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Key Facts: Engineer Air Pollution Environmental Exam

80 Items

Written examination questions from 2026 (20 items x 4 subjects)

HRD Korea / Q-Net 출제기준

120 Mins

Total written testing time (30 minutes per subject)

Q-Net examination guide

KRW 19,400

Written examination registration fee

HRD Korea fee schedule

KRW 22,600

Practical examination (대기오염관리 실무) fee

HRD Korea fee schedule

60 Points

Overall pass mark, with at least 40 points required in every subject

National Technical Qualifications Act

80 MCQs

Questions in this independent English-language study bank

OpenExamPrep practice bank

Administered by HRD Korea (한국산업인력공단 / Q-Net), the Engineer Air Pollution Environmental (대기환경기사) written examination is 80 four-option multiple-choice questions across 4 subjects in 120 minutes, with at least 40 points required in every subject and 60 points overall. Written fee KRW 19,400; practical fee KRW 22,600. This 80-question bank is an independent English-language MCQ study adaptation by OpenExamPrep — not an official translation or format simulation — built to the subject list that took effect on 1 January 2026.

Sample Engineer Air Pollution Environmental Practice Questions

Try these sample questions to review concepts for the Engineer Air Pollution Environmental exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 80+ question experience with AI tutoring.

1Which of the following correctly describes the vertical temperature profile and characteristics of the Earth's atmospheric layers (대기권의 수직 구조)?

A.In the stratosphere (성층권), temperature continuously decreases with altitude because atmospheric density drops exponentially toward the mesopause.

B.The mesosphere (중간권) exhibits a strong thermal inversion layer due to intense absorption of solar ultraviolet radiation by high-density diatomic nitrogen.

C.The thermosphere (열권) maintains a constant uniform temperature of -80°C because convective air mixing rapidly dissipates all solar radiation.

D.In the troposphere (대류권), air temperature decreases with altitude at an average lapse rate of approximately 6.5°C/km due to decreasing terrestrial radiation.

Explanation: In the troposphere (대류권, surface to ~11 km), temperature decreases with height at an average environmental lapse rate of about 6.5°C/km because the primary heat source is longwave terrestrial radiation emitted from the Earth's surface. In contrast, temperature increases with altitude in the stratosphere (성층권) due to ozone (O3) absorbing solar ultraviolet radiation.

2When comparing the dry adiabatic lapse rate (건조단열감률, Γd ≈ 0.98°C/100m) with the ambient environmental lapse rate (기온감률, -dT/dz = γ), under which condition is the atmospheric boundary layer classified as unstable (불안정 / 과단열)?

A.γ > Γd (Superadiabatic lapse rate: environmental temperature drops faster than 0.98°C per 100 m).

B.γ = Γd (Neutral lapse rate: environmental lapse rate exactly equals the dry adiabatic lapse rate).

C.0 < γ < Γd (Subadiabatic lapse rate: environmental temperature drops slower than the adiabatic rate).

D.γ < 0 (Inversion layer: temperature increases with increasing altitude).

Explanation: When the environmental lapse rate exceeds the dry adiabatic lapse rate (γ > Γd, approximately > 1.0°C/100m), an air parcel displaced upward cools more slowly than the surrounding ambient air, becoming warmer and less dense than its surroundings, which accelerates vertical convection. This state is defined as superadiabatic and thermodynamically unstable (불안정 대기).

3Which of the following statements correctly distinguishes a radiation inversion (복사역전 / 접지역전) from a subsidence inversion (침강역전 / 고층역전)?

A.A radiation inversion forms at the ground surface on clear, calm wind nights due to radiative cooling, whereas a subsidence inversion forms aloft within high-pressure anticyclones as descending air heats adiabatically.

B.A radiation inversion is an upper-air inversion created by advancing cold fronts, whereas a subsidence inversion is strictly a ground-level phenomenon caused by evaporative cooling over water bodies.

