Browsing by Subject "Particulate matter"

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  • Sokhi, Ranjeet S.; Singh, Vikas; Querol, Xavier; Finardi, Sandro; Targino, Admir Creso; Andrade, Maria de Fatima; Pavlovic, Radenko; Garland, Rebecca M.; Massague, Jordi; Kong, Shaofei; Baklanov, Alexander; Ren, Lu; Tarasova, Oksana; Carmichael, Greg; Peuch, Vincent-Henri; Anand, Vrinda; Arbilla, Graciela; Badali, Kaitlin; Beig, Gufran; Carlos Belalcazar, Luis; Bolignano, Andrea; Brimblecombe, Peter; Camacho, Patricia; Casallas, Alejandro; Charland, Jean-Pierre; Choi, Jason; Chourdakis, Eleftherios; Coll, Isabelle; Collins, Marty; Cyrys, Josef; da Silva, Cleyton Martins; Di Giosa, Alessandro Domenico; Di Leo, Anna; Ferro, Camilo; Gavidia-Calderon, Mario; Gayen, Amiya; Ginzburg, Alexander; Godefroy, Fabrice; Alexandra Gonzalez, Yuri; Guevara-Luna, Marco; Haque, Sk Mafizul; Havenga, Henno; Herod, Dennis; Horrak, Urmas; Hussein, Tareq; Ibarra, Sergio; Jaimes, Monica; Kaasik, Marko; Kousa, Anu; Kukkonen, Jaakko; Kulmala, Markku; Kuula, Joel; Petäjä, Tuukka (2021)
    This global study, which has been coordinated by the World Meteorological Organization Global Atmospheric Watch (WMO/GAW) programme, aims to understand the behaviour of key air pollutant species during the COVID-19 pandemic period of exceptionally low emissions across the globe. We investigated the effects of the differences in both emissions and regional and local meteorology in 2020 compared with the period 2015-2019. By adopting a globally consistent approach, this comprehensive observational analysis focuses on changes in air quality in and around cities across the globe for the following air pollutants PM2.5, PM10, PMC (coarse fraction of PM), NO2, SO2, NOx, CO, O-3 and the total gaseous oxidant (O-X = NO2 + O-3) during the pre-lockdown, partial lockdown, full lockdown and two relaxation periods spanning from January to September 2020. The analysis is based on in situ ground-based air quality observations at over 540 traffic, background and rural stations, from 63 cities and covering 25 countries over seven geographical regions of the world. Anomalies in the air pollutant concentrations (increases or decreases during 2020 periods compared to equivalent 2015-2019 periods) were calculated and the possible effects of meteorological conditions were analysed by computing anomalies from ERA5 reanalyses and local observations for these periods. We observed a positive correlation between the reductions in NO2 and NOx concentrations and peoples' mobility for most cities. A correlation between PMC and mobility changes was also seen for some Asian and South American cities. A clear signal was not observed for other pollutants, suggesting that sources besides vehicular emissions also substantially contributed to the change in air quality. As a global and regional overview of the changes in ambient concentrations of key air quality species, we observed decreases of up to about 70% in mean NO2 and between 30% and 40% in mean PM2.5 concentrations over 2020 full lockdown compared to the same period in 2015-2019. However, PM2.5 exhibited complex signals, even within the same region, with increases in some Spanish cities, attributed mainly to the long-range transport of African dust and/or biomass burning (corroborated with the analysis of NO2/CO ratio). Some Chinese cities showed similar increases in PM2.5 during the lockdown periods, but in this case, it was likely due to secondary PM formation. Changes in O-3 concentrations were highly heterogeneous, with no overall change or small increases (as in the case of Europe), and positive anomalies of 25% and 30% in East Asia and South America, respectively, with Colombia showing the largest positive anomaly of similar to 70%. The SO2 anomalies were negative for 2020 compared to 2015-2019 (between similar to 25 to 60%) for all regions. For CO, negative anomalies were observed for all regions with the largest decrease for South America of up to similar to 40%. The NO2/CO ratio indicated that specific sites (such as those in Spanish cities) were affected by biomass burning plumes, which outweighed the NO2 decrease due to the general reduction in mobility (ratio of similar to 60%). Analysis of the total oxidant (OX = NO2 + O-3) showed that primary NO2 emissions at urban locations were greater than the O-3 production, whereas at background sites, O-X was mostly driven by the regional contributions rather than local NO2 and O-3 concentrations. The present study clearly highlights the importance of meteorology and episodic contributions (e.g., from dust, domestic, agricultural biomass burning and crop fertilizing) when analysing air quality in and around cities even during large emissions reductions. There is still the need to better understand how the chemical responses of secondary pollutants to emission change under complex meteorological conditions, along with climate change and socio-economic drivers may affect future air quality. The implications for regional and global policies are also significant, as our study clearly indicates that PM2.5 concentrations would not likely meet the World Health Organization guidelines in many parts of the world, despite the drastic reductions in mobility. Consequently, revisions of air quality regulation (e.g., the Gothenburg Protocol) with more ambitious targets that are specific to the different regions of the world may well be required.
