Comparative analysis of real-emitted particulate matter and PM-bound chemicals from residential and automotive sources: A case study in Poland

Ci a ion: Sz amowia -Sala, K.; S yszko, K.; Samek, L.; Kis le , M.; Mache zy´nski, M.; Ryša ý, J.; K pec, K.; Ho ák, J.; Kaspe -Giebl, A.; Goła´s, J. Compa a i e Analysis o Real-Emi ed Pa icula e Ma e and PM-Bound Chemicals om Residen ial and Au omo i e Sou ces: A Case S udy in Poland. Ene gies 2023,16, 6514. h ps://doi.o g/ 10.3390/en16186514 Academic Edi o : Huichao Chen Recei ed: 30 July 2023 Re ised: 2 Sep embe 2023 Accep ed: 5 Sep embe 2023 Published: 9 Sep embe 2023 Copy igh : © 2023 by he au ho s. Licensee MDPI, Basel, Swi ze land. This a icle is an open access a icle dis ibu ed unde he e ms and condi ions o he C ea i e Commons A ibu ion (CC BY) license (h ps:// c ea i ecommons.o g/licenses/by/ 4.0/). ene gies A icle Compa a i e Analysis o Real-Emi ed Pa icula e Ma e and PM-Bound Chemicals om Residen ial and Au omo i e Sou ces: A Case S udy in Poland Ka a zyna Sz amowia -Sala 1, Ka a zyna S yszko 1,* , Lucyna Samek 2, Magdalena Kis le 3, Ma iusz Mache zy´nski 1, Jiˇ íRyša ý4, Kamil K pec 4, Jiˇ íHo ák4, Anne Kaspe -Giebl 3and Janusz Goła´s 1 1Depa men o Coal Chemis y and En i onmen al Sciences, Facul y o Ene gy and Fuels, AGH Uni e si y o K akow, Al. Mickiewicza 30, 30-059 K aków, Poland; [email p o ec ed] (K.S.-S.); [email p o ec ed] (M.M.); [email p o ec ed] (J.G.) 2Facul y o Physics and Applied Compu e Science, AGH Uni e si y o K akow, Al. Mickiewicza 30, 30-059 K aków, Poland; [email p o ec ed] 3Ins i u e o Chemical Technologies and Analy ics, TU Wien, Ge eidema k 9, 1060 Vienna, Aus ia; [email p o ec ed].a (M.K.); anneliese.kaspe [email p o ec ed] (A.K.-G.) 4 Ene gy Resea ch Cen e, Ene gy and En i onmen al Technology Cen e, VSB–Technical Uni e si y o Os a a, 17. Lis opadu 2172/15, Po uba, 708-00 Os a a, Czech Republic; [email p o ec ed] (J.R.); [email p o ec ed] (K.K.); [email p o ec ed] (J.H.) *Co espondence: [email p o ec ed] Abs ac : The awa eness o en i onmen al pollu ion has been con inuously g owing in ecen decades and is cu en ly eaching i s maximum. Eu ope and mos de eloped coun ies a e de e mined o ensu e sa e b ea hing ai o hei ci izens, and he measu es o do so a e s ic e han e e be o e. Combus ion p ocedu es emain he p ima y means o p oducing ene gy and wa m h in Poland. Among he no able cons i uen s o lue gases p oduced as a esul o uel combus ion, solid pa icles (o pa icula e ma e ) hold signi ican p ominence. The pape p esen s he chemical cha ac e isa ion o pa icula e ma e emi ed om s a iona y and au omo i e emission sou ces. S a iona y emission sou ces included he combus ion p ocess o ossil uels (so wood, bi uminous coal, ecopea coal, culm) in domes ic hea ing uni s and he p ocess o combus ion o bi uminous coal in a powe plan . Au omo i e emission sou ces included ligh du y and medium du y ehicles uelled by diesel. Exhaus oxici y es s we e ca ied ou main aining he eal condi ions o PM emission. In all ield measu emen s pa icula e ma e was g a ime ically measu ed and collec ed on qua z o glass ib e il e s. Subsequen ly, he con en o ca bonaceous ac ion, ino ganic ions, and me als and me alloids was analyzed using di e en analy ical echniques. The chemical composi ion o he pa icula e ma e di e ed depending on he emission sou ce. Wi h espec o s a iona y combus ion sou ces, he main ac o s de e mining solid pa icle emission a e ela ed p ima ily o he uel quali y. The du y o ehicles was also a ac o ha in luenced he chemical cha ac e isa ion o he pa icula e ma e emi ed om he engines. Keywo ds: pa icula e ma e ; s a iona y emission sou ces; mobile emission sou ces; combus ion p ocesses; solid uels; liquid uels 1. In oduc ion A mosphe e p o ec ion is one o he mos impo an ac ions unde aken by go e n- men s in he en i e wo ld. Ai pollu ion is he la ges isk ha a ec s bo h en i onmen and human heal h. Pa icula e ma e and PM-bound chemicals inhaled in o he lungs des oy he na u al an ioxida i e ba ie in an o ganism, causing se ious damage o cells, which, in u n, esul in ca dio ascula and in lamma o y diseases and, some imes, e en in p ema u e dea hs [ 1 ]. Despi e many p og ammes owa d cleane a mosphe e se up by he Eu opean Union, le els o pa icula e ma e concen a ion abo e EU s anda ds a e seen Ene gies 2023,16, 6514. h ps://doi.o g/10.3390/en16186514 h ps://www.mdpi.com/jou nal/ene gies Ene gies 2023,16, 6514 2 o 16 ac oss he Old Con inen . Acco ding o da a p esen ed by he Eu opean En i onmen al Agency, Poland ( oge he wi h I aly) is s ill he coun y mos pollu ed by pa icula e ma - e [ 2 ]. This p o es ha mul idisciplina y ac ions owa d dec easing human exposu e o pollu an s and owa d limi a ion hei nega i e impac on ecosys ems a e s ill easonable. In Sou h Poland, esiden ial hea ing and a ic- ela ed emission oge he wi h indus- ial emission, soil emission, and seconda y ino ganic ae osols ha e been epo ed as he main sou ces o a mosphe ic pollu ion [ 3 – 7 ]. Acco ding o he new nomencla u e p