ENV627 Fundamentals of Air Quality 2023 PDF

PART 1: Introduction to Air Pollution Causes & Effects of Air Pollution Learning Objectives • To gain insights into the science of air pollution • To identify key air pollutants and their sources • To understand the effects of air pollution on health and the environment. Definition of Air Pollut...

PART 1: Introduction to Air Pollution Causes & Effects of Air Pollution Learning Objectives • To gain insights into the science of air pollution • To identify key air pollutants and their sources • To understand the effects of air pollution on health and the environment. Definition of Air Pollution Air pollution is the presence in the air of substances put there by the acts of human activity in concentrations sufficient to interfere with: q q q q Health Comfort Safety Full use and enjoyment of property The Great London Smog, 1952 The Great London Smog, 1952 What is in the air? So where are the pollutants? What compounds do we normally associate with air pollution? o Why are they not prominent in the general composition of the atmosphere? o What types of pollutant are there and where do they come from? o What effects do they have? o Can you identify 10 common pollutants, identify where they come from and explain why they don’t appear in the general composition of the atmosphere? Pollutants… o Primary pollutants are emitted directly from a source e.g. volatile organic compounds (VOCs), nitrogen oxides (NO & NO2), sulphur dioxide (SO2), particulate matter (PM), carbon monoxide (CO), carbon dioxide (CO2), heavy metals (Pb, Cd, Cu), ammonia (NH3), polycyclic aromatic hydrocarbons (PAHs), benzene and 1,3-butadiene o Secondary pollutants form when other pollutants (i.e. primary pollutants) react in the atmosphere e.g. Ozone (O3), NO2, acid rain, PM, peroxyacetyl nitrate (PAN) Levels of Pollutants Data obtained from: DoE Dhaka Farmgate Site Back to Smog… Sources of Pollutants • Natural sources • Anthropogenic (or manmade) sources Natural Sources… o o o o o Volcanoes: have released particulate matter and gases into the atmosphere for millions of years. Lightening strikes form nitrogen oxides as well as causing forest fires contributing to gases and particles. Organic matter decay in swamps Wind storms circulating dust Trees and other vegetation contribute large amounts of pollen and spores to the atmosphere. Anthropogenic Sources Mobile sources include most forms of transportation such as cars, lorries and airplanes. o Stationary sources consist of non-moving sources such as power plants and industrial facilities. These are split into: o Point Sources: a source at a fixed point, such as a smokestack or storage tank. o Area Sources: a series of small sources that together can affect air quality in a region. o Top ten… The main air pollutants as identified by UK, USEPA: Sulphur dioxide o Nitrogen oxides o Carbon monoxide o Ozone o Particulate matter o Lead o Benzene o 1,3- butadiene o Polycyclic aromatic hydrocarbons o Ammonia o Sulphur dioxide (SO2) Anthropogenic sources Natural sources Removal Sulphur in Fuels ~ 80% Industrial Processes ~ 20% Volcanoes Biological Oxidation to SO4 over 1 to 4 days Potential damage to ecosystems at high levels, including degradation of chlorophyll, reduced photosynthesis, raised respiration rates and changes in protein metabolism. Deposition of SO2 derived pollution contribute to acidification of soils and waters and subsequent loss of biodiversity. Nitrogen oxides (NO and NO2) Anthropogenic sources Natural sources Removal High Temperature Combustion: Cars, lorries etc ~ 50% Fuel Combustion ~ 45% Biogenics in soil Lightning Forest Fires Oxidation to HNO3 over 2 to 5 days High levels of NOX can have an adverse effect on vegetation, including leaf or needle damage & reduced growth. Deposition of NOX derived pollutants contribute to acidification and/or eutrophication of sensitive habitats leading to loss of biodiversity. Carbon monoxide (CO) Anthropogenic sources Natural sources Removal Automobiles ~ 75 % Agricultural ~ 10 % Forest Fires Photochemical reactions with OH radical over 1 to 3 months Ozone Anthropogenic sources Natural sources Removal Secondary pollutant produced by VOCs, NOx & sunlight. - Transportation - 55% - Industry - 15% - Organic Solvents - 10% Plants & Trees - Photolysis to, and subsequent reactions, with OH - Other chemical reactions - Deposition Ground level ozone can also cause damage to many plant species leading to loss of yield and quality of crops, damage to forests and impacts on biodiversity. Ozone in the Atmosphere Typical O3 mixing ratios: v Boundary Layer 30 - 50 ppb v Stratosphere 3 - 10 ppm Particulate Matter Anthropogenic sources Natural sources Removal - Fuel combustion - Industrial processes - Forest Fires - Volcanoes - Sea-spray - Dust - Vegetation Dry & wet deposition Over weeks in some cases - increased respiratory symptoms - decreased lung function - aggravated asthma - development of chronic bronchitis - irregular heartbeat - nonfatal heart attacks - premature death in people with heart or lung disease. - Reduced visibility (haze) - Increased acidity of lakes and streams - Nutrient balance changes in coastal waters and river basins - Reduced levels of nutrients in soil - Damage to forests and crops - Reduced diversity in ecosystems - Damage to stone and other materials Lead Anthropogenic sources Natural sources Removal - Ore and metal processing - Combustion of coal Sea Salt Wet deposition over ~ 3 days Exposure to high levels in air may result in toxic biochemical effects which have adverse effects on the kidneys, gastrointestinal tract, the joints and reproductive systems, and acute or chronic damage to the nervous system. Affects intellectual development in young children. Benzene http://naei.defra.gov.uk/ v Benzene is a recognized human carcinogen that attacks the Genetic material and, as such, no absolutely safe level can be specified in ambient air. v Studies on workers exposed to high levels have shown an Excessive risk of leukemia. Polycyclic aromatic hydrocarbons (PAHs) http://naei.defra.gov.uk/ v Studies of occupational exposure to PAHs have shown an increased incidence of tumours of the lung, skin, and possibly bladder and other sites. v Lung cancer is most obviously linked to exposure to PAHs through inhaled air. Benzo(a)pyrene http://naei.defra.gov.uk/ Ammonia v Ammonia can lead to damage of terrestrial and aquatic ecosystems through deposition of eutrophying and acidifying pollutants. v It is a precursor to secondary PM and therefore contributes to the ill-health effects caused by PM10 and PM2.5 Ammonia http://naei.defra.gov.uk/ Sulphur Dioxide http://naei.defra.gov.uk/ Nitrogen Oxides http://naei.defra.gov.uk/ PM2.5 http://naei.defra.gov.uk/ Health Summary What is PM2.5 comprised of? • ammonium nitrate • ammonium sulphate • organic matter • primary (emitted) • secondary (formed in the atmosphere) • elemental carbon • soil and dust • trace metals • sea salt SECONDARY INORGANIC PARTICLES • Sulphur dioxide oxidation leads to sulphuric acid formation, which reacts irreversibly with ammonia SO2 + oxidant H2SO4 + 2NH3 (NH4)2SO4 • Nitrogen dioxide oxidation leads to nitric acid formation, which reacts reversibly with ammonia NO2 + oxidant HNO3 HNO3 + NH3 ⇋ NH4NO3 • A reduction in ammonia emissions would be a highly costeffective means of reducing particulate nitrate • Sulphate and nitrate concentrations are decreasing slowly, but not linearly (i.e. in proportion) with emissions of SO2 and NOx SECONDARY ORGANIC PARTICLES • Volatile