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Vol. 11 No. 4 - October 2005

Looking at Fireworks From Environmental Science Perspective

By: Arun K. Attri

Without any hesitation it can be stated that the sparkling and twinkling of coloured lights exhilarates the visual senses of one and all. When this display is coupled with the sound of explosive bursts it is considered an expression of joyous affair; occasion can be marriage, new year, Diwali or any other festival. On the other hand, scientific evidence is mounting to reveal the immediate impact of such firework displays on human health through pollution of air we breathe. Diwali festival had been the focus of scientific investigations related to firework displays and following adverse health impact.

In order to understand the gravity of the adverse health related impact due to the fireworks, it is important to comprehend their basic chemical composition. Firework activation represents a combustion reaction, where the mixed ingredients are burnt. The most basic form of fireworks, known as black powder, was discovered and used in China about 1000 years ago. It was a mixture of potassium nitrate, charcoal and sulfur in 75:15:10 proportion. Black powder, even today, is used as an explosive charge and propellant in shells and bullets. On ignition the mixture produces, instantaneously gases and if the mixture is confined inside a closed space explosion follows. The directed emission of gases can propel the container like a rocket. From chemistry’s point of view combustion requires the supply of oxygen; or oxidizing agent capable of supplying large amount of oxygen. Commonly known oxidizers used in fireworks are nitrates, chlorates and per-chlorate compounds. Reducing agent capable of burning in the presence of oxygen supplied by the oxidizer acts as fuel; sulfur and charcoal are few common reducers used in making the fireworks. The loose mixture of oxidizer and reducer is shaped and held together by using binding agent; starch dextrin or gum arabic are common binders used to make the mixture more evenly homogeneous. Bright sparkling colours emitted by different types of fireworks require the addition of metal salts in black powder. Depending upon the composition of oxidizer and reducer used, fireworks on ignition can achieve very high temperature (1000 to 3000 0C). Metals, when heated, at such temperatures, emit radiation covering a wide spectral range, which includes the visible light of characteristic colour.

Some of the common metal salts used to achieve the emission of sparkling colours are: (a) Copper Acetoarsenate [Blue], (b) Copper chloride [Turquoise], (c) Cryolite [Yellow], (d) Lithium Carbonate [Brilliant Red], (e) Barium Carbonate [Green], (f) Barium Chloride [Bright green] etc. In addition, the emission of bright white sparkling light flashes effects require the mixing of magnesium and aluminum salts into the mixture. The human eye can only see the radiation emitted in visible spectral region. One of the little known aspects associated with metal salts emitting radiation or light, when heated at high temperature, was revealed in 2001(Nature vol 411, pp 1015).

Experiments clearly provided evidence that in addition to the emitting of visually elating colours, metals at high temperature also emit radiation in spectral region known as ultraviolet or UV. Barium, copper, lithium, strontium, manganese, sodium salts when burnt at temperatures produced by the ignition of fireworks emit significant proportion of light having wavelength less than 240 nm (high energy UV radiation).  Consequences of this are alarming. First, the person standing in the vicinity, where fireworks are ignited, will be exposed to harmful UV radiation. Second, the high energy UV radiation are readily absorbed by molecular oxygen present in the air. This results in the splitting of molecular oxygen into atomic oxygen [O2 + UV(Wavelength <240 nm ) à O + O].

Now, this is serious as atomic oxygen (O), thus produced, is chemically very reactive and on reaction with molecular oxygen produces ozone (O3), a powerful oxidant. The experiments done recorded precisely this. Fireworks emitting colour on ignition produced a burst of O3 production in the air surrounding the ignited fireworks. This new finding unfolded another dimension associated with firework displays, i.e. in addition to their potential to pollute the air. Air we breathe, if contains ozone (powerful oxidant) will damage the lung lining. The damage is likely to be more among children.

In the wake of new scientific evidence, let us reflect upon what all we know about the consequences of extensive firework displays, as it happens on Diwali, New year, or any community related festive occasion, taking into account the meteorological factors prevailing during their celebrations.

  1. Large scale firework displays coincides with the onset of the winter season. From sunset till morning, atmospheric mixing height is low as compared to summer season. In simple terms, whatever pollutants are injected into the lower atmosphere, have less volume to mix in. This results in the further concentrating the air pollutants.

  2. It is already established that the levels of suspended particulate load (SPM), CO, NOx, Hydrocarbons, SO2 increase to an unprecedented levels in air. Pregnant women, children and those having a chronic asthma are most vulnerable to the serious medical condition during firework displays.

  3. UV light and ozone exposure make conditions more undesirable.

  4. Meteorological conditions favour calm winds and this will ensure removal of pollutants produced from fireworks hangs in the air for long duration.

One of the most desirable aspect of our life is to have a good quality of life, this requires that we respect the right of every other individual to pursue the same.  So, even if we have a great urgent desire to ignite fireworks to seek personal gratification, we should look again, are we not encroaching on the natural rights of others to seek the availability of pollution free air to breathe? Best celebrations are not at the cost of making others unhappy.  It is time to seek pollution free air and water and aspire for better quality of life saying no to the fireworks will be a big step towards attaining it.

Prof. Arun K. Attri is Professor at School of Environmental Sciences, Jawaharlal Nehru University, New Delhi- 110 067, India (
[email protected])

This article has been reproduced from the archives of EnviroNews - Newsletter of ISEB India.

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