oposed by he En i onmen al P o ec ion Agency o he Uni ed S a es, esiden ial hea ing is an example o a non-poin emission sou ce, indus ial emission is a poin emission sou ce, and au omo i e emission belongs o on- oad sou ces. All o hem may be classi ied as low-s ack emission, wha e e s o he emission o ha m ul gases and pa icula e ma e a a le el lowe han 40 m abo e he g ound [ 8 , 9 ]. The low-s ack ela ed pollu an s di ec ly a ec human bodies and heal h. The e o e, i is essen ial o keep hese sou ces con inuously examined and con olled. Pa icula e ma e is an ac i e ca ie o many chemical compounds, bo h o ganic and ino ganic. An ac i e cha ac e o PM is ela ed o he numbe o p ocesses ha a e ongoing in he lue gas duc o in exhaus sys em o engine ca s. Reac ions o nuclea ion, condensa ion, and agglome a ion occu which cause con inuous changes in he chemical composi ion o PM and in size o ae odynamic diame e (AD) o pa icles [ 10 ]. PM 10 and PM 2 . 5 a e classi ica ions o pa icula e ma e by AD ac o , commonly used o measu e ai quali y and po en ial heal h isks. PM 10 e e s o pa icula e ma e wi h a diame e o 10 µ m o smalle . These pa icles a e small enough o be inhaled in o he uppe espi a o y sys em. PM 2 . 5 , on he o he hand, e e s o pa icula e ma e wi h a diame e o 2.5 µ m o smalle . These pa icles a e e en ine and can pene a e deepe in o he espi a o y sys em and lungs and e en en e he bloods eam, posing a g ea e heal h isk [11]. The emission a ios o pa icula e ma e di e depending on uel and s o e o en- gine applied, as well as on he ope a ion condi ions o he combus ion p ocess [ 12 ]. The implemen a ion o exhaus a e ea men sys ems, such as h ee-way ca alys s o diesel oxida ion ca alys s in au omo i e solu ions [ 13 ] and desulphu iza ion plan s and elec o- s a ic p ecipi a o s [ 14 , 15 ] in indus ial u ili ies (i.e., he mal powe plan s) imp o es he quali y o exhaus s eleased o he a mosphe e. Simila ly, many wo ks a ound he wo ld a e conduc ed on exhaus a e ea men sys ems o he pu poses o esiden ial hea ing, i.e., honeycomb P -based ca alys s [16,17]. Rega ding esiden ial hea ing, coal and wood a e usually used o hea and elec ici y gene a ion. Despi e many p og ammes o he ins alla ion o cogene a ion sys ems and eco-design ecommenda ions o he a chi ec u e o domes ic hea ing uni s, due o cu en geopoli ical si ua ion wo ldwide, ossil uels o doub ul quali y a e equen ly used. The usage o such uels in s o es no adap ed o he equi emen s o eco-design di ec i e c ea es he p ocess o combus ion ine icien . This esul s in high emission ac o s o pa icula e ma e and o he PM-bound componen s [12,18]. In Poland, he e exis 19 powe plan s and 23 he mal powe acili ies uelled by bo h bi uminous and ligni e coal as well as biomass. Acco ding o da a om 2022 [ 19 ], he col- lec i e usage o coal o gene a ing hea and elec ici y exceeded 70% in 2021. Fu he mo e, he p ospec s o ansi ioning away om coal as he p edominan p ima y ene gy sou ce a e conside ably ex ensi e [ 20 ]. The combus ion o ossil uels in indus ial p ocesses also gi es ise o pa icula e ma e emissions. The quan i ies o pollu an s emana ing om powe and he mal plan s a e unde cons an su eillance. Indus ial es ablishmen s a e manda ed o cleanse lue gases be o e eleasing hem in o he a mosphe e, achie ed h ough he ins alla ion o pos - ea men sys ems like deni i ica ion, dus ex ac ion, o desul u iza ion uni s. Emissions o igina ing om coal- i ed powe and he mal acili ies aise subs an ial conce ns due o hei capaci y o long-dis ance anspo , ad e se impac on human heal h, isibili y in he a mosphe e, and ha m o ege a ion [21–24]. Au omo i e emissions a e one o he leading sou ces o ai pollu ion wi h a signi ican sha e in o al pa icula e emissions du ing hea ing and non-hea ing seasons, pa icula ly Ene gies 2023,16, 6514 3 o 16 in u ban a eas [ 25 ]. Acco ding o he la es da a p esen ed by he Eu opean Au omobile Manu ac u e s Associa ion (ACEA) in 2020 he e we e mo e han 246 million ehicles in use in he Eu opean Union [ 26 ]. In 2021 app oxima ely 60% o newly egis e ed passenge ehicles we e diesel (20%) and gasoline- uelled (40%) ca s. In u n, new ucks and ans a e mos ly uelled by diesel, sha ing mo e han 96% and 90%, espec i ely, o he o al egis e ed medium- and hea y-du y ehicles. As he sha e o ligh -du y ehicles (LDVs) equipped wi h gasoline engines is highe han ha o LDVs wi h diesel engines, i is ob ious ha cu en esea ch ends in au omo i e b anch a e di ec ed owa d gasoline- uelled and hyb id ca s. Fu he mo e, he Volkswagen emissions scandal, popula ly known as he ‘diesel ga e’, caused, as he main a e ma h, a dec easing popula i y o ligh -du y diesel ehicles among Eu opean d i e s. Howe e , i is ue ha “diesel ga e” un he machine y o imp o emen s in au omo i e legisla ion and diesel pa icula e il e s (DPFs) o elimina e PM emission and selec i e ca aly ic educ ion o elimina e NO x emission was inally implemen ed [ 27 ]. Di icul ies wi h a e bu ning and egene a ion p ocess o DPFs ha e caused hese ca aly ic eac o s o be