organic compounds (VOC) are oxidised in the atmosphere. Many of the products are less volatile and condense into the particles • For example: Hydrocarbon aldehyde carboxylic acid • A huge number of VOC, including both anthropogenic and natural compounds oxidise in the atmosphere to form secondary organic aerosol (SOA). • Key precursors of SOA are - isoprene and a-pinene – emitted by plants - alkanes – used as solvents, and present in motor fuels - aromatic compounds – present in solvents, fuels, etc Importance of size… PM10 = particles < 10 µm in diameter PM2.5 (or fine particles) = particles < 2.5 µm in diameter Course particles (PM2.5-10) = PM10 – PM2.5 Ultrafine (or nanoparticles) = particles < 0.1 µm in diameter Size of airborne particles… Size range of airborne particles, showing the health related ultrafine, PM2.5 and PM10 fractions and the typical size range of some major components On a linear scale… Ash Formation from Coal v Ash particles produced in coal combustion have long been controlled by cleaning the flue gases with electrostatic precipitators. Most of the mass of particulate matter is removed by such devices, so ash received relatively little attention as an air pollutant and the concentrations of many toxic species in the ash particles increased with decreasing particle size. Particle removal techniques are less effective for small (i.e., submicron) particles than for larger particles. Thus, even though the total mass of particulate matter in the flue gases may be reduced substantially by electrostatic precipitation or another system, the particles that do escape collection are those that contain disproportionately high concentrations of toxic substances. v Coal is a complex, heterogeneous, and variable substance containing, in addition to the fossilized carbonaceous material, dispersed mineral inclusions. The sizes of these inclusions vary from one coal to another and also depend on the way the coal is prepared. The mean diameter of the mineral inclusions is typically about 1 um. These inclusions, consisting of aluminosilicates with pyrites, calcites, and magnesites in various proportions, eventually form ash particles as the carbon bums out. The ash particles that are entrained in the combustion gases are called fly ash. Ash Formation from Coal Sec. 6.1 Ash 363 Devolatilization Char combustion fusion Char :< :..:. J .".." ':?::.'.. >.... Vaporization . .. : '.' (Si0 2 , . '.: . . . .' species nucleation MgO, FeO, A1 2 0 3 , etc.) , Volatile species condensation and surface enrichment (No, K, Cd, As, Pb, etc,) '\oagUlatlon and fUSion -, .' ..... . '. :::, •.•• ,'.' . . .... , " ' ,. .. ' Coagulation and 0. ' .. " , .. "'" .. ' ' \ • .' • : . .... ... ". • 7 '. ' "... " 0 0,01-0,1 f-Lm , " 0 0 .,," 0 ", t .. .. 0 --"""" , . • 0 0 ...:' : . , ,' •• t .... . , ':' ". t ," 0 0 Char burn out .' "" ' " • 0 , .. ... " ' . 0 00 ., ',:,« " .. : ,:: : ,', . • 4. : •• " ,'. " ' ::' : chain agglomerate ":'" . ;',' formation '.' . .' ... # , .I,. : .. . . s •-." . v ' " " • :.r: c-.., • 10 f-Lm: , . , .. Figure 6.4 Schematic diagram of the processes involved in ash particle fomlation, .. " :1, .:. '. ' , .' \ ' Soot Formation v Carbonaceous particles can also be produced in the combustion of gaseous fuels and from the volatilized components of liquid or solid fuels. The particles formed by this route, known as soot, differ markedly from the char and coke discussed previously. v Most commonly, soot particles are agglomerates of small, roughly spherical particles. While the size and morphology of the clusters can vary widely, the small spheres differ little from one source to another. v They vary in size from 0.005 to 0.2 um but most commonly lie in the size range 0.01 to 0.05 um. The structural similarity between soot