Smog Episodes in Poland

atmosphere

Article Smog Episodes in Poland

Grzegorz Wielgosi ´nski* and Justyna Czerwi ´nska

Faculty of Process and Environmental Engineering, Lodz University of Technology, Wolczanska 213, 90-924 Lodz, Poland; [email protected] * Correspondence: [email protected]; Tel.: +48-631-37-95

Received: 31 January 2020; Accepted: 10 March 2020; Published: 12 March 2020

Abstract: The phenomenon of above-average air pollution, i.e., smog, in urban areas is known. Two types of smog have been described in the literature: London and Los Angeles smog. They differ in the conditions of formation and areas of occurrence. In recent years, the phenomenon of smog has also been observed in Poland, where the main reason for poor air quality is exceeding the permissible PM10 concentrations. The main source of particulate matter emissions in Poland is the so-called “low emission”, i.e., released by emitters up to 40 m high, mainly from domestic boilers and traffic. Based on the data from the environmental protection inspection, an analysis was carried out of the impact of atmospheric factors, such as atmospheric pressure and air temperature, on air pollution caused by particulate matter in Poland. Next, data concerning the chemical composition of PM10 particulate matter in Poland was analyzed. In the next stage, tests were carried out on ammonia emissions from biomass and coal combustion processes to determine the source of ammonium ions as a component of particulate matter. The results of analyzes and research allowed us to formulate the thesis about the existence of a specific type of smog called “Polish smog” and determine the conditions for its formation.

Keywords: polish smog; PM10 particulate matter; meteorological factors

1. Introduction One of the most important social problems in recent years is the deterioration of air quality. It is widely accepted that the emission of most pollutants is closely related to the volume of industrial production. This means that any increase in production inevitably entails an increase in emissions and vice versa, a reduction in production, e.g., as a result of the economic crisis, which reduces most of the emissions. This thesis is partly true, but the decrease in emissions also results from the improvement of production processes, implementation of new technologies, equipping installations with increasingly better emission-reduction systems or changes in legal regulations. Furthermore, the volume of pollutant emissions usually does not simply translate into an increase in their emissions, i.e., deterioration of air quality. This relationship exists but air pollution is aﬀected by a much larger number of factors, not just the volume of emission. Sources of air pollution are numerous and diverse, both natural and resulting from human activities. The substances most commonly emitted to the atmosphere from commercial activities include sulfur dioxide, nitrogen oxides, particulate matter, volatile organic compounds, heavy metals and odors [1–3]. Large combustion plants, i.e., above all power plants and combined heat and power plants, are considered the most important sources of sulfur dioxide emissions. In second place are housing (local boiler houses) and combustion processes in industry. Nitrogen oxides are emitted mainly from road transport, metallurgy and cement plants. The two air pollution types presented above are the most important reasons for the deterioration of air quality, which is often referred to as smog. Smog is the best known negative eﬀect of air pollution in

Atmosphere 2020, 11, 277; doi:10.3390/atmos11030277 www.mdpi.com/journal/atmosphere Atmosphere 2020, 11, 277 2 of 13 the ground layer of the atmosphere [4–7]. Smog can be called an atmospheric phenomenon consisting of the co-occurrence of air pollution caused by human activity and adverse natural atmospheric phenomena, which results in temperature inversion, and often also fog. Originally the word smog comes from the combination of two words: smoke and fog, and was used to refer to phenomena observed in London in the early 1950s. Today, under the name smog, we usually mean the oversized air pollution in cities arising as a result of emissions from low emitters (residential combustion and cars) under certain meteorological conditions (especially temperature inversion). In the literature, numerous descriptions of two types of smog can be found: acid smog (London type) and photochemical smog (Los Angeles type). Acid smog occurs mainly from November to January. During this time, temperature inversion occurs in the temperate climate zone, i.e., there is an atypical temperature distribution with altitude above the earth surface. During temperature inversion, the temperature increases with height and does not decrease, as it results, among others, from the laws of thermodynamics. The vertical movement of the atmosphere is then strongly inhibited, and in weak wind or windless weather there is a concentration of pollutants near the earth surface [8–10]. Near the ground level an acid aerosol is formed which is toxic to humans and the environment and is also allergic to some parts of the population. As the name suggests, the main components of acid smog acidic compounds formed by absorption of acidic substances resulting from the absorption of acidic gases such as sulfur dioxide, nitrogen oxides, carbon monoxide emitted from combustion processes in drops of water creating fog. The opposite of acid smog is photochemical smog. It arises primarily in the summer months, in subtropical zones, with intense sunlight and air temperature above 30 ◦C[11–14]. The main components of photochemical smog are nitrogen oxides, carbon monoxide and hydrocarbons, and most of all ozone formed as a result of a series of photochemical reactions. Many countries and cities struggle with the problem of smog. In Poland this problem also exists. The highest above-average concentrations are achieved by the following pollutants: particulate matter, benzo(a)pyrene and nitrogen dioxide. While the concentrations of particulate matter and benzo(a)pyrene exceed norms practically throughout the country in large cities and also in smaller towns, the problem of nitrogen dioxide occurs only in the largest cities at busy communication arteries. This is due to the fact that the dominant source of particulate matter and benzo(a)pyrene are domestic furnaces–coal- and wood-fired boilers, and of nitrogen dioxide–cars. In 2018, the World Health Organization published a report on air quality in Europe. In terms of PM2.5, as many as 36 of the 50 most polluted cities in the European Union are in Poland (Figure1). Based on observations made in Poland for several years, it can be concluded that there is another type of smog characteristic of Poland, which can be described as dust smog or “Polish smog”–a term recently coined in the literature [15–17]. Polish smog is characterized by different atmospheric conditions in which it arises. It also has a different composition than London smog where there is a high concentration of sulfur dioxide and carbon monoxide, as well as PM10. The conditions for the formation of Polish smog is discussed in detail later in the article. Atmosphere 2020, 11, 277 3 of 13 Atmosphere 2020, 11, x FOR PEER REVIEW 3 of 14

