NON-SOIL FUMIGATION VERIFIED EXAM QUESTIONS AND
ANSWERS - LATEST VERSION 2026/2027
Q: What is non-soil fumigation? ANSWER The use of toxic gases to
eliminate pests in commodities, structures, containers, and transport
vehicles, excluding agricultural soil.
Q: Why use fumigants instead of sprays for stored grains? ANSWER
Fumigants penetrate deep into bulk commodities where sprays and
contact insecticides cannot reach.
Q: What are the three physical states of matter, and which do fumigants
fall under? ANSWER Solid, liquid, and gas. Fumigants are utilized as
gases.
Q: What is the ideal gas law, and why is it relevant to fumigation?
ANSWER PV=nRT; it explains how temperature, pressure, and volume
affect gas concentration and behavior in a sealed space.
Q: How does temperature affect fumigant efficacy? ANSWER Higher
temperatures increase pest respiration and fumigant volatility, making the
pest more susceptible and the gas more active.
Q: What is sorption? ANSWER The process by which a commodity
absorbs or adsorbs a fumigant gas, reducing the concentration in the free
air space.
Q: What is desorption? ANSWER The slow release of a fumigant from a
commodity back into the air after the fumigation period ends.
Q: Define "fumigant concentration." ANSWER The amount of fumigant gas
present in a given volume of air, usually measured in grams per cubic
meter (g/m³) or parts per million (ppm).
Q: What does CT stand for in fumigation? ANSWER Concentration x Time.
It represents the total dose of gas the pest is exposed to.
Q: Why is the CT concept important? ANSWER It allows for flexibility; a
lower concentration over a longer time can be equally effective as a
higher concentration over a shorter time.
,Q: What is a half-life in fumigation? ANSWER The time it takes for the
concentration of a fumigant in a sealed space to reduce by half.
Q: What is leakage? ANSWER The unintended escape of fumigant gas
from a sealed enclosure.
Q: How does air currents affect fumigation inside a structure? ANSWER
Air currents can cause gas stratification or uneven distribution, leading to
cold spots and survival of pests.
Q: What is "gas diffusion"? ANSWER The natural movement of gas
molecules from areas of high concentration to areas of low concentration.
Q: What is the difference between fumigation and fogging? ANSWER
Fumigation uses true gaseous states that penetrate deeply; fogging uses
liquid droplets suspended in air that only reach exposed surfaces.
Q: Can fumigation prevent future re-infestation? ANSWER No, fumigation
has no residual effect. Once the gas dissipates, the commodity or structure
is vulnerable to re-infestation.
Q: What is a quarantine fumigation? ANSWER A mandatory treatment to
kill regulated pests to prevent their spread across national or regional
borders.
Q: What is a phytosanitary treatment? ANSWER A treatment applied to
plants or plant products to comply with phytosanitary regulations (e.g.,
ISPM 15).
Q: What does "holding period" mean? ANSWER The specific amount of
time the enclosure must remain sealed to achieve the required CT value.
Q: What is aeration? ANSWER The process of ventilating a fumigated
space or commodity with fresh air to reduce gas concentrations to safe
levels.
Q: Why is monitoring gas levels during fumigation necessary? ANSWER
To ensure lethal concentrations are maintained, detect leaks, and verify
safe levels before re-entry.
Q: What is stratification of gas? ANSWER The separation of gas layers
based on weight (e.g., heavier gases settling at the bottom), which can
lead to uneven distribution.
Q: How is stratification prevented? ANSWER By using recirculation fans
to mix the air and gas.
, Q: What is a "fumigant"? ANSWER A chemical that, at a required
temperature and pressure, exists in a gaseous state in sufficient
concentration to be lethal to pests.
Q: Name two primary targets of structural fumigation. ANSWER Drywood
termites and wood-boring beetles.
Q: Name two primary targets of commodity fumigation. ANSWER Stored
product insects (e.g., weevils, beetles) and rodents.
Q: Why are rodents difficult to kill with certain fumigants? ANSWER
Rodents can close their eyes, hold their breath, and have a lower
respiratory rate compared to insects.
Q: What is "endpoint determination" in commodity fumigation? ANSWER
The process of calculating if the actual CT achieved meets the required CT
for target pests.
Q: What happens if a commodity has high moisture content during
fumigation? ANSWER It generally increases sorption, reducing the free
gas concentration available to kill pests.
Q: What is a "target pest"? ANSWER The specific organism the fumigation
is intended to eradicate.
Section 2: Phosphine (Aluminum Phosphide / Magnesium Phosphide)
Q: What is the chemical formula for phosphine? ANSWER PH3.
Q: What are the common solid formulations of phosphine? ANSWER
Aluminum phosphide (AlP) and Magnesium phosphide (Mg3P2).
Q: What forms do AlP formulations come in? ANSWER Tablets, pellets,
plates, and sachets/blankets.
Q: How is phosphine gas generated from solid formulations? ANSWER By
a chemical reaction with atmospheric moisture (water vapor).
Q: Write the basic chemical reaction for aluminum phosphide and water.
ANSWER 2AlP + 6H2O → 2Al(OH)3 + 2PH3↑.
Q: What is the minimum relative humidity generally required for
adequate phosphine release? ANSWER Typically above 40-50%, though
formulations exist for drier conditions.
Q: At what temperature does phosphine generation significantly slow
down? ANSWER Below 10°C to 15°C (50°F to 59°F).