illegally emo ed om exhaus sys ems e en in 2–3 yea s old ca s. Diesel engines a e cha ac e ised by signi ican ly highe o que han gasoline engines as hey ha e la ge cylinde s and longe s okes. Fu he mo e, diesel engines a e able o ex ac mo e ene gy om uel as hey ope a e a highe comp ession a io [ 28 ]. The e o e, hey a e success ully used in ehicles o medium and hea y du y. Fu he mo e, i is no p edic ed ha he numbe o medium-du y ehicles (MDV) and hea y-du y ehicles (HDV) will dec ease. Fo hese easons, i seems o be adjus able o con inue he examina ions on emission o pollu an s, especially o pa icula e ma e , om diesel- uelled ehicles as well. He e we p esen he chemical cha ac e isa ion o pa icula e ma e gene a ed in combus ion p ocesses o di e en ypes o uel in bo h s a iona y and au omo i e sou ces. Field measu emen s a all emission sou ces we e ca ied ou unde eal condi ions ‘as i is’. Hence, he esul s p o ide aluable in o ma ion on eal exposu e o PM and PM-bound chemicals and allow us o unde s and he na u e o emi ed pollu an s. The inal goal o his wo k was o iden i y cha ac e is ic componen s pe each emission sou ce, o he pu poses o u he wo k conce ning he op imisa ion o mac o ace se ing as a PM sou ce appo ionmen echnique. 2. Ma e ials and Me hods 2.1. Collec ing o Samples o Real-Emi ed Pa icula e Ma e om Di e en Combus ion-Rela ed Sou ces 2.1.1. Sampling o Pa icula e Ma e Emi ed om Residen ial Solid Fuels Combus ion Samples o pa icula e ma e emi ed du ing esiden ial coal combus ion we e g a i- me ically measu ed using a specialised p obe equipped wi h a 47 mm diame e il e holde and a 1 kW lue gas pump. The low o lue gas h ough he p obe was cons an and equal as 2.3 m 3 h −1 . The ac ion o o al suspended pa icles was collec ed. The pa icles we e sampled on qua z ib e il e s (Pall lex ® ) du ing combus ion o ecopea, bi uminous coal, so wood and culm. Once he PM is collec ed, he samples we e hen condi ioned o 48 h o s abilize he mass in condi ions o cons an empe a u e and humidi y. All uels we e combus ed h ee imes in domes ic hea ing uni s (DHU) main aining simila eal condi ions in he combus ion p ocess. Table 1summa ises he pa ame e s cha ac e izing he domes ic hea ing uni s used in expe imen s. 2.1.2. Sampling o Pa icula e Ma e Emi ed om Indus ial Coal Combus ion As an example o indus ial dus samples, he ly ash o he coal combus ion p ocess was aken om he 220 MW powe uni , equipped wi h he OP-650 pul e ised boile (Ra ako, Poland). Samples we e collec ed om a lue gas duc a e he sys ems o selec i e ca aly ic educ ion, elec os a ic p ecipi a ion and we lue gas desul u iza ion. Ash pa icles we e collec ed on 110 mm diame e qua z ib e il e s (Wha man ® QM-A), applying he au oma ic g a ime ic dus measu ing sys em (ZAM K˛e y, Poland) equipped wi h a hea ed p obe and Ene gies 2023,16, 6514 4 o 16 il e ing sys em, d ye , cen al con ol uni , and a egula ed sucking pump (4–10 m 3 h −1 ). The sampling ime was 90 o 120 min. Table 1. The cha ac e isa ion o domes ic hea ing uni s u ilised du ing expe imen s. Fuel Kind DHU Type Sampling Time So wood S o e, nominal powe : 24 kW, e iciency: 83.4% 480–1800 s Culm S eel hea ing boile wi h wa e -cooling wa e , nominal powe 30 kW, e iciency 84% 600 s Ecopea coal Cen al hea ing uni wi h a s o e dedica ed o ecopea coal uelling 600 s Bi uminous coal Cen al hea ing uni a cas i on s o e, nominal powe 18 kW, e iciency 77% 600 s The sampling was ca ied ou acco ding o EN 132841:2001 [ 29 ] and PN-Z-04030- 7:1994 [ 30 ]. S anda ds egula e he me hod o measu emen o dus mass concen a ion, which desc ibes, among o he s, he loca ion demands o measu ing poin s, he size and shape o p obes, and he way o sampling in a speci ic c oss sec ion. Fu he mo e, he sampling and measu emen a e o be pe o med in an isokine ic way, since he lue gas eloci y in he p obe has o be he same as in he lue gas duc . 2.1.3. Sampling o Pa icula e Ma e Emi ed om Diesel-Type Engines Samples o pa icles emi ed om diesel engines we e collec ed basing on he g a ime ic il a ion me hod acco ding o he Regula ion No. 83 o he Economic Commission o Eu ope o he Uni ed Na ions (UN/ECE)–Uni o m p o isions conce ning he app o al o ehicles wi h ega d o he emission o pollu an s acco ding o engine uel equi emen s. The pa icles we e sampled om ligh and medium du y ehicles on glass ib e il e s (Wha mann ® ) o , espec i ely, 47 mm and 70 mm in diame e . The glass ib e il e s we e weigh ed be o e and a e sampling using a Sa o ius weigh wi h an accu acy o 0.0001 mg. The samples we e weigh ed and condi ioned a a weigh ing chambe in cons an empe a u e (22 ± 3 ◦ C) and humidi y (45 ±8%). Pa icle samples emi ed om a medium du y ehicle we e collec ed using he AVL Sma Sample 478 equipped wi h a pa ial lue gas dilu ion unnel on he engine es bed wi h powe b ake. AVL Sma Sample 478 con ains a sampling p obe, cyclone sepa a o , and il e package o a g a ime ic measu emen o solid pa icles. The samples we e collec ed du ing he Eu opean S eady Cycle d i ing es , which is made up o 13 s eps e lec ing a ied le els o engine load. Each es was 1000 s long. Each ime, 54.8 m 3 o lue gas was pumped h ough he glass ib e il e . Pa icles emi ed om a ligh du y ehicle we e sampled on a chassis es bed AVL Zoellne 4WD using he cons an olume sampling sys em wi h a dilu ion unnel and a sys em o g a ime ic measu emen o pa icle emission. In o de o main ain he eal cha ac e o s udies, he emission es s we e conduc ed o pe o m bo h calm u ban d i ing s yle (low speeds wi h an a e age speed a 26 km h -1 , low engine loads and low empe a u e o exhaus s) and mo e agg essi e d i ing s yle in ex a-u ban mode wi h a e age speed o 69 km h−1. 