Figure 1. Fifty most polluted cities in the European Union (average annual concentrations of PM2.5) Figure 1. Fifty most polluted cities in the European Union (average annual concentrations of PM2.5) [18]. [18]. In 2018, Rawicki et al. [19] showed that due to meteorological conditions and the occurrence of smogIn episodes, 2018, Rawicki Poland et could al. [19] be dividedshowed intothat threedue to areas: meteorological I—southern, conditions in which and smog the episodes occurrence last theof longestsmog episodes, and occur Poland most often, could II—central be divided with into moderate three areas: frequency I—southern, of smog in episodeswhich smog and episodes III—northern, last the longest and occur most often, II—central with moderate frequency of smog episodes and where smog episodes occur sporadically. This is due to the fact that a constant balance dominates III—northern, where smog episodes occur sporadically. This is due to the fact that a constant in the southern part of Poland, and a much larger share of unstable balance occurs in the northern balance dominates in the southern part of Poland, and a much larger share of unstable balance part [20,21]. The division of Poland according to the frequency of smog episodes is shown in Figure2. occurs in the northern part [20,21]. The division of Poland according to the frequency of smog episodes is shown in Figure 2.

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Figure 2. “Smoggy”“Smoggy” regions regions with with the highest PM co concentrationncentration in air in Poland [19]. [19].