ANSWERS - LATEST VERSION 2026/2027
Q: What is non-soil fumigation? ANSWER The use of toxic gases to
eliminate pests in commodities, structures, containers, and transport
vehicles, excluding agricultural soil.
Q: Why use fumigants instead of sprays for stored grains? ANSWER
Fumigants penetrate deep into bulk commodities where sprays and
contact insecticides cannot reach.
Q: What are the three physical states of matter, and which do fumigants
fall under? ANSWER Solid, liquid, and gas. Fumigants are utilized as
gases.
Q: What is the ideal gas law, and why is it relevant to fumigation?
ANSWER PV=nRT; it explains how temperature, pressure, and volume
affect gas concentration and behavior in a sealed space.
Q: How does temperature affect fumigant efficacy? ANSWER Higher
temperatures increase pest respiration and fumigant volatility, making the
pest more susceptible and the gas more active.
Q: What is sorption? ANSWER The process by which a commodity
absorbs or adsorbs a fumigant gas, reducing the concentration in the free
air space.
Q: What is desorption? ANSWER The slow release of a fumigant from a
commodity back into the air after the fumigation period ends.
Q: Define "fumigant concentration." ANSWER The amount of fumigant gas
present in a given volume of air, usually measured in grams per cubic
meter (g/m³) or parts per million (ppm).
Q: What does CT stand for in fumigation? ANSWER Concentration x Time.
It represents the total dose of gas the pest is exposed to.
Q: Why is the CT concept important? ANSWER It allows for flexibility; a
lower concentration over a longer time can be equally effective as a
higher concentration over a shorter time.
,Q: What is a half-life in fumigation? ANSWER The time it takes for the
concentration of a fumigant in a sealed space to reduce by half.
Q: What is leakage? ANSWER The unintended escape of fumigant gas
from a sealed enclosure.
Q: How does air currents affect fumigation inside a structure? ANSWER
Air currents can cause gas stratification or uneven distribution, leading to
cold spots and survival of pests.
Q: What is "gas diffusion"? ANSWER The natural movement of gas
molecules from areas of high concentration to areas of low concentration.
Q: What is the difference between fumigation and fogging? ANSWER
Fumigation uses true gaseous states that penetrate deeply; fogging uses
liquid droplets suspended in air that only reach exposed surfaces.
Q: Can fumigation prevent future re-infestation? ANSWER No, fumigation
has no residual effect. Once the gas dissipates, the commodity or structure
is vulnerable to re-infestation.
Q: What is a quarantine fumigation? ANSWER A mandatory treatment to
kill regulated pests to prevent their spread across national or regional
borders.
Q: What is a phytosanitary treatment? ANSWER A treatment applied to
plants or plant products to comply with phytosanitary regulations (e.g.,
ISPM 15).
Q: What does "holding period" mean? ANSWER The specific amount of
time the enclosure must remain sealed to achieve the required CT value.
Q: What is aeration? ANSWER The process of ventilating a fumigated
space or commodity with fresh air to reduce gas concentrations to safe
levels.
Q: Why is monitoring gas levels during fumigation necessary? ANSWER
To ensure lethal concentrations are maintained, detect leaks, and verify
safe levels before re-entry.
Q: What is stratification of gas? ANSWER The separation of gas layers
based on weight (e.g., heavier gases settling at the bottom), which can
lead to uneven distribution.
Q: How is stratification prevented? ANSWER By using recirculation fans
to mix the air and gas.
, Q: What is a "fumigant"? ANSWER A chemical that, at a required
temperature and pressure, exists in a gaseous state in sufficient
concentration to be lethal to pests.
Q: Name two primary targets of structural fumigation. ANSWER Drywood
termites and wood-boring beetles.
Q: Name two primary targets of commodity fumigation. ANSWER Stored
product insects (e.g., weevils, beetles) and rodents.
Q: Why are rodents difficult to kill with certain fumigants? ANSWER
Rodents can close their eyes, hold their breath, and have a lower
respiratory rate compared to insects.
Q: What is "endpoint determination" in commodity fumigation? ANSWER
The process of calculating if the actual CT achieved meets the required CT
for target pests.
Q: What happens if a commodity has high moisture content during
fumigation? ANSWER It generally increases sorption, reducing the free
gas concentration available to kill pests.
Q: What is a "target pest"? ANSWER The specific organism the fumigation
is intended to eradicate.
Section 2: Phosphine (Aluminum Phosphide / Magnesium Phosphide)
Q: What is the chemical formula for phosphine? ANSWER PH3.
Q: What are the common solid formulations of phosphine? ANSWER
Aluminum phosphide (AlP) and Magnesium phosphide (Mg3P2).
Q: What forms do AlP formulations come in? ANSWER Tablets, pellets,
plates, and sachets/blankets.
Q: How is phosphine gas generated from solid formulations? ANSWER By
a chemical reaction with atmospheric moisture (water vapor).
Q: Write the basic chemical reaction for aluminum phosphide and water.
ANSWER 2AlP + 6H2O → 2Al(OH)3 + 2PH3↑.
Q: What is the minimum relative humidity generally required for
adequate phosphine release? ANSWER Typically above 40-50%, though
formulations exist for drier conditions.
Q: At what temperature does phosphine generation significantly slow
down? ANSWER Below 10°C to 15°C (50°F to 59°F).