  • Belis, C. A.; Karagulian, F.; Amato, F.; Almeida, M.; Artaxo, P.; Beddows, D. C. S.; Bernardoni, V.; Bove, M. C.; Carbone, S.; Cesari, D.; Contini, D.; Cuccia, E.; Diapouli, E.; Eleftheriadis, K.; Favez, O.; El Haddad, I.; Harrison, R. M.; Hellebust, S.; Hovorka, J.; Jang, E.; Jorquera, H.; Kammermeier, T.; Karl, M.; Lucarelli, F.; Mooibroek, D.; Nava, S.; Nojgaard, J. K.; Paatero, P.; Pandolfi, M.; Perrone, M. G.; Petit, J. E.; Pietrodangelo, A.; Pokorna, P.; Prati, P.; Prevot, A. S. H.; Quass, U.; Querol, X.; Saraga, D.; Sciare, J.; Sfetsos, A.; Valli, G.; Vecchi, R.; Vestenius, M.; Yubero, E.; Hopke, P. K. (2015)
    The performance and the uncertainty of receptor models (RMs) were assessed in intercomparison exercises employing real-world and synthetic input datasets. To that end, the results obtained by different practitioners using ten different RMs were compared with a reference. In order to explain the differences in the performances and uncertainties of the different approaches, the apportioned mass, the number of sources, the chemical profiles, the contribution-to-species and the time trends of the sources were all evaluated using the methodology described in Bells et al. (2015). In this study, 87% of the 344 source contribution estimates (SCEs) reported by participants in 47 different source apportionment model results met the 50% standard uncertainty quality objective established for the performance test. In addition, 68% of the SCE uncertainties reported in the results were coherent with the analytical uncertainties in the input data. The most used models, EPA-PMF v.3, PMF2 and EPA-CMB 8.2, presented quite satisfactory performances in the estimation of SCEs while unconstrained models, that do not account for the uncertainty in the input data (e.g. APCS and FA-MLRA), showed below average performance. Sources with well-defined chemical profiles and seasonal time trends, that make appreciable contributions (>10%), were those better quantified by the models while those with contributions to the PM mass close to 1% represented a challenge. The results of the assessment indicate that RMs are capable of estimating the contribution of the major pollution source categories over a given time window with a level of accuracy that is in line with the needs of air quality management. (C) 2015 The Authors. Published by Elsevier Ltd.