2. Experimental Experimental The highhigh andand very very high high concentrations concentrations of dustof dust pollution pollution observed observed in Poland in Poland in the in winter the winter season seasonfor several for several years, bothyears, PM10 both PM10 and PM2.5, and PM2.5, are commonly are commonly called called smog. smog. However, However, it seems it seems that that this thisphenomenon phenomenon differs differs from from the smog the episodessmog episodes described described in the literaturein the literature in the winter in the (the winter so-called (the so-calledLondon-type London-type smog) and smog) in the summerand in the (the summer so-called (the Los so-called Angeles-type Los smog).Angeles-type To verify smog). this hypothesis, To verify thisit was hypothesis, decided to analyzeit was thedecided conditions to analyze for the formationthe conditions of oversized for the concentrations formation of of certainoversized air concentrationspollutants in Poland of usingcertain data air from pollutants State Inspection in Poland for Environmental using data Protectionfrom State monitoring Inspection stations. for EnvironmentalIt was also decided Protection to answer monitoring the question stations. why It during was also smog decided episodes to inanswer Poland the we question do not report why duringexceeding smog the permissibleepisodes in concentrationsPoland we do of not sulfur repo dioxidert exceeding (as it happened the permissible in 1952 in concentrations London), despite of sulfurthe fact dioxide that the (as source it happened of air pollution in 1952 inin winter London), is solid despite fuel the combustion fact that processes,the source in of Poland, air pollution which in is winterprimarily is coal,solid woodfuel combustion and partly illegal processes, incineration in Poland, of municipal which is waste primarily in household coal, wood stoves. and The partly main illegalsource incineration of poor air qualityof municipal in Poland waste is veryin household high concentrations stoves. The ofmain dust, source as well of aspoor benzo(a)pyrene, air quality in whilePoland no is exceedances very high concentrations of permitted sulfur of dust, dioxide as well concentrations as benzo(a)pyrene, has been while observed. no exceedances Therefore, theof permittednext hypothesis sulfur was dioxide adopted concentrations that ammonia has emission been observed. from solid fuelTherefore, combustion the next processes hypothesis may be was the adoptedcause of sulfurthat ammonia dioxide bindingemission in from the formsolid offuel ammonium combustion sulfate. processes The resultsmay be of the our cause investigations of sulfur dioxideon combustion binding processes in the form showed of ammonium that such ammoniasulfate. The emissions results of occur our duringinvestigations the combustion on combustion of coal, processesbiomass and showed sewage that sludge such asammonia well. Therefore, emissions available occur during literature the datacombustion on the chemical of coal, biomass composition and sewageof PM10 sludge and PM2.5 as well. dust Therefore, present in available high concentrations literature data in atmospheric on the chemical air in somecomposition Polish citiesof PM10 was andanalyzed. PM2.5 The dust results present of the in analysis high concentrations confirmed the adoptedin atmospheric research air hypotheses, in some whichPolish is cities presented was analyzed.in the later The part ofresults this publication.of the analysis confirmed the adopted research hypotheses, which is presentedThe first in the step later in determining part of this publication. how the Polish smog differed from others known from the literature was theThe analysis first step of meteorologicalin determining conditions how the conducivePolish smog to itsdiffered formation. from To others check known how exactly from theythe literatureinfluence thiswas process, the analysis an analysis of meteorological was carried out conditions of four major conducive Polish cities:to its Gdańsk,Łformation.ó d´z,ZabrzeTo check how and exactlyKraków. they Gdańsklocated influence this in process, Northern an Poland analysis lies was onthe carried Baltic out Sea, of Ł fouród´zis major in the Polish center cities: of the Gda country,ńsk, Łandódź Zabrze, Zabrze and and Krak Kraków.ów, one Gda ofń thesk mostlocated polluted in Northern cities inPoland Poland, lies are on in the its Baltic southern Sea, part.Łódź Based is in the on centerthe data of of the the country, Chief Inspectorate and Zabrze for and Environmental Kraków, one Protection of the most in Poland,polluted the cities emission in Poland, information are in onits southernPM10 was part. collected Based and on comparedthe data of with the Chief the prevailing Inspectorate atmospheric for Environmental conditions Protection (air temperature in Poland, and theatmospheric emission pressure).information The on recorded PM10 was hourly collected concentrations and compared and meteorological with the prevailing parameters atmospheric such as conditionspressure and (air temperature temperature come and from atmospheric stationary pres stationssure). for The continuous recorded air hourly quality concentrations monitoring located and meteorologicalin the analyzed cities.parameters such as pressure and temperature come from stationary stations for continuous air quality monitoring located in the analyzed cities.

Atmosphere 2020, 11, 277 5 of 13 Atmosphere 2020, 11, x FOR PEER REVIEW 5 of 14 Atmosphere 2020, 11, x FOR PEER REVIEW 5 of 14 3. Results 3. Results 3. Results The analysis covered data from the winter seasons in the years 2014 to 2017. PM10 mass The analysis covered data from the winter seasons in the years 2014 to 2017. PM10 mass concentrationThe analysis data covered (one-hour data values) from and the meteorological winter seasons data in included the years the 2014 months to 2017. January, PM10 February, mass concentration data (one-hour values) and meteorological data included the months January, Marchconcentration and December. data (one-hour The same values) relationships and meteor were observedological indata all analyzedincluded cases,the months which is January, why the February, March and December. The same relationships were observed in all analyzed cases, which resultsFebruary, for March 2017 are and discussed December. in this The publication. same relationships were observed in all analyzed cases, which is why the results for 2017 are discussed in this publication. is whyThe the first results atmospheric for 2017 factorare discussed that was in taken this publication. into account was the air temperature. Results of the The first atmospheric factor that was taken into account was the air temperature. Results of the analyzesThe forfirst all atmospheric cities are presented factor that in was Figures taken3–6 into. account was the air temperature. Results of the analyzes for all cities are presented in Figures 3–6. analyzesThese for figures all cities show are thepresented effect of in temperature Figures 3–6. on PM10 concentration. In all cases, it was found These figures show the effect of temperature on PM10 concentration. In all cases, it was found that theThese PM10 figures concentration show the effect decreased of temperature as the temperature on PM10 increased. concentration. The highestIn all cases, concentrations it was found of that the PM10 concentration decreased as the temperature increased. The highest concentrations of PM10that the were PM10 observed concentration in the temperature decreased as range the temp of 10erature to 0 C. increased. The highest concentrations of PM10 were observed in the temperature range of –10 to 0 ◦°C. PM10 were observed in the temperature range of −–10 to 0 °C.