2.2. De e mina ion o he Con en o PM-Bound Chemicals The ba ch o samples o pa icula e ma e samples om esiden ial, indus ial and au omo i e sou ces was analy ically measu ed o he p esence o me als and me alloids, including hea y me als like me cu y (Hg) and a senic (As). The con en o o ganic and elemen al ca bon (OC, EC) and ino ganic ions was also measu ed. Rega ding me als and me alloids he concen a ion o Cl, K, Ca, Ti, V, C , Mn, Fe, Ni, Cu, Zn, B , S , Rb, and Pb was measu ed using a mul i unc ional ene gy dispe si e X- ay luo escence spec ome e acco ding o Samek e al., 2015 and Samek e al., 2016 [ 31 , 32 ]. The QXAS package allowed o quan i a i e analysis acco ding o Vekemans e al., 1994 [33]. To de e mine he concen a ion o PM-bound me cu y, a MA-3000 me cu y au o- ma ic analyze (NIC, Japan), equipped wi h an au o sample , was used. The p inciple Ene gies 2023,16, 6514 5 o 16 o measu emen is based on he mal decomposi ion, gold amalgama ion, and a omic abso p ion. The me hod ollows he ecommenda ions o US EPA 7473 [ 34 ] and ASTM D-6722-01 [ 35 ]. The de ailed p ocedu es o sample ea men we e ou lined in p e ious pape s o Au ho s [14,36]. Ca bonaceous mass ac ion (OC, EC) was de e mined using a he mal op ical me hod (Sunse Lab OC/EC ae osol analyze , Sunse Lab. Inc.) de eloped o a mosphe ic samples, using he qua z.pa empe a u e p o ocol and lase in he ansmission mode. De ails o sample ea men we e desc ibed in a p e ious wo k o Au ho s [ 37 ]. The o al ca bon (TC) in au omo i e pa icula e ma e was de e mined using a ca bon analyze equipped wi h an in a ed adia ion de ec o . The PM sample on a glass ib e il e was bu ned a 1000 ◦ C unde oxygen condi ions. The in a ed senso iden i ied he p oduced CO 2 esul ing om he sample combus ion. The esul s we e hen calcula ed on he basis o he calib a ion cu e p epa ed o he TC mass ange o 5 o 500 µ g. S anda d solu ions we e p epa ed on he basis o a a a ic acid dilu ion [38]. The isoc a ic ion ch oma og aphy (IC) was applied o de e mine he con en o ino - ganic ions as ollows: Na + , K + , Mg 2+ , Ca 2+ , NH 4+ , NO 3− , NO 2− , Cl − , SO 42− . IC analysis was pe o med on an ICS-1100 ins umen (The mo Scien i ic) equipped wi h an AS-DV au osample and ion exchange columns: Ion Pac AS22 (4 × 250 mm) o anions, mobile phase: 4.5 mM Na 2 CO 3 + 1.4 mM NaHCO 3 ; CS16 (5 × 250 mm) o ca ions, mobile phase: 12 mM MSA. A e elec ochemical supp ession (AERS 500 (4 mm) and CERS 500 (4 mm) supp esso s): quan i ica ion was pe o med wi h a conduc i i y de ec o . The injec ion olume was 25 µ L and he low a e was 1.2 mL min −1 . The de ails o me hodology applied was p e iously desc ibed in Sz amowia -Sala e al., 2019 and Pacu a e al., 2022 [12,39]. 3. Resul s and Discussion 3.1. Real-Emission o Pa icula e Ma e om Di e en Combus ion-Rela ed Sou ces Figu e 1p esen s he esul s o g a ime ic analysis and mass econs uc ion o pa ic- ula e ma e emi ed om se en combus ion- ela ed sou ces. WOOD e e s o so wood combus ion in a DHU, CULM– o culm combus ion in a DHU, ECOPEA– o ecopea coal combus ion in a DHU. COAL (In) – o indus ial bi uminous coal combus ion, COAL– o bi uminous coal combus ion in a DHU, LDDV– o low-du y diesel ehicles and MDDV– o medium-du y diesel ehicles. The g a ime ic measu emen s o mass concen a ion o pa icula e ma e eal-emi ed om combus ion- ela ed sou ces demons a ed ha he highes PM emission in lue gas was epo ed o bi uminous coal combus ion in a domes ic hea ing uni and was equal o 464.7 mg m−3 . The emission o PM om combus ion o o he solid uels was se e al imes lowe and complied wi h a dec easing end CULM > WOOD > COAL (In) > ECOPEA e e - ing o concen a ions equal o: 36.7, 20.9, 5.9 and 5.3 mg m −3 , espec i ely. The eco ded mass concen a ion o pa icula e ma e esul ing om indus ial coal combus ion adhe es o he h esholds ou lined in Bes A ailable Techniques conclusions [ 40 ], which es ablish a PM emission ange o 5–50 mg pe no mal m 3 o lue gases. I is clea ha he employed elec os a ic p ecipi a o , u ilized wi hin he powe plan whe e PM samples we e ga he ed, e ec i ely elimina ed he dus p oduced du ing he combus ion p ocess, con ibu ing o he elease o cleane lue gases in o he a mosphe e. The elease o pa icula e ma e om au omo i e sou ces exhibi ed no ably lowe igu es when con as ed wi h he combus ion o esiden ial and indus ial uels. I was eco ded a 592.5 µ g m −3 o low-du y and 101.9 µg m−3 o medium-du