particles and the inorganic particles produced from volatilized ash suggests a common origin. v The genesis of soot, however, is much less well understood that that of the inorganic particles due to the extreme complexity of hydrocarbon chemistry in the flame, as well as to the fact that soot particles can bum if exposed to oxygen at high temperatures. Soot Formation Particle Formation in Combustion v Soot particles are not pure carbon. The composition of soot that has been aged in the hightemperature region of the flame is typically CxH, but soot may contain considerably more hydrogen earlier in the flame. Chap. 6 v Furthermore, soot particles adsorb hydrocarbon vapors when the combustion products cool, frequently accumulating large quantities of polycyclic aromatic hydrocarbons. (a) v Soot forms in a flame as the result of a chain of events that begins with pyrolysis and oxidative pyrolysis of the fuel into small molecules, followed by chemical reactions that build up larger molecules that eventually get big enough to become very small particles. v The particles continue to grow through chemical reactions at their surface reaching diameters in the range 0.01 to 0.05 um at which point they begin to coagulate to form chain agglomerates. (b) v The C/H ratio of the small particles is about unity, but as soot ages in the flame it loses hydrogen eventually exiting the flame with a C/H ratio of r of 100 carbon atoms each. The structure within each sheet is similar to that of about 8. hite, but adjacent layers are randomly ordered in a turbostratic structure. The plateFigure 6.10 Transmission electron microscope photographs of soot particles produced in a laminar diffusion flame with acetylene fuel illustrating the agglomerate structure (courtesy of E. Steel, National Bureau of Standards). Fate and transport of particles Effects of ozone on health Mouse Lungs with filtered air After 90 days at 150 ppb Ozone Geographical Scales o GLOBAL: Affects both hemispheres and have some impact upon all locations. o REGIONAL: Affects large geographic areas but not whole hemispheres. o NATIONAL: Affects one or more countries, but not an entire region. o LOCAL: Affects only part of a country. Examples & Effects… AREA POLLUTANT EFFECT Local Nitrogen dioxide Respiratory Diseases Benzene & 1,3-butadiene Cancer Carbon monoxide Heart Disease Particulate matter Heart and Lung Diseases Examples & Effects… AREA POLLUTANT EFFECT Local Nitrogen dioxide Respiratory Diseases Benzene & 1,3-butadiene Cancer Carbon monoxide Heart Disease Particulate matter Heart and Lung Diseases Ozone Crop loss Human lung function Acid rain Forest decline Lake and river fish Nitrogen compounds Loss of biodiversity Eutrophication Regional Examples & Effects… AREA POLLUTANT EFFECT Local Nitrogen dioxide Respiratory Diseases Benzene & 1,3-butadiene Cancer Carbon monoxide Heart Disease Particulate matter Heart and Lung Diseases Ozone Crop loss Human lung function Acid rain Forest decline Lake and river fish Nitrogen compounds Loss of biodiversity Eutrophication Carbon dioxide Global warming Chlorofluorocarbons Ozone depletion Regional Global Summary: Part 1 o POLLUTANTS: Gases and particles that exist in small concentrations but can have a huge impact on health and the environment. o CAUSES: Emissions of primary pollutants from sources such as point (large stacks), mobile (transport), area (vegetation / several small combustion sources in one area) and may be natural or anthropogenic. Summary: Part 2 o EFFECTS: Impacts on health, ecosystems, biodiversity, built environment etc from eutrophication, acidification, ground level ozone and direct emissions of gases and particles. o WHERE: Pollution doesn’t always just affect the place where it is released, can be transported across