Figure 3. The effect of temperature on PM10 concentration in Łódź in 2017. Figure 3. The effect eﬀect of temperature on PM10 concentration in Łóódd´zinź in 2017.

Figure 4. The effect of temperature on PM10 concentration in Kraków in 2017. Figure 4. The effect effect of temperature on PM10 concentration in KrakKrakówów in 2017.2017. Figures 3 to 6 show the effect of temperature on PM10 concentration. In all cases, it was found Figures3 3– 6to show 6 show the the e ff ecteffect of temperatureof temperature on PM10on PM10 concentration. concentration. In all In cases, all cases, it was it was found found that that the PM10 concentration decreased as the temperature increased. The highest concentrations of thethat PM10 the PM10 concentration concentration decreased decreased as the as temperature the temperature increased. increased. The highest The highest concentrations concentrations of PM10 of PM10 were observed in the temperature range of –5 to 0 °C. werePM10 observed were observed in the temperaturein the temperature range ofrange5 to of 0 –5C. to 0 °C. − ◦ Another atmospheric factor for which the analysis was carried out was atmospheric pressure. Figures7–10 show the relationship between atmospheric pressure and PM10 concentration. Based on the figures, it was found that the relationship was inverse than in the case of temperature. The higher the atmospheric pressure, the greater the PM10 concentration.

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Figure 5. TheThe effect eﬀect of temperature on PM10 concentration in Zabrze in 2017. Figure 5. The effect of temperature on PM10 concentration in Zabrze in 2017.

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The second factor differentiating both atmospheric phenomena is the lack of elevated sulfur dioxide concentrations in smog episodes in Poland despite the actual identical source of pollutant emissions—combustion of solid fossil fuels in domestic furnaces. To explain this phenomenon, it was decided to analyze the chemical composition of particulate matter forming Polish smog. For this purpose, the works of Mathews et al. [22] and Degórka et al. [23] were used. In 2009, Mathews et al. [22] conducted a study on determining the concentration of ions in the air and their percentage in the mass of fine particulate matter, i.e., the PM2.5 fraction and coarse particulate matter—PM2.5-10. The research was carried out in the summer and winter seasons in the urban background area in Zabrze, in southern Poland. The results of the analyzes are presented below. Figure 6. TheThe effect effect of temperature on PM10 concentration in GdańskinGdańsk in 2017. Figure 6. The effect of temperature on PM10 concentration in Gdańsk in 2017. Another atmospheric factor for which the analysis was carried out was atmospheric pressure. FiguresAnother 7 atmospheric to 10 show thefactor relationship for which betweenthe analys atmosphericis was carried pressure out was and atmospheric PM10 concentration. pressure. BasedFigures on the 7figures, to 10 show it was the found relationship that the relationbetweenship atmospheric was inverse pressure than in and the PM10case of concentration. temperature. TheBased higher on the the figures, atmospheric it was pressure,found that the the greater relation theship PM10 was concentration. inverse than in the case of temperature. The higherAt all analyzed the atmospheric measuring pressure, stations, the itgreater was observed the PM10 that concentration. the concentration of PM10 decreased with Atincreasing all analyzed air temperature measuring stations,and increased it was with observed increasing that the atmospheric concentration pressure. of PM10 These decreased results ledwith to increasing the thesis air that temperature Polish smog and differed increased from with other increasing ones described atmospheric in thepressure. literature, These i.e., results acid Londonled to the smog thesis and that photochemical Polish smog smog. differed The fromspecific other feature ones of described Polish smog in theis the literature, presence i.e., of highacid concentrationsLondon smog andof PM10 photochemical at high pressure smog. Theand specific negative feature temperatures. of Polish Thissmog happens is the presence when, inof highhigh pressureconcentrations weather, of anticyclonePM10 at high circulation pressure of and masses negative of dry, temperatures. frosty air from This the happens east flow when, into Poland.in high Atpressure night, weather, there are anticyclone strong temperature circulation ofdrops, masses while of dry, during frosty the air fromday solarthe east radiation flow into causes Poland. a temperatureAt night, there increase. are strong The near-ground temperature layer drops, of the while atmosphere during getsthe daywarmer solar while radiation on the causes ground a surface,temperature especially increase. in snowy The near-ground winters, it is layer very ofcold. the These atmosphere are excellent gets warmer conditions while for on the the formation ground ofsurface, temperature especially inversion in snowy and winters, thus for it theis very accumulati cold. Theseon of are pollutants excellent inconditions the inversion for the layer formation at the Figure 7. The effect of atmospheric pressure on PM10 concentration in Łódź in 2017. earthof temperature surface.Figure The inversion source 7. The e ffofandect these ofthus atmospheric pollutants for the accumulati pressure is the so-called onon PM10 of concentration“lowpollutants emission”, in in the Łó i.e., d´zininversion the 2017. emission layer atfrom the domesticearth surface. heating The systemssource of fired these with pollutants low-quality is the so-calledcoal and “low wood. emission”, Low temperatures i.e., the emission obviously from increasedomesticAt all heat heating analyzed demand, systems measuring which fired further stations, with increases itlow-quality was observed the stream coal that andof the emitted wood. concentration pollutants. Low temperatures of PM10 decreased obviously with increasingincreaseThe heatdifference air demand, temperature between which and furtherPolish increased increases smog with and increasingthe streamLondon atmosphericof smogemitted is pollutants. pressure.primarily Thesein meteorological results led to theconditions. thesisThe thatdifference While Polish London smogbetween dismogffered Polish is fromformed smog other in onesandlow- weather describedLondon conditionssmog in the literature,is primarilyand at i.e.,temperatures acidin meteorological London slightly smog andaboveconditions. photochemical zero, PolishWhile smogLondon smog. is Theformedsmog specific is during formed feature frosty in oflow- high Polishweather weather. smog conditions is the presence and at of temperatures high concentrations slightly above zero, Polish smog is formed during frosty high weather.