  • Booyens, Wanda; Beukes, Johan P.; Van Zyl, Pieter G.; Ruiz-Jimenez, Jose; Kopperi, Matias; Riekkola, Marja-Liisa; Josipovic, Miroslav; Vakkari, Ville; Laakso, Lauri (2019)
    A recent paper reported GCxGC-TOFMS analysis used for the first time in southern Africa to tentatively characterise and semi-quantify 1000 organic compounds in aerosols at Welgegund - a regional background atmospheric monitoring station. Ambient polar organic aerosols characterised are further explored in terms of temporal variations, as well as the influence of meteorology and sources. No distinct seasonal pattern was observed for the total number of polar organic compounds tentatively characterised and their corresponding semi-quantified concentrations (sum of the normalised response factors, Sigma NRFs). However, the total number of polar organic compounds and Sigma NRFs between late spring and early autumn seemed relatively lower compared to the period from mid-autumn to mid-winter, while there was a period during late winter and early spring with significantly lower total number of polar organic compounds and Sigma NRFs. Relatively lower total number of polar organic compounds and corresponding Sigma NRFs were associated with fresher plumes from a source region relatively close to Welgegund. Meteorological parameters indicated that wet removal during late spring to early autumn also contributed to lower total numbers of polar organics and associated Sigma NRFs. Increased anticyclonic recirculation and more pronounced inversion layers contributed to higher total numbers of polar organic species and Sigma NRFs from mid-autumn to mid-winter, while the influence of regional biomass burning during this period was also evident. The period with significantly lower total number of polar organic compounds and Sigma NRFs was attributed to fresh open biomass burning plumes occurring within proximity of Welgegund, consisting mainly of volatile organic compounds and non-polar hydrocarbons. Multiple linear regression substantiated that the temporal variations in polar organic compounds were related to a combination of the factors investigated in this study.
  • Kollanus, Virpi; Tiittanen, Pekka; Niemi, Jarkko V.; Lanki, Timo (2016)
    Introduction: Fine particulate matter (PM2.5) emissions from vegetation fires can be transported over long distances and may cause significant air pollution episodes far from the fires. However, epidemiological evidence on health effects of vegetation-fire originated air pollution is limited, particularly for mortality and cardiovascular outcomes. Objective: We examined association between short-term exposure to long-range transported PM2.5 from vegetation fires and daily mortality due to non-accidental, cardiovascular, and respiratory causes and daily hospital admissions due to cardiovascular and respiratory causes in the Helsinki metropolitan area, Finland. Methods: Days significantly affected by smoke from vegetation fires between 2001 and 2010 were identified using air quality measurements at an urban background and a regional background monitoring station, and modelled data on surface concentrations of vegetation-fire smoke. Associations between daily PM2.5 concentration and health outcomes on i) smoke-affected days and ii) all other days (i.e. non smoke days) were analysed using Poisson time series regression. All statistical models were adjusted for daily temperature and relative humidity, influenza, pollen, and public holidays. Results: On smoke-affected days, 10 mu g/m(3) increase in PM2.5 was associated with a borderline statistically significant increase in cardiovascular mortality among total population at a lag of three days (12.4%, 95% CI -0.2% to 26.5%), and among the elderly (>= 65 years) following same-day exposure (13.8%, 95% CI -0.6% to 30.4%) and at a lag of three days (11.8%, 95% CI -2.2% to 27.7%). Smoke day PM2.5 was not associated with non-accidental mortality or hospital admissions due to cardiovascular causes. However, there was an indication of a positive association with hospital admissions due to respiratory causes among the elderly, and admissions due to chronic obstructive pulmonary disease or asthma among the total population. In contrast, on non-smoke days PM2.5 was generally not associated with the health outcomes, apart from suggestive small positive effects on non-accidental mortality at a lag of one day among the elderly and hospital admissions due to all respiratory causes following same-day exposure among the total population. Conclusions: Our research provides suggestive evidence for an association of exposure to long-range transported PM2.5 from vegetation fires with increased cardiovascular mortality, and to a lesser extent with increased hospital admissions due to respiratory causes. Hence, vegetation-fire originated air pollution may have adverse effects on public health over a distance of hundreds to thousands of kilometres from the fires. (C) 2016 The Authors. Published by Elsevier Inc.
