Question

What is an example of natural air pollution?
A.Vehicle exhaust
B.Industrial emission
C.Volcanic ash
D.Cigarette smoke

Answer 1

When air is contaminated with any chemical, physical, or biological agent it is called air pollution. It is the largest environmental health risk leading to millions of deaths around the world each year. Air can be polluted by:
1. Natural or biogenic sources like pollen, bush fires, or dust from the desert.
2.Human sources or anthropogenic sources like burning fossil fuel, motor vehicles.

Complete answer: Classification of air pollutants.
A wide variety of pollutants are present in the atmosphere. To understand their impact on health and ecology, and to evolve appropriate strategies for their control, the pollutants are classified in several ways:
(1) source of emission,
(2) Physico-chemical characteristics
(3) effects on life processes.
Sources of air pollutants: The pollutants present in atmospheric air originate either from natural sources or man-induced activities. Natural sources of pollutants include geochemical contamination, photochemical reactions, change in climatic conditions, volcanic eruptions, gaseous discharge from marshes and swamps, forest fires, dust, fog, and radiation fall-outs. Also, a variety of microbial agents present in the lithosphere may contaminate air, especially during turbulent weather conditions. Atmospheric disturbance provides favorable conditions for the transmission of pathogens and microbial spores over long distances from areas of epidemics/pandemics. Naturally occurring microbial processes may also cause a spillover of microorganisms to the atmosphere. Man-made sources of atmospheric pollutants are concerned mainly with combustion processes (use of wood, coal, petroleum products, gas, and incineration). The extensive proliferation of the automobile industry has contributed immensely to the deterioration of air quality across the globe. It has led to environmental pollution due to oxides of sulfur and nitrogen, carbon monoxide, smoke, and fly ash. Oil refineries also contribute significantly in this regard. Manufacturing processes, iron/steel mills, fertilizer plants, and rendering units release varying amounts of metal fumes and fluorides into the atmosphere. With the growth of agricultural, textile, paper, and pharmaceutical industries, a variety of toxic residues and gases/vapors are discharged into the atmospheric air. Release of pesticide and drug residues, metallic (lead and arsenic) discharges and hydrocarbons are important air contaminants in this context. Dust particles originating from milling, crushing, and grinding units especially during road/highway building operations are responsible for lowering the quality of air, especially in the urban and semi-urban areas.
Option -A-Vehicle exhaust: Air pollution by vehicle exhaust is driven by anthropogenic activity and not by natural sources.
Option -B-Industrial emission: Air pollution via industrial emission is also driven by human activities and not by natural sources.
Option -C-Volcanic ash: Volcanic ash is a natural source of air pollution without any human intervention.
Option -D- Cigarette smoke: Cigarette smoke also is a man-made source of air pollution. It has nothing to do with a natural source.
So, the correct answer is option C "Volcanic ash"

Note: Air pollutant means any solid, liquid, or gaseous substance including noise present in the atmosphere in such concentration as may tend to be injurious to human beings, living creatures, plants, properties, or environment whereas Air pollution means the presence of air pollutant in the atmosphere. The Air (Prevention & Control of Pollution) Act was given in 1981.