Figure 8. The effect of atmospheric pressure on PM10 concentration in Kraków in 2017.

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Atmosphere 2020, 11, 277 7 of 13 of PM10 at high pressure and negative temperatures. This happens when, in high pressure weather, anticyclone circulation of masses of dry, frosty air from the east ﬂow into Poland. At night, there are strong temperature drops, while during the day solar radiation causes a temperature increase. The near-ground layer of the atmosphere gets warmer while on the ground surface, especially in snowy winters, it is very cold. These are excellent conditions for the formation of temperature inversion and thus for the accumulation of pollutants in the inversion layer at the earth surface. The source of these pollutants is the so-called “low emission”, i.e., the emission from domestic heating systems ﬁred with low-quality coal and wood. Low temperatures obviously increase heat demand, which further increases the stream of emitted pollutants. Figure 7. The effect of atmospheric pressure on PM10 concentration in Łódź in 2017.

Figure 8. The effect eﬀect of atmospheric pressure on PM10 concentration inin KrakKrakówów inin 2017.2017.

Figure 9. The eﬀect of atmospheric pressure on PM10 concentration in Zabrze in 2017.

The diﬀerence between Polish smog and London smog is primarily in meteorological conditions. While London smog is formed in low-weather conditions and at temperatures slightly above zero, Polish smog is formed during frosty high weather. The second factor diﬀerentiating both atmospheric phenomena is the lack of elevated sulfur dioxide concentrations in smog episodes in Poland despite the actual identical source of pollutant emissions—combustion of solid fossil fuels in domestic furnaces. To explain this phenomenon, it was decided to analyze the chemical composition of particulate matter forming Polish smog. For this purpose, the works of Mathews et al. [22] and Degórka et al. [23] were used.

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Figure 10. The eﬀect of atmospheric pressure on PM10 concentration in Gda´nskin 2017.

In 2009, Mathews et al. [22] conducted a study on determining the concentration of ions in the air and their percentage in the mass of fine particulate matter, i.e., the PM2.5 fraction and coarse particulate matter—PM2.5-10. The research was carried out in the summer and winter seasons in the urban background area in Zabrze, in southern Poland. The results of the analyzes are presented below. Figure 11 shows the share of cation and anion concentrations in the total ions associated with fine particulate matter. In all analyzed cases, the main components of fine particulate matter were sulfate and ammonium ions. In the winter season, in fine particulate matter, sulfate ions account for about 40% of the composition, and in the winter season this value increases to about 69%–76%. This is due to the seasonality of heating and the increase in sulfur dioxide emissions from local boiler houses. Ammonium ions in the winter and summer seasons do not show large fluctuations and remain at the levelAtmosphere from 2020 12%, 11 to, x 15%.FOR PEER REVIEW 9 of 14