  • Soares, Joana (Finnish Meteorological Institute, 2016)
    Finnish Meteorological Institute Contributions 121
    Atmospheric aerosols are subject to extensive research, due to their effect on air quality, human health and ecosystems, and hold a pivotal role in the Earth’s climate. The first focus of this study is to improve the modelling of aerosol emissions and its dispersion in the atmosphere, in different spatial and temporal scales, and secondly, to integrate the dispersion modelling with population activity data to estimate exposure metrics. The mathematical models used in this study are fully or partially developed by the Finnish Meteorological Institute: a regional-to-global scale chemical transport model SILAM, a local-scale point/line-source dispersion model, UDM/CAR-FMI, and a human exposure and intake fraction assessment model, EXPAND. One of the outcomes of this work was the refinement of the emission modelling for the mesoscale dispersion model. A new parameterisation for bubble-mediated sea salt flux has been developed, taking in to account the effects of wind speed and seawater salinity and temperature. The parameterization is valid for low-to-moderate wind speed, seawater salinity ranging between 0 and 33 ‰, seawater temperature ranging between -2 and 25 °C, and can be applicable to particles with dry diameters raging between 0.01 and 10 μm. The near-real time fire estimation system, IS4FIRES, based on Fire Radiative Power (FRP) measured by the remote sensing instrument MODIS, was refined to reduce the overestimation of particulate matter (PM) emissions by including more vegetation types, improving the diurnal variation, removing misattributed fires from the FRP data, and recalibrating the emission factors. Applying dynamic emission modelling brought more insight to the spatial distribution of these emissions, their contribution to the atmospheric budget, and possible impact on air quality and climate. The modelling shows that sea salt can be transported far over land and contribute up to 6 μg m-3 to PM10 (at annual level). It also indicates that the Mediterranean Sea has sharp gradients of concentration, becoming an interesting area to analyse regarding the feedbacks to the regional climate. According to the predictions, upward scattering by SSA, at TOA, can be up to 0.5 W m-2, and there will be an overall cooling in the future for the North of Europe and warming for the South, due to SSA. The simulations for wildland fires show how the system improves after calibration and the importance vegetation type for the intensity of the emissions. By including misattributed fires, there will be up to 80% overestimation in aerosol optical depth, close to the misattributed sources. The emissions for Helsinki Metropolitan Area (HMA) were revised to bring up-to-date the emissions for traffic and energy sectors, for urban-scale applications. The EXPAND model was revised to combine concentrations and activity data in order to compute parameters such as population exposure or intake fraction. EXPAND includes improvements of the associated urban emission and dispersion modelling system, time use of population, and infiltration coefficients from outdoor to indoor air. This refinement showed that PM2.5 in HMA is mainly originated from long-range transport, with the largest local contributors being vehicular and shipping (at harbours and its vicinity) emissions. At annual level, the population is mostly exposed to PM2.5 indoors (home and work), but the population is acutely exposed while commuting.
  • Mäkelä, Kati; Ollila, Hely; Sutinen, Eva; Vuorinen, Vesa; Peltola, Emilia; Kaarteenaho, Riitta; Myllärniemi, Marjukka (2019)
    Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease with a dismal prognosis and an unknown etiology. Inorganic dust is a known risk factor, and air pollution seems to affect disease progression. We aimed to investigate inorganic particulate matter in IPF lung tissue samples. Using polarizing light microscopy, we examined coal dust pigment and inorganic particulate matter in 73 lung tissue samples from the FinnishIPF registry. We scored the amount of coal dust pigment and particulate matter from 0 to 5. Using energy dispersive spectrometry with a scanning electron microscope, we conducted an elemental analysis of six IPF lung tissue samples. We compared the results to the registry data, and to the population density and air quality data. To compare categorical data, we used Fisher's exact test; we estimated the survival of the patients with Kaplan-Meier curves. We found inorganic particulate matter in all samples in varying amounts. Samples from the southern regions of Finland, where population density and fine particle levels are high, more often had particulate matter scores from 3 to 5 than samples from the northern regions (31/50, 62.0% vs. 7/23, 30.4%, p = 0.02). The highest particulate matter scores of 4 and 5 (n = 15) associated with a known exposure to inorganic dust (p = 0.004). An association between particulate matter in the lung tissue of IPF patients and exposure to air pollution may exist.