boundaries. Emission Reductions: Why? Dublin: Demonstration of impact of control measures • Oil crisis in late 1970’s led to programs to encourage use of solid fuels, primarily coal • 1980’s -switch from oil to coal • Dominant source of air pollution in Dublin was smoke from domestic fires Dublin Dublin Deaths 1980-1990 All Cardiovascular Respiratory Others Experience from Dublin: Actions On September 1, 1990, the Irish Government banned the marketing, sale, and distribution of bituminous coals within Dublin County Borough, that is the city of Dublin (Air Pollution Act, 1987). Dublin: Effects of Actions Clancy et al, Lancet 2002 Effect of ban on sale of coal on air pollution in Dublin à 36 µg/m3 BS (-71%) à 11 µg/m3 SO2 (-34%) Effect on mortality à -7% Total Mortality à -13% Cardiovascular à -16% Respiratory à -3%Other PART 2: Basic atmospheric science relevant to air pollution Mixing Ratios (X) Mixing ratios of trace gases are commonly given in parts per million (or billion) Mixing ratio is the fraction of the atmosphere made up of a particular species, relative to the sum of all other species Χ Χ Χ Χ !"#$$"%""& !"'#!#$!("%"))* !"'#!#$"("%"))+ !"'#!#$#$("%"))! p V n c= = = ptot Vtot ntot e.g. H2O = 1-4% → ,%$& %"$-$#.$-$/ → 10,000-40,000 ppmv Note that mixing ratios can either be expressed by volume (generally used for gases) or by mass (used for aerosols). These are NOT equivalent. An additional v or m is used to denote this, e.g. ppmv, and should always be used for clarity. Converting abundance units • The relation of pressure volume and particle number and temperature is governed by the Ideal Gas Law pV = nR g T • We can use this equation to relate mixing ratios with concentrations mass nM C= = volume V • c= p V n = = ptot Vtot ntot Substitute for n using the ideal gas law to relate concentration to temperature and pressure nM pM C= = V RgT • Rearrange and substitute for p in mixing ratio equation CRg T p c= = ptot Mptot Note: These equations all require the quantities to be in SI units: kg, m, s, K, moles, N, Pa Converting abundance units Convert 380 ppmv of CO2 into gm-3 at: a) the surface (1013 hPa) b) at 500 hPa (ca 5 km altitude) Assume Tsurf = 288.2 K T500 = 251.3 K CRg T p c= = ptot Mptot (values based on the International Standard Atmosphere Rg = 8.314 J K-1 mol-1 Molecular weight of O = 16 g mol-1 Molecular weight of C = 12 g mol-1 What do your answers tell you above the relative application of mixing ratios versus concentrations? Photochemical Smog • Photochemical smog is driven by the photochemistry of volatile organic compounds (VOCs) and oxygenated nitrogen species (NOx) contain in exhausts from combustion engines. • Photochemical smog is air saturated with ozone, VOCs peroxy acyl nitrates (PAN) and aerosol particles – it is brown in colour Mexico City Shanghai Industrial Smog Photochemical Smog Baseline + Photochemical tropospheric ozone IPCC Fourth Assessment Report Working Group I Report “The Physical Science Basis“ (Denman et al. 2007). Volatile Organic Compounds (VOCs) • Emitted from natural and anthropogenic sources • Also called Non-Methane Hydrocarbons (NMHCs) Anthropogenic VOCs important for O3 production 1. m- and p-Xylene 2. Ethene 3. Acetaldehyde 4. Toluene 5. Formaldehyde 6. i-Pentane 7. Propene 8. o-Xylene 9. Butane 10.Methylcyclopentane Biogenic VOCs important for O3 production Forests are a major source of reactive trace gases, especially VOCs Hantson et al., Atmospheric Environment, 2017 Tropics - Isoprene Temperate forest - monoterpenes Back to Photochemical Smog Mexico City Mexico City and Smog …a story of success • Reduced vehicle emissions – Replaced old soot emitter cars – Use of low-sulphur fuel – Removed lead from gasoline • Expanded public transport – Low emissions Metrobus System – Hybrid