Figure 11. Percentage of cations and anions in the total content of ions associated with ﬁne particles on Figure 11. Percentage of cations and anions in the total content of ions associated with fine particles winter and summer working days and weekends in Zabrze in 2009 [22]. on winter and summer working days and weekends in Zabrze in 2009 [22]. Figure 12 shows the share of cation and anion concentrations in the total concentration of ions associatedFigure with 12 shows coarse the particulate share of cation matter. and In thisanion case, concentrations it can be seen in that, the total unlike concentration the ﬁne particulate of ions matter,associated the with concentration coarse particulate of sulfate matter. ion throughout In this case, the it year can remainedbe seen that, at a unlike level of the around fine particulate 55%. The matter, the concentration of sulfate ion throughout the year remained at a level of around 55%. The share of ammonium ions in coarse particulate matter was much smaller than in fine particulate matter amounting to about 4%. Three years later Degórka et al. conducted tests on the composition of PM2.5 at three different monitoring stations in Poland. Two of them were in the northern part of Poland, in the cities of Gdańsk and Diabla Góra, while the third one was in the south of the country in Katowice. Results of the test are presented below.

Figure 12. Mass percentage of cations and anions in the total content of ions associated with coarse particles on winter and summer working days and weekends in Zabrze in 2009 [22].

Figures 13 and 14 present the results of analyzes for Northern Poland. For both sulfate and ammonium ion concentrations, a similar trend could be observed depending on the season of the

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Figure 11. Percentage of cations and anions in the total content of ions associated with fine particles on winter and summer working days and weekends in Zabrze in 2009 [22].

AtmosphereFigure2020 12, 11 shows, 277 the share of cation and anion concentrations in the total concentration of9 ions of 13 associated with coarse particulate matter. In this case, it can be seen that, unlike the fine particulate matter, the concentration of sulfate ion throughout the year remained at a level of around 55%. The share ofof ammoniumammonium ions ions in in coarse coarse particulate particulate matter matter was was much much smaller smaller than inthan fine in particulate fine particulate matter amountingmatter amounting to about to 4%. about 4%. Three years later DegDegórkaórka et al. conducted tests on the composition of PM2.5 at three didifferentfferent monitoring stationsstations in in Poland. Poland. Two Two of themof them were were in the in northernthe northern part ofpart Poland, of Poland, in the citiesin the of cities Gdańsk of andGdań Diablask and G Diablaóra, while Góra, the while third the one third was inone the was south in the of the south country of the in country Katowice. in Katowice. Results of theResults test areof the presented test are below.presented below.

Figure 12. Mass percentage of cations and anions in the total content of ions associated with coarse particles on winter and summer working days andand weekendsweekends inin ZabrzeZabrze inin 20092009 [[22].22].

Figures 13 and 14 presentpresent thethe resultsresults ofof analyzesanalyzes forfor NorthernNorthern Poland.Poland. For both sulfate and Atmosphere 2020, 11, x FOR PEER REVIEW 10 of 14 ammonium ionion concentrations,concentrations, a a similar similar trend trend could coul bed be observed observed depending depending on theon seasonthe season of the of year. the year.It could It could also be also seen be that seen there that was there a smaller was a percentagesmaller percentage of these ions of these than inions the than case in of Zabrze,the case i.e., of

Zabrze,a town locatedi.e., a town in the located southern in the part southern of the country part of (Figuresthe country 11 and (Figures 12). 11 and 12).

Figure 13. MassMass percentage percentage of of PM2.5 components in in pa particularrticular seasons of 2010 in the monitoring station in Diabla Góra Góra [[23].23].

Figure 14. Mass percentage of PM2.5 components in particular seasons of 2010 in the monitoring station in Gdańsk [23].

Figure 15 presents the results of analyzes for Katowice—the city in the southern part of the country. In autumn and winter a higher percentage of sulfate ions were recorded than in the case of Gdańsk and Diabla Góra. Based on Figures 13 to 15, it can be seen that the concentration of sulfate ions in PM2.5 was the highest in summer. On the basis of this thesis, it can be concluded that it is not related to heating seasonality occurring in the country. As mentioned earlier, London smog contains mainly particles of sulfur dioxide and carbon monoxide, while Polish smog can be described as dust smog. The significant presence of sulfate and ammonium ions in Polish smog, which most likely form ammonium sulfate, raises the question of the source of ammonia for binding sulfur dioxide produced in combustion processes.