C.A subsidence inversion is broken down immediately at daybreak by solar radiation, whereas a radiation inversion typically persists unbroken for multiple weeks across synoptic scales.

D.Both radiation and subsidence inversions foster intense vertical turbulence that rapidly flushes surface air contaminants into the upper stratosphere.

Explanation: A radiation inversion (복사역전) is a surface inversion formed when the ground surface cools rapidly via longwave radiative heat loss during clear, windless winter nights; it typically dissolves within hours after sunrise as solar heating warms the ground. A subsidence inversion (침강역전) is an elevated upper-air inversion formed when a large mass of sinking air in a stagnant high-pressure anticyclone is compressed and warmed adiabatically at its base, creating an extensive lid over hundreds of square kilometers.

4Under which meteorological vertical stability profile does the highly hazardous fumigation plume (훈연형 연기) pattern occur?

A.A superadiabatic, highly unstable lapse rate exists both above and below the stack height throughout an entire clear summer afternoon.

B.An elevated inversion layer remains above the stack top while solar morning insolation establishes an unstable, convective superadiabatic layer beneath stack height.

C.An isothermal or strong surface inversion layer extends well above the stack height, suppressing all vertical and horizontal motion.

D.A surface inversion exists below stack height while an unstable superadiabatic lapse rate prevails above stack height.

Explanation: Fumigation (훈연형) occurs in the morning when night-formed surface radiation inversion is eroded from the ground upward by solar heating. An unstable convective mixing layer develops from the ground up to the stack height, while a stable inversion lid remains intact above the stack. Effluent cannot disperse upward and is rapidly mixed downward toward the ground, causing extremely high ground-level pollutant concentrations.

5Using the steady-state Gaussian plume dispersion equation (가우시안 플룸 모델), calculate the ground-level centerline pollutant concentration C(x, 0, 0) in mg/m³ for an industrial emission source given the following parameters: - Emission rate (Q): 100 g/s - Effective stack height (H): 50 m - Horizontal dispersion parameter (σy): 70 m - Vertical dispersion parameter (σz): 50 m - Mean horizontal wind speed at stack height (u): 4.0 m/s (Assume steady wind, flat terrain, and perfect reflection at the ground. Note: exp(-0.5) ≈ 0.6065, π ≈ 3.1416).

A.Approximately 0.45 mg/m³

B.Approximately 1.38 mg/m³

C.Approximately 4.25 mg/m³

D.Approximately 8.62 mg/m³

Explanation: The ground-level centerline concentration equation from a elevated point source is: C(x, 0, 0) = [Q / (π * u * σy * σz)] * exp[-H² / (2 * σz²)]. Plugging in the parameters: Denominator = π * 4.0 * 70 * 50 = 3.1416 * 14000 = 43,982.4 m³/s. Pre-exponential factor = 100 g/s / 43,982.4 m³/s = 0.0022736 g/m³ = 2.2736 mg/m³. Exponential term: exp[-50² / (2 * 50²)] = exp(-1/2) = exp(-0.5) ≈ 0.6065. C(x, 0, 0) = 2.2736 mg/m³ * 0.6065 ≈ 1.379 mg/m³ ≈ 1.38 mg/m³.

6By international convention and atmospheric chemistry standards, precipitation is classified as acid rain (산성비) when its pH drops below which benchmark threshold, and what is the thermodynamic basis for this value?

A.pH 4.0; aquatic ecosystems experience complete biological mortality only when water bodies acidify below pH 4.0.

B.pH 5.6; pure atmospheric water in chemical equilibrium with ambient background carbon dioxide (~400 ppm) dissolves to form weak carbonic acid (H2CO3).

C.pH 6.5; sulfurous smog in unpolluted maritime atmospheres naturally buffers rainfall to pH 6.5.

D.pH 7.0; any precipitation having a hydronium ion concentration greater than neutral distilled water at 25°C is considered legally acidic.