buses – Suburban trains • Used natural gas • Relocated refineries and factories Sinks: Physical and Chemical “Sink”: Mechanism by which pollutants leave the atmosphere • Physical Sinks: – Wet deposition – Dry deposition • Chemical Sinks: – Chemical transformations – Chain terminating reactions – Change of Phase Dry deposition O3, NO2, particles, and some VOCs are deposited to plants and other surfaces Dry deposition of particles Classical Theory predicts 3 modes for particles: Measurements Classical Theory Coarse mode – loss by sedimentation Fine mode – coagulations with large particles Accumulation mode - no dry deposition, but some wet deposition Litschke et al., On the reduction of urban particle concentration by vegetation a review, 2008 Chemical Sinks – the OH Radical Role and importance of OH - Atmospheric “cleaner” – determines the fate of trace constituents - Initiates most VOC removal - Oxidises and chemically converts most air pollutants in the atmosphere (hydrocarbon oxidation) e.g. CH4 - Highly reactive, short lifetime Formation of OH O 3 + hv ® O + O 2 (λ < 310nm) O + H 2 O ® 2OH O + O 2 + M ® O3 Other formation mechanisms HONO photolysis O 3 + Alkene reactions 3 x 106 molec cm-3 J. D. Lee et al., Detailed budget analysis of HONO in central London, 2016 What controls air pollution? What processes control air pollutant concentration in this box? Pollutant Lifetimes (residence times) For a pollutant with a mixing ratio, Q, in and environmental compartment, the budget is: Rate of change = source + chemical production – sink - chemical loss dQ = Fin + P - Fout - L dt In “steady-state” dQ/dt = 0 and Fin+P=Fout+L The average residence time of a pollutant in steady state in an environmental compartment is: Q Q t= = Fin + P Fout + L Calculation Assume an average tropospheric OH concentration of: 3x105 molecules cm-3 The reaction rate of OH with CH4 is: k = 6.4 x 10-15 cm3 molecule-1 s-1 at 298 K (from: iupac.pole-ether.fr) The current atmospheric CH4 mixing ratio is: 1800 ppbv Chemical loss of methane is: L = k * [OH] * [CH4] What is the lifetime of methane in steady state? • Do you need to consider other sinks? • Does your value make sense? What uncertainties might there be in your calculation? • What does this lifetime imply about the area of influence of methane emissions? Pollutant Lifetimes Highly Variable Variable Quasi-Permanent H2O 10 d CH4 10 y O2 5 x103 y CO H2 8 y N2 1x106 y 0.2 y NH3 5 d SO2 4d PM ~ 5 d d= day; y= year He 1x107 y CH4 – variable Longer lived CO-Highly variable shorter lifetime Plots from NOAA: https://www.esrl.noaa.gov/gmd/ccgg/globalview/ Less long-lived species display more spatial and temporal variability NH ž ž The strong seasonal cycle for CO, also applies to anthropogenic VOCs. These gases are important in tropospheric ozone formation SH Helmig et al., 2009, Volatile organic compounds in the global atmosphere, Eos Trans., AGU Meteorology and Weather • Processes that influence air quality – – – – – Sunlight Horizontal dispersion Vertical mixing Transport Clouds and precipitation • Large scale to local scale – – – – – Global: 4,000-20,000 km Synoptic: 400-4,000 km Meso: 10-400 km Urban: 5-50 km Neighbourhood: 50 m – 5 km Vertical Structure of the Atmosphere Stability and Vertical Temperature Height Height Cooler above Warm surface A normal temperature profile gets colder with altitude http://ftp.comet.ucar.edu/ootw/intromet /basic_wx/media/video/unstable_1.mp4 Warm Layer Cool surface A stable temperature profile gets warmer with altitude http://ftp.comet.ucar.edu/ootw/intromet/ba sic_wx/media/video/stable_1.mp4 Stability and Diurnal Temperature Stability and Plume Dispersion The Atmospheric Boundary Layer The lower part of the atmosphere is typically characterised by a wellmixed layer