Atmosphere 2020, 11, x FOR PEER REVIEW 10 of 14 year. It could also be seen that there was a smaller percentage of these ions than in the case of Zabrze, i.e., a town located in the southern part of the country (Figures 11 and 12).

AtmosphereFigure2020 13., 11 Mass, 277 percentage of PM2.5 components in particular seasons of 2010 in the monitoring10 of 13 station in Diabla Góra [23].

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In 2016, Wielgosiński [24] published results of the research on ammonia emissions from sewage sludge incineration processes. They showed that sewage sludge from the Combined Sewage Treatment Plant in Łódź contains significant amounts of ammonia which is released in the combustion process. To confirm that ammonia is emitted from combustion processes, ammonia emissions were measured during biomass and coal combustion [25] in the temperature range from 400 to 900 °C. The processFigure 14.14. of Masssample percentage combustion of PM2.5 was components carried out in in particularpa articular high-temperature seasons of 2010 electric in the monitoringfurnacemonitoring with a horizontalstation working in Gda´nsk[Gdańsk chamber [23].23]. in the presence of air. The furnace exhaust gases were directed to a scrubber system filled with 0.1 M sulfuric acid. The amount of ammonia absorbed in this way was Figure 15 presents the results of analyzes for Katowice—the city in the southern part of the analyzedFigure using 15 presents the Nessler the results method of analyzes[26–28]. forStudies Katowice—the have shown city that in the as southernthe temperature part of the increases, country. country. In autumn and winter a higher percentage of sulfate ions were recorded than in the case of theIn autumn amount and of winterammonia a higher emitted percentage decrease ofs sulfate to reach ions the were highest recorded value than at in 400 the case°C. In of Gda´nskandthe case of Gdańsk and Diabla Góra. Based on Figures 13 to 15, it can be seen that the concentration of sulfate biomass,Diabla G ónamelyra. Based rye on straw Figures at 40013–15 °C,, it ammonia can be seen emissions that the concentrationwere at the level of sulfate of 12 ionsmg/g in (Figure PM2.5 was16). ions in PM2.5 was the highest in summer. On the basis of this thesis, it can be concluded that it is Forthe highestthe combustion in summer. of Oncoal the with basis the of thistrade thesis, name it can Ekogroszek be concluded Saturn, that itthe is nothighest related emission to heating of not related to heating seasonality occurring in the country. ammoniaseasonality at occurringthe level of in 1 the mg/g country. was reported at 500 °C (Figure 17). As mentioned earlier, London smog contains mainly particles of sulfur dioxide and carbon monoxide, while Polish smog can be described as dust smog. The significant presence of sulfate and ammonium ions in Polish smog, which most likely form ammonium sulfate, raises the question of the source of ammonia for binding sulfur dioxide produced in combustion processes.

Figure 15. MassMass percentage percentage of of PM2.5 components in in pa particularrticular seasons of 2010 in the monitoring station in Katowice [23]. [23].

As mentioned earlier, London smog contains mainly particles of sulfur dioxide and carbon monoxide, while Polish smog can be described as dust smog. The signiﬁcant presence of sulfate and ammonium ions in Polish smog, which most likely form ammonium sulfate, raises the question of the source of ammonia for binding sulfur dioxide produced in combustion processes.

Figure 16. Ammonia emission from the combustion of rye straw.

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In 2016, Wielgosiński[24] published results of the research on ammonia emissions from sewage sludge incineration processes. They showed that sewage sludge from the Combined Sewage Treatment Plant in Łód´zcontains significant amounts of ammonia which is released in the combustion process. To confirm that ammonia is emitted from combustion processes, ammonia emissions were measured during biomass and coal combustion [25] in the temperature range from 400 to 900 ◦C. The process of sample combustion was carried out in a high-temperature electric furnace with a horizontal working chamber in the presence of air. The furnace exhaust gases were directed to a scrubber system filled with 0.1 M sulfuric acid. The amount of ammonia absorbed in this way was analyzed using the Nessler method [26–28]. Studies have shown that as the temperature increases, the amount of ammonia emitted decreases to reach the highest value at 400 ◦C. In the case of biomass, namely rye straw at 400 ◦C, ammonia emissions were at the level of 12 mg/g (Figure 16). For the combustion of coal withFigure the 15. trade Mass name percentage Ekogroszek of PM2.5 Saturn, components the highest in particular emission seasons of ammonia of 2010 in at the monitoring level of 1 mg /g was reportedstation in atKatowice 500 ◦C [23]. (Figure 17).

