal production that leads to incomplete combustion forming carbon black(particulate matter,soot), carbon monoxide as well as lead, arsenic and oxides of nitrogen and sulfur.(Ref.5) Ammonia is present in decaying garbage, excreta as well as in pesticides.(Ref.6) Benzene and other such aromatic hydrocarbons are present because there is indoor air pollution especially in rural households where biomass, which is plant waste matter,(Ref.7) is burned during cooking, along with incomplete combustion products like carbon, carbon monoxide.(Ref.8) Nickel is present also in fossil fuel emissions as well as in the cement industry.(Ref.9)As you can see, India poses unique problems because of very severe indoor and outdoor pollutants.
The measurements of these pollutants is done using statistical analysis, gravimetric (where the element or compound being studied is isolated in a solid form and weighed)studies. In some cases, based on the chemical properties of the pollutants chemiluminescence, specroscopy as well as gas chromatography are some of the other tools utilized to do some quantitative analysis.(See Nuggets for more clarification of new terms.) All the measurements are done in terms of micrograms of the pollutant per cubic meter.(Ref.4)
Once the measurements are done for the 24 hour period, the range of pollutants present decides how safe or hazardous the air quality is for the day. 6 color codes are used in India; the safest is when the pollutants present is below 50 micrograms per cubic meter; satisfactory is around 50-100 micrograms per cubic meter; 101-200 micrograms per cubic meter is moderately polluted whereas 200 and higher will be classified under poor, very poor and severe conditions.(Ref.10)
The Air Quality Index determines the level of pollutants and as already pointed out, certain major cities in India constantly surpass safe levels many days of the year. People with asthma and other lung infections are particularly prone to severe attacks and the color codes advise them to stay indoors. However, even people with no specific health problems are prone to get headaches, coughs and throat irritations. As the threat level increases from moderately polluted to higher levels, more serious health issues are observed with the populace. There are respiratory diseases, problems during pregnancy and sometimes even death due to dangerous levels of air pollution.(Ref.11)
What is being done to combat these problems? In New Delhi, where the AQI is consistently one of the worst in the world,the government decided in early January of this year to have half the cars on the street, by having odd-even licence plate cars on the street on alternate days. Initially not much improvement was seen in the AQI, but with time and the additional factor that more people started using public transportation, the air quality has considerably improved. (Ref.1)
There is also the feeling that the Supreme court in India has the power to mandate certain reforms. Earlier in the 80’s the court mandated that compressed diesel should be used in the Delhi city buses and that did improve air quality for a while. The legislature now should go for a 30 percent tax on the sale of diesel vehicles, charge higher automobile registration and parking fees, and get more buses on Delhi’s roads. Then the Supreme Court could use its authority to order compliance with these recommendations. Finally, India’s national air-quality standards must be made legally binding.(Ref.12)
The Center for Science and Environment (CSE) is a public interest research and advocacy organisation in New Delhi. CSE researches into, lobbies for and communicates the vital need for development that is both sustainable and equitable. They believe in balancing the rural based life style of doing sustainable agriculture using biomass with the rapidly industrializing urban world in India. CSE brings out a lot of pamphlets and information articles to educate, promote the need for better air quality and care for the environment while rapidly developing.(Ref.13)
The fact that more and more people are aware of AQI is a start. There is even a smart phone app for AQI and most Indians love their smart phones!(Ref.14) Civic awareness can play a major part in a country where it was citizens who clamored for reform and created the Aam Aadmi Party(The Common man’s Party) in New Delhi to create positive change. In addition, India is cutting dependence on fossil fuels by looking seriously at alternative green sources like solar energy. But the pollution is still there, there are many deaths and severe illnesses reported in India because of poor air quality and so we have a long way to go.
Activities for Middle School Teachers
Why does New Delhi have such high AQI numbers? It could have something to do with the fact that it is landlocked and the smog presence is similar to Mexico City and Los Angeles. Study geographical reasons that might exacerbate or mitigate air pollutant levels. Would sea breezes help or hinder this process?
Look at a few major cities in the world to compare and contrast air pollutants. Why do they differ?
If students have smart phones, let them study AQI in a few regions all over the world for different months of the year and plot days from different months against AQI. Is there a correlation, any pattern seen?
Study all the quantitative techniques like spectroscopy, gravimetric analysis, gas chromatography and chemiluminescence and get to use/see those instruments either at the school laboratory or through you-tube videos.
Nuggets of Information:
A Yale University research team 2014 report shows that India ranked 174 out of 178 countries in air quality, somewhere close to China and Pakistan.(Ref.15)
World Health Organization says(2014 report) New Delhi’s air quality is the worst in the world!(Ref.15)
Air Pollution is the fifth largest killer in India.(Ref.15)
The Taj Mahal is turning yellow due to coal dust, biomass burning and high fossil fuel burning in India.(Ref.16)
Chemiluminescence simply means that certain compounds emit light due to chemical reactions just like fireflies do on long summer nights.
The number of photons (quantitative measurement of light particles) emitted can help calculate the concentration of certain pollutants like nitrogen dioxide, ozone and ammonia.
Spectroscopic studies use instruments like spectrometers that are able to assay spectral data using mathematics to calculate concentrations of different compounds.
Chromatography separates several constituents in a mixture and in a gas chromatograph, one analyses the peaks, the position of the peaks and the height of the peaks to identify compounds and analyse concentrations of the compound as well.



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