Explanation: Unpolluted atmospheric moisture naturally dissolves ambient background carbon dioxide (CO2 ≈ 400-420 ppm). Dissolved CO2 hydrolyzes into carbonic acid (CO2(aq) + H2O <-> H2CO3 <-> H+ + HCO3-), establishing a chemical equilibrium that yields an aqueous pH of approximately 5.6 at 25°C. Therefore, precipitation with a pH below 5.6 indicates the presence of strong anthropogenic acids (primarily H2SO4 and HNO3) and is classified as acid rain.

7Which of the following pairs correctly contrasts the classic 1952 London Smog (런던 스모그) with the Los Angeles Photochemical Smog (로스앤젤레스 스모그)?

A.London smog was a reducing smog driven by coal combustion, SO2, and particulates under a winter radiation inversion; LA smog is an oxidizing smog driven by auto exhaust, NOx, and VOCs under summer solar radiation.

B.London smog occurred on hot sunny summer afternoons characterized by high ozone levels; LA smog occurred during cold foggy winter mornings characterized by massive sulfuric acid accumulation.

C.London smog was predominantly photochemical and produced eye-irritating PAN; LA smog was an industrial smoke event caused exclusively by high-sulfur bituminous coal power stations.

D.London smog occurred under strong frontal cyclonic storm winds that rapidly dispersed pollutants; LA smog occurred under stagnant Arctic maritime air masses in mid-winter.

Explanation: The Great Smog of London (December 1952) was a classic reducing (sulfurous) smog: heavy burning of sulfurous coal produced high concentrations of SO2 and soot particles trapped under a surface radiation inversion and dense cold fog in the early morning. In contrast, the Los Angeles smog (1940s-1950s) was an oxidizing (photochemical) smog: extensive automobile emissions of NOx and reactive hydrocarbons reacted under intense summer solar ultraviolet radiation and subsidence inversions to form ozone, aldehydes, and PAN.

8Regarding greenhouse gases (온실가스) and their 100-year Global Warming Potentials (지구온난화지수, GWP100), which of the following statements is scientifically accurate?

A.Carbon dioxide (CO2) has the highest individual molar radiative forcing of all greenhouse gases, with a GWP100 exceeding that of nitrous oxide (N2O) and all halocarbons.

B.Methane (CH4) has an atmospheric lifetime of approximately 1,000 years and a 100-year GWP lower than that of carbon dioxide.

C.Water vapor (H2O) is legally classified under the Kyoto Protocol and Clean Air Conservation Act as an industrial fluorinated GHG subject to cap-and-trade quotas.

D.Sulfur hexafluoride (SF6) possesses an exceptionally high GWP100 (exceeding 23,000) and an atmospheric lifetime of thousands of years, whereas CO2 serves as the baseline reference gas (GWP = 1).

Explanation: By international convention (IPCC), carbon dioxide (CO2) is the reference greenhouse gas with a defined GWP of 1. Sulfur hexafluoride (SF6), widely used as a dielectric gas in electrical switchgear, exhibits an exceptionally potent infrared absorption cross-section and chemical inertness, giving it an atmospheric lifetime of ~3,200 years and a 100-year GWP of approximately 23,500 to 25,200.

9In micrometeorology, the gradient Richardson number (리차드슨 수, Ri) is defined as: Ri = (g / T) * (dθ/dz) / (du/dz)² Which of the following correctly interprets the dynamic stability of the atmosphere when Ri > 0.25 (critical Richardson number, Ric)?

A.Buoyant thermal convection completely overwhelms wind shear, producing extreme convective turbulence and intense vertical mixing.

B.Turbulent mechanical shear is completely suppressed by strong buoyant damping, causing the flow to become dynamically stable and laminar.

C.The atmosphere enters a state of neutral equilibrium where momentum flux exactly balances heat flux with no dampening.

D.Wind shear reaches infinity, triggering Kelvin-Helmholtz billows that generate violent localized gustiness.