  • Hussein, Tareq; Boor, Brandon E.; dos Santos, Vanessa N.; Kangasluoma, Juha; Petäjä, Tuukka; Lihavainen, Heikki (2017)
    Air pollution research and reports have been limited in the Middle East, especially in Jordan with respect to aerosol particle number concentrations. In this study, we utilized a simple "mobile setup" to measure, for the first time, the spatial variation of aerosol concentrations in Eastern Mediterranean. The mobile setup consisted of portable aerosol instruments to measure particle number concentrations (cut off sizes 0.01, 0.02, 0.3, 0.5, 1, 2.5, 5, and 10 mu m), particle mass concentrations (PM1, PM2.5, and PM10), and black carbon concentration all situated on the back seat of a sedan car. The car was driven with open windows to ensure sufficient cabin air ventilation for reliable outdoor aerosol sampling. Although the measurement campaign was two days long, but it provided preliminary information about aerosols concentrations over a large spatial scale that covered more than three quarters of Jordan. We should keep in mind that the presented concentrations reflect on road conditions. The submicron particle concentrations were the highest in the urban locations (e.g., Amman and Zarqa) and inside cities with heavy duty vehicles activities (e.g., Azraq). The highest micron particle concentrations were observed in the southern part of the country and in places close to the desert area (e.g., Wadi Rum and Wadi Araba). The average submicron concentration was 4.9 x 10(3)-120 x 10(3) cm-3 (5.7-86.7 mu g m(-3)) whereas the average micron particle concentration was 1-11 cm(-3) (8-150 mu g m(-3), assume rho(p) = 1 g cm(-3)). The main road passing through Jafr in the eastern part of Jordan exhibited submicron concentration as low as 800 cm(-3). The PM10 concentration consisted of about 40-75% as PM1. The black carbon (BC) concentration variation was in good agreement with the PM1 as well as the submicron particle number concentration.
  • Venter, Andrew D.; van Zyl, Pieter G.; Beukes, Johan P.; Swartz, Jan-Stefan; Josipovic, Miroslav; Vakkari, Ville; Laakso, Lauri; Kulmala, Markku (2018)
    Aerosols consist of organic and inorganic species, and the composition and concentration of these species depends on their sources, chemical transformation and sinks. In this study an assessment of major inorganic ions determined in three aerosol particle size ranges collected for 1year at Welgegund in South Africa was conducted. SO42- and ammonium (NH4+) dominated the PM1 size fraction, while SO42- and nitrate (NO3) dominated the PM1-2.5 and PM2.5-10 size fractions. SO42- had the highest contribution in the two smaller size fractions, while NO3- had the highest contribution in the PM2.5-10 size fraction. SO42- and NO3- levels were attributed to the impacts of aged air masses passing over major anthropogenic source regions. Comparison of inorganic ion concentrations to levels thereof within a source region influencing Welgegund, indicated higher levels of most species within the source region. However, the comparative ratio of SO42- was significantly lower due to SO42- being formed distant from SO2 emissions and submicron SO42- having longer atmospheric residencies. The PM at Welgegund was determined to be acidic, mainly due to high concentrations of SO42-. PM1 and PM1-2.5 fractions revealed a seasonal pattern, with higher inorganic ion concentrations measured from May to September. Higher concentrations were attributed to decreased wet removal, more pronounced inversion layers trapping pollutants, and increases in household combustion and wild fires during winter. Back trajectory analysis also revealed higher concentrations of inorganic ionic species corresponding to air mass movements over anthropogenic source regions.
  • Viippola, Juho Viljami; Whitlow, Thomas; Zhao, Wenlin; Yli-Pelkonen, Vesa Johannes; Mikola, Juha Tapio; Pouyat, Richard; Setälä, Heikki Martti (2018)
    It is often stated that plants remove air pollutants from the urban atmosphere with their large leaf area, thus providing benefits − i.e. ecosystem services − for citizens. However, empirical evidence showing that local-scale air quality is uniformly improved by urban forests is scarce. We studied the influence of conifer-dominated peri-urban forests on the springtime levels of NO2 and particle pollution at different distances from roads, using passive samplers and high time resolution particle counters in a northern climate in Finland. Passive samplers provided average values over a one month period, while active particle counters provided real time measurements of air pollution to mimic human inhalation frequency. NO2 concentrations were slightly higher in forests than in adjacent open areas, while passive particle measurements showed the opposite trend. Active particle monitoring campaigns showed no systematic forest effect for PM2.5, but larger particles were reduced in the forest, corroborating the passive sampling result. Attenuation rates of the mean values of the studied pollutants did not differ between the forest and open habitats. However, high time resolution particle data revealed a distance effect that was apparent only in the forest transect: peak events at the forest edge were higher, while peaks furthest from the road were lower compared to the open transect. Furthermore, the magnitude of PM2.5 peak events was distinctly higher at forest edge than equivalent distance in the open area. Vegetation characteristics, such as canopy cover and tree density, did not explain differences in pollutant levels in majority of cases. Our results imply that evergreen-dominated forests near roads can slightly worsen local air quality regarding NO2 and PM2.5 in northern climates, but that coarser particle pollution can be reduced by such forest vegetation. It seems that the potential of roadside vegetation to mitigate air pollution is largely determined by the vegetation effects on airflow.