y diesel ehicles, which ansla es o emission a es o 0.0003 and 0.0005 g km −1 , espec i ely. These indings align wi h, o ma ginally su pass in he case o MDDV, he PM emission limi s s ipula ed by EURO 6 egula ions, which ha e been es ablished a 0.0045 g km−1. Ene gies 2023,16, 6514 6 o 16 Ene gies 2023, 16, 6514 6 o 17 o pa icula e ma e om au omo i e sou ces exhibi ed no ably lowe igu es when con- as ed wi h he combus ion o esiden ial and indus ial uels. I was eco ded a 592.5 µg m−3 o low-du y and 101.9 µg m−3 o medium-du y diesel ehicles, which ansla es o emission a es o 0.0003 and 0.0005 g km−1, espec i ely. These indings align wi h, o ma - ginally su pass in he case o MDDV, he PM emission limi s s ipula ed by EURO 6 egu- la ions, which ha e been es ablished a 0.0045 g km−1. Figu e 1. Mass concen a ion o eal-emi ed pa icula e ma e om diffe en combus ion- ela ed sou ces (columns—PM mass econs uc ion on he base o PM-bound componen s mass; ▬— he g a ime ically measu ed mass o PM). The analysis o pa icle sizes wi hin pa icula e ma e o igina ing om indus ial combus ion e ealed ha he pa icles con ained 22.9% wi hin he PM2.5 ac ion and 74.9% wi hin he PM10 ac ion [14]. This dis ibu ion migh be in luenced by chemical and physical eac ions occu ing wi hin ume gas duc s, leading o an al e a ion in pa icle dimensions. Simila indings ha e been epo ed by o he esea che s who obse ed ha pa icle size dis ibu ion esul ing om he combus ion o solid uels ypically ollows a bimodal pa e n. In he case o coal combus ion, i gene a es a g ea e p opo ion o coa se pa icles compa ed o ine pa icles [41,42]. Biomass combus ion, con e sely, o en p o- duces a highe quan i y o ine pa icles compa ed o coal [43]. Howe e , ollowing ca - boniza ion o o e ac ion p e ea men , emissions o ine pa icles ypically expe ience a subs an ial educ ion [44]. The size dis ibu ion o pa icles o au omo i e o igin has been al eady widely s udied. I was epo ed ha he majo i y o PM om diesel- uelled ehi- cles is in he nanopa icle ange [45] wi h peak concen a ions wi hin he ange 16–124 nm [46–48]. This ein o ces he ac ha indi iduals a e p ima ily exposed o he ine ac- ions o pa icula e ma e de i ed om combus ion- ela ed sou ces, which p esen g ea e heal h haza ds han hei coa se coun e pa s. The PM samples collec ed du ing he combus ion o a ious uels unde wen de- ailed analy ical ea men , enabling he de e mina ion o he majo chemical cons i uen s Figu e 1. Mass concen a ion o eal-emi ed pa icula e ma e om di e en combus ion- ela ed sou ces (columns—PM mass econs uc ion on he base o PM-bound componen s mass; Ene gies 2023, 16, 6514 6 o 17 o pa icula e ma e om au omo i e sou ces exhibi ed no ably lowe igu es when con- as ed wi h he combus ion o esiden ial and indus ial uels. I was eco ded a 592.5 μg m−3 o low-du y and 101.9 μg m−3 o medium-du y diesel ehicles, which ansla es o emission a es o 0.0003 and 0.0005 g km−1, espec i ely. These indings align wi h, o ma - ginally su pass in he case o MDDV, he PM emission limi s s ipula ed by EURO 6 egu- la ions, which ha e been es ablished a 0.0045 g km−1. Figu e 1. Mass concen a ion o eal-emi ed pa icula e ma e om di e en combus ion- ela ed sou ces (columns—PM mass econs uc ion on he base o PM-bound componen s mass; ▬— he g a ime ically measu ed mass o PM). The analysis o pa icle sizes wi hin pa icula e ma e o igina ing om indus ial combus ion e ealed ha he pa icles con ained 22.9% wi hin he PM2.5 ac ion and 74.9% wi hin he PM10 ac ion [14]. This dis ibu ion migh be in luenced by chemical and physical eac ions occu ing wi hin ume gas duc s, leading o an al e a ion in pa icle dimensions. Simila indings ha e been epo ed by o he esea che s who obse ed ha pa icle size dis ibu ion esul ing om he combus ion o solid uels ypically ollows a bimodal pa e n. In he case o coal combus ion, i gene a es a g ea e p opo ion o coa se pa icles compa ed o ine pa icles [41,42]. Biomass combus ion, con e sely, o en p o- duces a highe quan i y o ine pa icles compa ed o coal [43]. Howe e , ollowing ca - boniza ion o o e ac ion p e ea men , emissions o ine pa icles ypically expe ience a subs an ial educ ion [44]. The size dis ibu ion o pa icles o au omo i e o igin has been al eady widely s udied. I was epo ed ha he majo i y o PM om diesel- uelled ehi- cles is in he nanopa icle ange [45] wi h peak concen a ions wi hin he ange 16–124 nm [46–48]. This ein o ces he ac ha indi iduals a e p ima ily exposed o he ine ac- ions o pa icula e ma e de i ed om combus ion- ela ed sou ces, which p esen g ea e heal h haza ds han hei coa se coun e pa s. The PM samples collec ed du ing he combus ion o a ious uels unde wen de- ailed analy ical ea men , enabling he de e mina ion o he majo chemical cons i uen s — he g a ime ically measu ed mass o PM). The analysis o pa icle sizes wi hin pa icula e ma e o igina ing om indus ial com- bus ion e ealed ha he pa icles con ained 22.9% wi hin he PM 2 . 