Explanation: The Richardson number represents the dimensionless ratio of buoyant suppression/generation of turbulence to mechanical production of turbulence by wind shear. When the gradient Richardson number exceeds the critical value (Ri > 0.25), the stabilizing buoyant forces (positive potential temperature gradient dθ/dz > 0) are strong enough to suppress any turbulence generated by vertical wind shear (du/dz). Under this condition, existing turbulence decays and the airflow becomes dynamically stable and predominantly laminar.

10According to Koschmieder's formula for atmospheric visual range (시정 거리, Lv = 3.912 / bext), which light-scattering regime is primarily responsible for atmospheric haze and visibility impairment caused by fine aerosols (0.1–1.0 µm)?

A.Rayleigh scattering (레일리 산란), because aerosol particles are vastly smaller than 0.001 times the wavelength of visible light.

B.Compton scattering, because visible photons lose energy through collisions with relativistic free electrons in the lower troposphere.

C.Geometric optical refraction, because light rays pass directly through microscopic glass beads without any angular diffraction.

D.Mie scattering (미 산란), because the aerosol particle diameters are roughly comparable to the wavelengths of visible light (0.4–0.7 µm).

Explanation: Under Koschmieder's law, visual range is inversely proportional to the atmospheric light extinction coefficient (bext), which is dominated by particle scattering (bsp). Fine aerosols with diameters between 0.1 µm and 1.0 µm have sizes on the exact same order as the wavelength of visible light (0.4–0.7 µm), where Mie scattering operates at peak scattering efficiency per unit aerosol mass, causing severe visibility reduction and atmospheric haze.

About the Engineer Air Pollution Environmental Exam

The Engineer Air Pollution Environmental (대기환경기사) qualification is South Korea's Engineer-grade national technical credential for air quality specialists and plant environmental managers. Established under the National Technical Qualifications Act (국가기술자격법) and administered by HRD Korea (한국산업인력공단) under the Ministry of Environment (환경부), it is the qualification that Table 10 of the Enforcement Decree of the Clean Air Conservation Act requires a Class 1 business site to appoint as its Environmental Engineer (대기환경기술인). From 1 January 2026 the written paper covers four subjects rather than five, the former 대기오염개론 and 대기환경관계법규 papers having been merged into 대기환경관리. This practice material is an independent English-language MCQ study adaptation by OpenExamPrep, not an official translation or format simulation. It provides 80 questions that keep the official Korean engineering and statutory terms in parentheses — such as (대기환경관리), (연소공학), (대기오염방지기술), (대기오염공정시험기준), (등속흡인) and (전기집진기).

Exam sponsor: Human Resources Development Service of Korea (한국산업인력공단 / Q-Net) under the Ministry of Environment (환경부). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Assessment

Written examination (필기): four 20-item subjects sat together over 120 minutes, 30 minutes per subject — Subject 1: Air Environment Management (대기환경관리, 20 items); Subject 2: Combustion Engineering (연소공학, 20 items); Subject 3: Air Pollution Prevention Technology (대기오염방지기술, 20 items); Subject 4: Standard Test Methods for Air Pollution (대기오염공정시험기준, 20 items). Candidates must score at least 40 points in every subject to avoid subject failure (과락) and at least 60 points overall. Practical examination (실기): 대기오염관리 실무, a written-answer paper of about 3 hours marked out of 100, with 60 points required to pass.

Time Limit

120 minutes (2 hours) for the written examination; about 3 hours for the written-answer practical

Passing Score

At least 40 points in each subject and an overall average of at least 60 points (60% aggregate)

Exam / Certification Fees

KRW 19,400 (written examination / 필기시험); KRW 22,600 (practical examination / 실기시험)

Exam sponsor website

Reported exam pass rate: Approximately 30%–40% for the written examination; 35%–45% for the practical examination. Due to rigorous multi-variable combustion stoichiometry, fluid mechanics of dust collection equipment, instrumental analytical chemistry, and legal thresholds under the Clean Air Conservation Act, the written exam maintains a competitive annual pass rate around 35%. This describes exam candidates, not OpenExamPrep users or results from using our resources. Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Official sources