known as the atmospheric boundary layer (ABL), planetary boundary layer (PBL), or mixed layer Lifting is limited by a capping inversion – with the free troposphere above Diurnal variations in the ABL Cooling of surface during sunset – stable nocturnal layer grows from below Heating from radiation on surface during sunrise - convection breaks up stable nocturnal later and entrains air from above Pollutant mixing in the ABL Reservoir of pollutants from previous day trapped above nocturnal inversion – no possibility of dry deposition Vertical mixing suppressed by stable layering. Dry deposition of nocturnal pollutant emissions Sketch the possible evolution of concentration with time for the following cases: 1. Particulates from a local traffic source over 24 hours what if it rained for an hour at midday? 2. NOx emissions from domestic wood burning (for heating and cooking) over the course of a year Who should regulate: Why? Local Government (LA) Local Air Quality Management (LAQM): Local authorities in the UK have statutory duties for managing local air quality under Part IV of the Environment Act 1995 and in Northern Ireland, Part III of the Environment (Northern Ireland) Order 2002. Since December 1997 each local authority in the UK has been carrying out a review and assessment of air quality in their area. This involves measuring air pollution and trying to predict how it will change in the next few years. The aim of the review is to make sure that the national air quality objectives will be achieved throughout the UK by the relevant deadlines. Environment Conservation Rules, 1997 (amended 2021) Air Pollution (Control) Rules, 2022 Bangladesh12748Government Ambient evsjv‡`k †M‡RU, AwZwi³, RyjvB 26, 2022Air Quality Standard !^#$% (#)*+/- +./) 0.10.s. (Ambient Air Quality Standards) [#+#6 \ 0) D(-#+#6 ( ) 0+; #+#6 + 0) D(-#+#6 ( ) ü/t] +./@A-.+ E1 0*1.<n.-Y (CO) 0.10.s. #+ #0#%Z.0/S1#0O.)&# #0#%Z.0/S1#0O.)- A%Y (Pb) #.&+ 0.-*V.Z.0/S1#0O.)U #.+# 0.-*V.Z.0/S1#0O.)- 1.-*o.*X1 Y.-<n.-Y (NO2) %# 0.-*V.Z.0/S1#0O.) ]# 0.-*V.Z.0/S1#0O.)+# 0.-*V.Z.0/S1#0O.)U +# 0.-*V.Z.0/S1#0O.)\+ 0.-*V.Z.0/S1#0O.)U i+ 0.-*V.Z.0/S1#0O.)]# 0.-*V.Z.0/S1#0O.)## 0.-*V.Z.0/S1#0O.)&+# 0.-*V.Z.0/S1#0O.)]# 0.-*V.Z.0/S1#0O.)## 0.-*V.Z.0/S1#0O.)U %## 0.-*V.Z.0/S1#0O.)- +[-[. #(PM10) +[-[.&.+(PM 2.5) `*X.1 (O3) $.%^.) Y.-<n.-Y (SO2) <b.*0.#1D. (NH3) U BQ $0D ] SP. SP. +.#A E&% SP. +.#A E&% SP. +.#A E&% SP. +.#A E&% SP. SP. ] SP. SP. &% SP. +.#A E&% SP. A1.O: * 0- !^#$*% +./ 0.10.s. +#%*! (#)*+/- +./) 0.10.s. (Ambient Air Quality Standards)-A- µc.-*+। (-) BQ0.1 +E$*) 0-+.*)) <#6- <#!V0 -#)*+ 1.। (U) %3b0.s. <#XE! >-*+ :U1 +.#A E- BQ0.1 #16 E.#)! 0.10.s.) 0*ú ;.#-*+ । Bangladesh Government Vehicle Emission Standard evsjv‡`k †M‡RU, AwZwi³, RyjvB 26, 2022 12749 !^#$% & A)*O,:*./, #/G$,1 )*/)*s* [#4#6 \ 0, D9-#4#6 (&) 04= #4#6 ' 0, D9-#4#6 (\) ü/t] । î!/ A)*O,:*/ (F) :*sG4*>G A)*O,I*#Q 04= >*%F* 4*#1#KbF A)*O,:*/ (Passenger Car and Light Commercial Vehicle) A)*O,:*./, 6,/ A$#1 <#=$?ó =, (Reference Mass RW) (#F.%*Z*)) :*sG4*>G M $F% )O,I*#Q >*%F* N1-I RW≤ &+# 4*#1#KbF N1-II &+#<RW A)*O,:*/& ≤ û## N1-III û##<RW #/G$,1 )*/)*s* ( Z*)/#F.#).) (â*%*#/ <R:*WG) F*4 Z/ )./*n*-Y >*-.^*F*4 Z/+ 4[F1* /*-.o*.K./, <n*-Y$k> A9.o*% &.& #Y.K% A9.o*% .# #.+ &.& %.# .# .&+ #.+ #.i +.# .+ #.û 9,G31 9ß#! #Y.K% #Y.K% #.û #.#] û#/&&#/-#$ ($=.g*#6! #.û #.#] '%/ &-#$ .# #. & 04='i/ i'/-#$) .& #. û A)*O,:*./, $.4 Z*— A)*O mK/ [Gross Vehicle Weight (GVW)] &+## #F.%*Z*)। A)*O,:*./, A)*O mK/ &+##<GVW≤ \+###F.%*Z*) >-.% N1 A$#1, #/G$,1 )*/)*s* n.:*Kb >-.4। &:*sG4*>G (o) =*,G A)*O,:*/ (Heavy Duty Vehicle)* -#ò./, 6,/ #/G$,1 )*/)*s* (Z*)/#F.mW*O Ss*) F*4 Z/ >*-.^*F*4 Z/ /*-.o*.K./, 4[F1* )./*n*-Y <n*-Y$k> 9,G31 9ß#! UK AQS 2007: Human Health UK AQS 2007: Human Health UK AQS 2007: Vegetation & Ecosystems