5 ac ion and 74.9% wi hin he PM 10 ac ion [ 14 ]. This dis ibu ion migh be in luenced by chemical and physical eac- ions occu ing wi hin ume gas duc s, leading o an al e a ion in pa icle dimensions. Simila indings ha e been epo ed by o he esea che s who obse ed ha pa icle size dis ibu ion esul ing om he combus ion o solid uels ypically ollows a bimodal pa e n. In he case o coal combus ion, i gene a es a g ea e p opo ion o coa se pa icles compa ed o ine pa icles [ 41 , 42 ]. Biomass combus ion, con e sely, o en p oduces a highe quan i y o ine pa icles compa ed o coal [ 43 ]. Howe e , ollowing ca boniza ion o o e ac ion p e ea - men , emissions o ine pa icles ypically expe ience a subs an ial educ ion [ 44 ]. The size dis ibu ion o pa icles o au omo i e o igin has been al eady widely s udied. I was epo ed ha he majo i y o PM om diesel- uelled ehicles is in he nanopa icle ange [ 45 ] wi h peak concen a ions wi hin he ange 16–124 nm [ 46 – 48 ]. This ein o ces he ac ha indi iduals a e p ima ily exposed o he ine ac ions o pa icula e ma e de i ed om combus ion- ela ed sou ces, which p esen g ea e heal h haza ds han hei coa se coun e pa s. The PM samples collec ed du ing he combus ion o a ious uels unde wen de ailed analy ical ea men , enabling he de e mina ion o he majo chemical cons i uen s p esen wi hin he pa icula e ma e . Figu e 1illus a es a column cha ha depic s he econs uc- ion o PM mass based on he summa ion o masses a ibu ed o analy ically measu ed PM-associa ed subs ances, which encompass ca bonaceous compounds like o ganic and elemen al ca bon, as well as me als, me alloids, and ino ganic ions, comp ising bo h ca ions and anions. The ca ego y e med “Unde ined” was calcula ed as he di e ence be ween he mass o g a ime ically measu ed PM and he cumula i e mass o PM componen s de e mined analy ically. This ep esen s he po ion o PM ha eluded speci ica ion du ing labo a o y analysis. Fo pa icula e ma e s emming om wood, culm, and coal combus- Ene gies 2023,16, 6514 7 o 16 ion in domes ic hea ing uni s, as well as om diesel- uelled ehicles, he unde ined ac ion did no su pass 15% o he o al PM mass. In con as , wi hin PM gene a ed om indus ial coal combus ion, he unde ined ac ion domina ed, accoun ing o o e 60% o he PM. This can be a ibu ed o he subs an ial con ibu ion o ino ganic PM componen s, o en cha ac e ized by hei hyg oscopic na u e. I is also plausible ha ce ain cons i uen s o PM, such as polycyclic a oma ic hyd oca bons ound in he o ganic ma e , me cu y bound o PM, ni ic ions, ammonium ions, and sulpha e ions, migh ha e e apo a ed du ing sample p epa a ion o ans e . The accu acy and ul ima e ou comes o PM measu emen s can also be in luenced by he chosen me hodology. Nussbaume e al., 2008 [ 49 ] unde sco e ha he selec ion o sampling me hods wa an s me iculous conside a ion o he physical and chemical a ibu es o he PM, he eby minimizing measu emen inaccu acies. To mi iga e e o s, i is ecommended ha pa icula e ma e samples be collec ed h ough p e-dilu ion echniques, which p e en chemical condensa ion ha migh o he wise lead o an o e es ima ion o PM mass concen a ions. Howe e , he au ho s’ in en in his con ex was o cha ac e ize he eal isk posed by exposu e o combus ion- ela ed pa icula e ma e in i s na u al s a e. No ably, o pa icula e ma e o igina ing om combus ion o ecopea coal, he econ- s uc ed mass exceeded he g a ime ically measu ed PM mass. This disc epancy could be a ibu ed o a po en ial o e es ima ion in he analy ical da a due o he ela i ely low masses o he PM samples being analyzed. The de ailed discussion ega ding PM-bound componen s is p esen ed in 3.2–3.4 chap e s. 3.2. PM-Bound Ca bonaceous Compounds The p edominan sha e o pa icula e ma e o igina ing om he combus ion o di e en uels is a ibu ed o ca bonaceous compounds. This is pa icula ly p onounced in he case o so wood combus ion (55.5%), culm combus ion (66.7%), and bi uminous coal combus ion (58.9%) wi hin esiden ial hea ing uni s (Figu e 1). Speci ically, o ganic ca bon cons i u ed 54% o he o al ca bon con en de i ed om so wood, 81% om culm, and a subs an ial 96% om bi uminous coal. Con e sely, o pa icles s emming om he combus ion o ecopea coal, ca bonaceous compounds made up 23% o PM, wi h a cumula i e concen a ion as high as 1230 µ g m −3 . This concen a ion is no ably lowe when compa ed o o al ca bon concen a ions a ising om so wood combus ion by a ac o o 9, om culm combus ion by a ac o o 20, and om bi uminous coal combus ion in domes ic hea ing uni s by a subs an ial ac o o 223. Con e sely, indus ial combus ion o bi uminous coal exhibi ed he lowes le els o ca - bonaceous compounds, accoun ing o a me e 1.6% o PM mass (as shown in Figu e 1). The con- cen a ions o o ganic and elemen al ca bon we e co espondingly low a 72.1 and 20.1 µg m−3 , espec i ely. This diminished p esence o ca bonaceous compounds in he PM emissions om powe plan s likely s ems om he e ec i e ope a ion o exhaus a e ea men sys ems wi hin he lue gas duc s, which e icien ly emo e hese compounds om he pa icula e ma e , lea ing behind mine al and me allic cons i uen s. In he ealm o mobile sou ces, he mass o o al ca bon made