Atmosphere 2020, 11, x FORFigure PEER REVIEW 16. AmmoniaAmmonia emission from the combustion of rye straw. 12 of 14

Figure 17. Ammonia emissions from the coal combustion process.

The observed emission of ammonia from combustion processes may explain the presence of ammonium ions in particulate matter composition in Polish cities. It can be assumed that the emitted ammonia reacts with sulfur dioxide, which results in a significant reduction of its emission and the formation of ammonium sulfate as the main component of the particulate matter.

4. Conclusions This publication presents the results of considerations on the phenomenon of Polish smog and the conditions of its formation. First, results of the analysis of the impact of atmospheric conditions (atmospheric pressure and temperature) on the volume of PM10 emission were presented. The analysis was carried out on four cities located in Poland: Łódź, Kraków, Zabrze and Gdańsk. Based on the results, it was found that in all cities the concentration of PM10 particulate matter decreased with increasing temperature. The highest concentrations of PM10 were observed in the temperature range of –5 to 0 °C. In the case of atmospheric pressure, an inverse relationship was observed. The higher the atmospheric pressure, the greater the concentration of PM10 particulate matter observed. The most important element in determining the differences between Polish and London smog was the determination of the impact of weather conditions on the process of Polish smog formation. Then a review of the literature on the chemical composition of PM10 particulate matter was prepared. The analysis showed a significant presence of sulfate and ammonium ions in Polish smog. The results of research on ammonia emissions from the biomass (rye straw) and coal combustion process (Ekogroszek Ekosun) confirmed the appearance of ammonium ions. Based on the aforementioned results, it can be concluded that the ammonia emitted into the atmosphere most likely reacts with sulfur dioxide, which significantly reduces its emission. As a result of this reaction, the main component of the particulate matter in Polish “dusty” smog is ammonium sulfate, not gaseous sulfur dioxide as in the case of London smog. Thus, in our opinion, based on the analysis presented in this paper, it can be concluded that episodes of high concentrations of PM10 and PM2.5 dust occurring in Poland in the winter season can be considered as a kind of smog, other than described so far in the literature.

Author Contributions: Conceptualization, supervision - Grzegorz Wielgosiński; investigation, writing - Justyna Czerwińska.; All authors have read and agreed to the published version of the manuscript.

Funding: This research received no external funding.

Conflicts of Interest: The authors declare no conflicts of interest.

Atmosphere 2020, 11, 277 12 of 13

The observed emission of ammonia from combustion processes may explain the presence of ammonium ions in particulate matter composition in Polish cities. It can be assumed that the emitted ammonia reacts with sulfur dioxide, which results in a signiﬁcant reduction of its emission and the formation of ammonium sulfate as the main component of the particulate matter.

4. Conclusions This publication presents the results of considerations on the phenomenon of Polish smog and the conditions of its formation. First, results of the analysis of the impact of atmospheric conditions (atmospheric pressure and temperature) on the volume of PM10 emission were presented. The analysis was carried out on four cities located in Poland: Łód´z, Kraków, Zabrze and Gda´nsk. Based on the results, it was found that in all cities the concentration of PM10 particulate matter decreased with increasing temperature. The highest concentrations of PM10 were observed in the temperature range of 5 to 0 C. − ◦ In the case of atmospheric pressure, an inverse relationship was observed. The higher the atmospheric pressure, the greater the concentration of PM10 particulate matter observed. The most important element in determining the differences between Polish and London smog was the determination of the impact of weather conditions on the process of Polish smog formation. Then a review of the literature on the chemical composition of PM10 particulate matter was prepared. The analysis showed a significant presence of sulfate and ammonium ions in Polish smog. The results of research on ammonia emissions from the biomass (rye straw) and coal combustion process (Ekogroszek Ekosun) confirmed the appearance of ammonium ions. Based on the aforementioned results, it can be concluded that the ammonia emitted into the atmosphere most likely reacts with sulfur dioxide, which significantly reduces its emission. As a result of this reaction, the main component of the particulate matter in Polish “dusty” smog is ammonium sulfate, not gaseous sulfur dioxide as in the case of London smog. Thus, in our opinion, based on the analysis presented in this paper, it can be concluded that episodes of high concentrations of PM10 and PM2.5 dust occurring in Poland in the winter season can be considered as a kind of smog, other than described so far in the literature.

Author Contributions: Conceptualization, supervision—G.W.; investigation, writing—J.C.; All authors have read and agreed to the published version of the manuscript. Funding: This research received no external funding. Conﬂicts of Interest: The authors declare no conﬂicts of interest.

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