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

25%

Air Environment Management (대기환경관리)

Atmospheric structure and vertical temperature profiles, dry and wet adiabatic lapse rates, stability classes and inversions (radiation, subsidence, frontal), plume behaviour types, Gaussian plume dispersion and Holland plume rise, effective stack height, photochemical oxidants and acid deposition, greenhouse gases and global warming potentials, and the statutory framework of the Clean Air Conservation Act (대기환경보전법) — business-site classification, environmental engineer appointment standards, emission surcharges, ambient air quality standards and the ozone and particulate alert systems. From 1 January 2026 this subject merges the former 대기오염개론 and 대기환경관계법규 papers.

25%

Combustion Engineering (연소공학)

Solid, liquid and gaseous fuel properties, proximate and ultimate coal analysis, stoichiometric oxygen and theoretical air (Ao), excess air ratio and air-fuel ratio, theoretical and actual dry/wet flue gas volumes (God, Gow, Gd, Gw), higher and lower heating values, flammability limits and Le Chatelier's rule, burner types, adiabatic flame temperature, formation mechanisms of Thermal, Prompt and Fuel NOx, SOx and acid dew point corrosion, dioxin de novo synthesis, staged combustion and fluidised bed combustion.

25%

Air Pollution Prevention Technology (대기오염방지기술)

Gravity settling chambers and Stokes' law, cyclones and cut diameter, fabric filters (filtration velocity, cloth area, pulse-jet cleaning, blinding), electrostatic precipitators (Deutsch-Anderson equation, migration velocity, dust resistivity, back corona), venturi and wet scrubbers, Henry's law and two-film absorption theory, packed tower hydraulics and flooding, physical versus chemical adsorption, Freundlich isotherms and breakthrough curves, wet limestone-gypsum flue gas desulfurisation, selective catalytic reduction and ammonium bisulfate fouling, and biofiltration.

25%

Standard Test Methods for Air Pollution (대기오염공정시험기준)

Sampling port siting and traverse point selection for circular and rectangular stacks, Pitot tube velocity measurement, isokinetic sampling and nozzle sizing, flue gas moisture determination, oxygen correction of measured concentrations, instrumental methods (NDIR, chemiluminescence, gas chromatography detectors, HPLC with 2,4-DNPH, atomic absorption and cold-vapour mercury, ICP-OES), wet chemical methods for SOx, NOx and fluorides, odour dilution olfactometry, and CleanSYS continuous emission monitoring drift tolerances.

Preparing for the Engineer Air Pollution Environmental Exam

What You Need to Know

Passing score: At least 40 points in each subject and an overall average of at least 60 points (60% aggregate)
Assessment: Written examination (필기): four 20-item subjects sat together over 120 minutes, 30 minutes per subject — Subject 1: Air Environment Management (대기환경관리, 20 items); Subject 2: Combustion Engineering (연소공학, 20 items); Subject 3: Air Pollution Prevention Technology (대기오염방지기술, 20 items); Subject 4: Standard Test Methods for Air Pollution (대기오염공정시험기준, 20 items). Candidates must score at least 40 points in every subject to avoid subject failure (과락) and at least 60 points overall. Practical examination (실기): 대기오염관리 실무, a written-answer paper of about 3 hours marked out of 100, with 60 points required to pass.
Time limit: 120 minutes (2 hours) for the written examination; about 3 hours for the written-answer practical
Exam / certification fees: KRW 19,400 (written examination / 필기시험); KRW 22,600 (practical examination / 실기시험) Official sources

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Engineer Air Pollution Environmental: Suggested Study Strategy

1Work the combustion arithmetic until it is automatic (연소공학): theoretical oxygen and theoretical air (Ao = 8.89C + 26.7(H − O/8) + 3.33S), excess air ratio from flue gas oxygen (m = 21/(21 − O2)), and theoretical and actual dry/wet flue gas volumes (God, Gow, Gd, Gw). Numerical items dominate this subject.