up 45% o pa icula e ma e emissions om medium-du y diesel ehicles (MDDV) and a mo e signi ican 70% om ligh -du y diesel ehicles (LDDV). This aligns wi h he indings o He e al.’s s udy in 2017, indica ing ha elemen al ca bon ypically cons i u es up o 56% o he o e all ca bonaceous con en wi hin pa icula e ma e o igina ing om diesel sou ces. Fu he - mo e, acco ding o he men ioned s udy, he emaining po ion, app oxima ely 44%, can be a ibu ed o he low- ola ili y o ganic ac ion (de i ed om uel and lub ica ing oil) and he high- ola ili y o ganic ac ion (associa ed wi h unconsumed uels) [48]. To comp ehensi ely cha ac e ize pa icula e ma e o igina ing om di e se combus ion- ela ed sou ces, he analysis inco po a ed he compu a ion o mass a ios be ween o ganic ca bon and elemen al ca bon (OC/EC). This pa ame e se es as a aluable indica o o he ca bonaceous composi ion wi hin he pa icula e ma e . The highes OC/EC alue o 24.0 was iden i ied in PM de i ed om esiden ial combus ion o bi uminous coal. This heigh ened Ene gies 2023,16, 6514 8 o 16 a io sugges s a p e alence o o ganic ca bon o e elemen al ca bon in his con ex . In he case o domes ic ecopea coal combus ion, an OC/EC alue o 13.2 was eco ded, e lec ing a subs an ial o ganic ca bon p esence ela i e o elemen al ca bon. No ably lowe OC/EC alues we e obse ed o culm combus ion in domes ic hea ing uni s, egis e ing a 4.3. Simila ly, indus ial coal combus ion in powe plan s yielded a ela i ely modes OC/EC alue o 3.6. Fo pa icula e ma e a ising om he combus ion o so wood, an OC/EC alue o 1.2 was no ed. In e es ingly, his alue is no ably lowe —3.5 imes so—compa ed o he alue p oposed by Sillanpää e al., 2006 [ 50 ], which s ood a 4.15. I is pe inen o men ion ha Sillanpää e al., 2006 s udy epo ed a subs an ially low OC/EC a io o 0.8 o diesel ehicles. Con e sely, signi ican ly highe OC/EC a ios we e documen ed o domes ic uel combus ion. The p esence o a subs an ial amoun o o ganic ca bon ela i e o elemen al ca bon could indica e ha he combus ion p ocesses a e no ope a ing op imally, which in u n can lead o he emission o ha m ul and po en ially oxic subs ances. This unde sco es he impo ance o e icien combus ion echniques, p ope uel p epa a ion, and adequa e ai supply o minimize he o ma ion o hese haza dous compounds. The p onounced p e alence o o ganic ca bon o e elemen al ca bon wi hin he pa icula e ma e com- posi ion can likely be a ibu ed o incomple e combus ion p ocesses. This phenomenon gi es ise o he o ma ion o po en ially haza dous compounds, such as polycyclic a o- ma ic hyd oca bons (PAHs). Incomple e combus ion, cha ac e ized by insu icien oxygen a ailabili y, ends o p oduce a highe p opo ion o o ganic ca bonaceous compounds. These compounds a e o med when complex hyd oca bons in he uel a e no comple ely b oken down in o simple componen s like ca bon dioxide. Ins ead, hey unde go pa ial b eakdown, leading o he c ea ion o compounds like PAHs. These compounds a e o conce n due o hei po en ial o pose heal h isks. PAHs a e known o ha e ca cinogenic p ope ies and a e associa ed wi h a ious espi a o y and ca dio ascula ailmen s when inhaled [12,39]. 3.3. PM-Bound Ino ganic Ions The p opo ion o anions wi hin he pa icula e ma e exhibi ed a ia ions con in- gen on he speci ic uel subjec ed o combus ion. The pa icula e ma e s emming om so wood combus ion exhibi ed he lowes anion con en , cons i u ing a me e 1.2% o pa ic- ula e ma e . A sligh ly ele a ed concen a ion o anions, 5.7%, was eco ded o pa icula e ma e esul ing om he combus ion o bi uminous coal in domes ic hea ing uni s (DHUs). This 5.7% equa es o 26,643 µ g m −3 , a concen a ion ou old highe han he summed anion concen a ion om culm combus ion. In he la e case, anions con ibu ed o 17.3% o he pa icula e ma e ’s mass. The composi ion o PM o igina ing om indus ial coal bu ning e ealed anionic con ibu ions o 11% o he PM mass. A no ably dis inc pa e n eme ged in he case o ecopea combus ion wi hin DHUs, whe e anions ook he mos subs an ial sha e, accoun ing o a s iking 67.5% o he mass (Figu e 1). The concen a ion o ino ganic ions wi hin he pa icula e ma e exhibi ed dis inc pa - e ns, wi h he highes concen a ions being obse ed o chlo ide ions (Cl − ) and sulpha e ions (SO 42− ). An o de ly examina ion o hese indings e eals se e al ends (Figu e 2A): • Wi hin pa icula e ma e s emming om so wood combus ion, sulpha e ions ook he lead, con ibu ing a signi ican 60% o he o e all anion mass. Chlo ide ions, hough sligh ly lowe , s ill held subs an ial p ominence, con ibu ing 28% o he anion mass. • The p esence o luo ine ions (F − ) was iden i ied in pa icula e ma e a ising bo h om esiden ial coal combus ion and he indus ial p ocess o coal bu ning. In he o me , he concen a ion o luo ine ions wi h a concen a ion o 500 µ g m −3 accoun ed o 1.5% o he o al anion mass, while in he la e , i ose o 25%. The simila con ibu ion (21% and 24%) o F − mass was also no iced o low-du y and medium-du y diesel ehicles, espec i ely. • In he con ex o esiden ial coal combus ion, chlo ine ions