Plant growth and distribution are limited by the environment. If any one environmental factor is less than ideal it will become a limiting factor in plant growth (University of Arizona, 1998). All external conditions and influences affecting the life and development of an organism. (Stephen W. Broome, nd).
In this study, we aim to use charcoal and other burning materials which will be used to affect the different air qualities in each set-up. Pollution is the presence or an introduction into the environment of a substance which has harmful or poisonous effects.Annual losses of plant life e.g. crops, trees that are caused by air pollution are estimated to be worth more than a billion dollars (Earth Observatory, nd).
The effects of pollution on plants include mottled foliage, “burning” at leaf tips or margins, twig dieback, stunted growth, premature leaf drop, delayed maturity, abortion or early drop of blossoms, and reduced yield or quality. The pollutants also affect how the plant grows and develops, showing a change in colour of a leaf in a plant (Eduardo Zeiger, 2006). So, when the air quality is poor, there maybe a reduction in growth, and after suffering recurrent injury, they will die. It is hypothesised that if the air quality is poor, plants would not grow as much as when compared to an area with a richer air quality.
There are many factors that affect air quality, such as city size, city location, land topography, soil moisture, nutrient supply, time period, species or variety of plants. Damage caused by air pollution is usually most severe during warm, clear, still, humid weather when barometric pressure is high. Accumulation of toxicants take place near middle atmosphere when warm air aloft traps cooler air at ground level. This is called air inversion.
The burning of hydrocarbons in motor vehicle engines gives rise to Carbon Dioxide (CO₂) , Carbon Monoxide (CO), Sulfuric Dioxide (SO₂), Nitric Oxide + Nitrogen Dioxide (NOx) and sometimes, in varying proportions, Ethylene (C₂H₄). Industrial plants, such as chemical works and metal-smelting plants, release SO₂, Hydrogen Sulfide (H₂S), Nitrogen Dioxide (NO₂), and Hydrogen Fluoride (HF) into the atmosphere.
Photochemical smog is the product of chemical reactions driven by sunlight and involving NOx of urban and industrial origin. Ozone (O₃) and Peroxyacetyl Nitrate (PAN) are being produced in these reactions and they can harmful and injurious to plants and other life forms. Hydrogen peroxide (HO), another potentially injurious molecule, can form by the reaction between O₃
and naturally released volatiles (terpenes) from forest trees (Eduardo Zeiger, 2006).
The responses of plants to polluting gases can also be affected by other ambient conditions, such as light, humidity, temperature, and the supply of water and minerals. Experiments aimed at determining the impact of chronic exposure to low concentrations of gases should allow plants to grow under near-natural conditions.