2Treat 대기환경관리 as two halves (대기환경관리): the dispersion half — lapse rates, stability, inversions, plume types, the Gaussian equation and Holland plume rise — and the statutory half — business-site classes, engineer appointment standards, emission surcharges, ambient standards and alert thresholds. The 2026 merge means both halves are examined inside one 20-item subject.

3Learn the governing equation behind each abatement device (대기오염방지기술): Stokes' settling velocity, cyclone cut diameter, cloth area from filtration velocity, the Deutsch-Anderson equation, Henry's law and the two-film model, and the Freundlich isotherm. Most items are solved by picking the right equation rather than by recall.

4Drill sampling geometry and isokinetics (대기오염공정시험기준): traverse points are set by inside diameter for circular stacks and by cross-sectional area for rectangular ones, the 8D/2D port-siting rule, Pitot tube velocity, nozzle sizing for isokinetic suction, and the oxygen-correction formula.

5Memorise the statutory numbers that recur every sitting: business-site tonnages (Class 1 ≥ 80 t, Class 2 20–80 t, Class 3 10–20 t, Class 4 2–10 t, Class 5 < 2 t), basic emission surcharge pollutants (SOx and dust), self-measurement record retention of three years, and the PM10 / PM2.5 annual standards of 50 and 15 µg/m³.

Frequently Asked Questions

What is the Engineer Air Pollution Environmental (대기환경기사) qualification?

It is an Engineer-grade national technical qualification established under South Korea's National Technical Qualifications Act (국가기술자격법) and administered by HRD Korea (한국산업인력공단 / Q-Net) under the Ministry of Environment (환경부). Holders design, operate and inspect industrial air pollution prevention facilities, and the qualification satisfies the statutory appointment of a designated Environmental Engineer (대기환경기술인) at a Class 1 business site.

What is the structure, timing and passing standard of the written examination?

Since 1 January 2026 the written examination has been 80 four-option multiple-choice questions across 4 subjects, 20 questions each, in a single 120-minute CBT session: (1) Air Environment Management (대기환경관리), (2) Combustion Engineering (연소공학), (3) Air Pollution Prevention Technology (대기오염방지기술), and (4) Standard Test Methods for Air Pollution (대기오염공정시험기준). Candidates must score at least 40 points in every subject to avoid 과락 and at least 60 points overall.

What changed in the 2026 examination standard?

Under the amended 출제기준 effective 1 January 2026, the former Subject 1 (대기오염개론) and Subject 5 (대기환경관계법규) were merged into a single subject called 대기환경관리, reducing the written paper from five subjects and 100 questions to four subjects and 80 questions, and the session from 150 to 120 minutes. The practical paper was renamed from 대기오염방지 실무 to 대기오염관리 실무.

What fees apply?

The written examination fee is KRW 19,400. After passing the written examination the practical examination (실기시험, 대기오염관리 실무) fee is KRW 22,600.

How long does a written pass stay valid?

A written examination pass is valid for two years from the date the written result is announced. During that period the candidate is exempt from the written paper and may register directly for the practical examination.

Which technical qualification must each class of business site appoint?

Under Table 10 of the Enforcement Decree of the Clean Air Conservation Act, a Class 1 site (80 t/yr or more of dust, SOx and NOx) must appoint at least one holder of 대기환경기사 or higher; a Class 2 site (20 to under 80 t/yr) at least one holder of 대기환경산업기사 or higher; a Class 3 site (10 to under 20 t/yr) 대기환경산업기사 or higher, 환경기능사, or a person with three or more years of air-field environmental work; Class 4 and Class 5 sites may nominate an employee working on the emission and prevention facilities.

Is this practice bank an official examination paper?

No. The official examination is administered in Korean. This bank is an independent English-language MCQ study adaptation by OpenExamPrep — not an official translation, a format simulation, or a substitute for the written-answer practical examination.