domina ed he anion composi ion, con ibu ing a subs an ial 95% o he anion mass. In coal bu ning in a DHU, sulpha es sha ed a smalle p opo ion, comp ising 2% o he anion mass. Ene gies 2023,16, 6514 9 o 16 • Ecopea coal combus ion and bi uminous coal combus ion in powe plan s displayed he lowes con ibu ions o chlo ide ions. In pa icula e ma e om ecopea coal combus ion, chlo ides con ibu ed a me e 25% o he anion mass. Meanwhile, he anions balance leaned hea ily owa ds sulpha e ions, making up almos 100% o he anion mass. • Chlo ines and sulpha es con ibu ed in 28% and 70%, espec i ely, o anions ac ions o pa icula e ma e om culm combus ion. •Ni a es we e obse ed only in PM de i ed om medium-du y diesel ehicles. Ene gies 2023, 16, 6514 10 o 17 A. WOOD CULM ECO-PEA COAL COAL(In) MDDV LDDV 0 10 20 30 40 50 60 70 80 90 100 The pe cen age sha e o anions in pa icula e ma e mass [%] B. WOOD CULM ECO-PEA COAL COAL(In) MDDV LDDV 0 10 20 30 40 50 60 70 80 90 100 The pe cen age sha e o ca ions in pa icula e ma e mass [%] SO 42- PO 43- NO 3- NO 2- B - Cl - F - Ca 2+ K + Mg 2+ NH 4+ Na + Li + Figu e 2. The sha e o ino ganic ions ((A). anions, (B). ca ions) in pa icula e ma e eal-emi ed om diffe en combus ion- ela ed sou ces. These indings co obo a e exis ing li e a u e, such as he s udy by Popo iche a e al. in 2014 [51], ein o cing he consis ency o he esul s ob ained and enhancing he b oade unde s anding o ca ion dis ibu ion ac oss a ious combus ion sou ces. The ela ionship be ween anions and ca ions, cha ac e ized by he equi alen con- cen a ions a io o anion o ca ion (A/K), exhibi ed dis inc beha iou s ac oss a ious combus ion scena ios. No ably, only in he case o indus ial coal combus ion did he p o- po ions o anions and ca ions achie e equilib ium, indica ed by an A/K alue o 0.95. In he emaining ins ances in ol ing wood, culm, ecopea, coal, medium-du y diesel ehicles (MDDV), and ligh -du y diesel ehicles (LDDV), he A/K a ios displayed speci ic alues o 0.7, 1.6, 1.3, 4.0, 0.16, and 0.06, espec i ely. The mos no ewo hy ele a ion in A/K a io was obse ed o coal bu n in domes ic hea ing uni s, egis e ing a alue o 4.0. This sub- s an ial alue s emmed om an excess o anions, pa icula ly chlo ide ions. I is easona- ble o assume ha hese chlo ides a e p edominan ly bound o NH4+ and Na+. Calcula ing his su plus, he mass concen a ion o chlo ide excess eached 18,567 µg m−3. The in i- guing aspec was he su p isingly low A/K a ios o mobile sou ces, unde sco ing a p o- nounced excess o ca ion concen a ion wi hin pa icula e ma e . This de ia ion om bal- ance could be a ibu ed o he p esence o ca ions in insoluble o ms, which limi s hei abili y o main ain equilib ium wi h anions. he a ying A/K a ios unde line he in ica e chemis y o ion in e ac ions and solubili y pa e ns wi hin emi ed pa icula e ma e . The in ica e in e play be ween anions and ca ions in pa icula e ma e highligh s he com- plex chemis y occu ing du ing combus ion p ocesses. This chemis y is p obably in lu- enced by ac o s such as uel ype, combus ion empe a u e, and eac ion kine ics. 3.4. PM-Bound Me als and Me alloids Among he a ious componen s o pa icula e ma e , me als and me alloids occu- pied he lowes sha e, as depic ed in Figu e 1. The analysis o pa icula e emissions om coal combus ion indica ed ha he cumula i e mass o he analyzed elemen s cons i u ed less han 1% o he o al PM mass, despi e hei collec i e concen a ion being 4400 µg m−3. Figu e 2. The sha e o ino ganic ions (( A ). anions, ( B ). ca ions) in pa icula e ma e eal-emi ed om di e en combus ion- ela ed sou ces. The dis ibu ion o ca ions wi hin he analyzed pa icula e ma e exhibi ed dis inc a ia ions con ingen on he combus ed uel (Figu e 2B). The indings can be sys ema ically elucida ed as ollows: • The cumula i e concen a ion o ca ions in pa icula e ma e om esiden ial coal combus ion amoun ed o 3.600 µ g m −3 , while om ecopea coal bu ning, i s ood a 1.050 µ g m −3 . These igu es con ibu ed o 0.8% and 20.0% o he pa icula e ma e ’s mass, espec i ely. No ably, ca ion mass o igina ing om combus ion exceeded ha om ecopea coal bu ning by a ac o o 2.0, cons i u ing 6% o PM mass. • The lowes concen a ions o ca ions we e egis e ed in pa icles emi ed om so wood combus ion (200 µ g m −3 ) and bi uminous coal combus ion in powe plan s (346 µ g m −3 ). •Ino ganic ions con ibu ed 2% o PM mass o ligh -du y diesel ehicles (LDDV) and 8% o medium-du y diesel ehicles (MDDV). No ably, among he ca ions, sodium ca ions held he highes con ibu ion, comp ising 76% o he ca ion mass o LDDV and 55% o MDDV. Po assium and calcium also held subs an ial p opo ions wi hin his ionic balance. • In PM om coal and ecopea coal combus ion in DHUs, ammonium ions (NH 4+ ) we e p edominan , con ibu ing o o e 80% o he ca ion mass. Lowe NH 4+ con en was obse ed in PM om culm (10%), so wood (38%), and powe plan emissions (20%). • In he case o so wood combus ion, po assium ca ions (K + ) exhibi ed a p e alence simila o ha o ammonium ions. 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