  • UF& HLTH Study Grp (2018)
    Background: Although epidemiological studies have reported associations between mortality and both ambient air pollution and air temperature, it remains uncertain whether the mortality effects of air pollution are modified by temperature and vice versa. Moreover, little is known on the interactions between ultrafine particles (diameter Objective: We investigated whether the short-term associations of particle number concentration (PNC in the ultrafine range ( Methods: We first analyzed air temperature-stratified associations between air pollution and total natural (nonaccidental) and cardiovascular mortality as well as air pollution-stratified temperature-mortality associations using city-specific over-dispersed Poisson additive models with a distributed lag nonlinear temperature term in each city. All models were adjusted for long-term and seasonal trend, day of the week, influenza epidemics, and population dynamics due to summer vacation and holidays. City-specific effect estimates were then pooled using random-effects meta-analysis. Results: Pooled associations between air pollutants and total and cardiovascular mortality were overall positive and generally stronger at high relatively compared to low air temperatures. For example, on days with high air temperatures (> 75th percentile), an increase of 10,000 particles/cm(3) in PNC corresponded to a 2.51% (95% CI: 0.39%, 4.67%) increase in cardiovascular mortality, which was significantly higher than that on days with low air temperatures (<25th percentile) [-0.18% (95% CI: -0.97%, 0.62%)]. On days with high air pollution (> 50th percentile), both heat-and cold-related mortality risks increased. Conclusion: Our findings showed that high temperature could modify the effects of air pollution on daily mortality and high air pollution might enhance the air temperature effects.
  • Kervinen, Tommi (Helsingin yliopisto, 2022)
    Ilmansaasteiden ja niistä erityisesti ulkoilman hiukkasten yhteydestä hengitys- sekä sydän- ja verenkiertoelimistön sairauksiin on runsaasti näyttöä. Myös hiukkasten mahdollisesta yhteydestä psykiatriseen sairastavuuteen on julkaistu lukuisia tutkimuksia. Tämä systemaattinen kirjallisuuskatsaus tarkastelee tutkimuksia ulkoilman hiukkasten mahdollisesta yhteydestä ahdistukseen, masennukseen, skitsofreniaan ja itsemurhiin. Kirjallisuushaku suoritettiin Pubmed-tietokannassa 20.5.2020. Yhteensä 166 julkaisusta karsittiin pois katsauksen kriteerien perusteella 150 tutkimusta, ja tarkasteltavaksi valittiin 16 tutkimusta. Kaikissa valituissa tutkimuksissa tarkastelun kohteena on lyhyt- (alle 30 päivää) tai pitkäaikainen (vähintään 30 päivää) altistuminen ainakin ulkoilman pienhiukkasille (PM2.5, halkaisijaltaan alle 2.5 mikrometriä) tai hengitettäville hiukkasille (PM10, halkaisijaltaan alle 10 mikrometriä) sekä altistuksen yhteys ahdistukseen, masennukseen, skitsofreniaan tai itsemurhiin. Päätetapahtumiksi kelpuutin diagnostiset mielenterveyden häiriöt, standardoiduilla kaavakkeilla arvioidut oirekuvat sekä toteutuneet itsemurhat. Neljästä ulkoilman hiukkasten vaikutusta ahdistukseen selvittäneestä tutkimuksesta kolmessa tutkimuksessa hiukkasaltistuksen havaittiin olevan yhteydessä joko ahdistusoireisiin tai ahdistuksen sairaalahoitoihin. Yhdeksästä masennusta käsitelleestä tutkimuksesta kahdeksassa havaittiin hiukkasaltistuksen positiivinen yhteys ja yhdessä peräti käänteinen yhteys joko masennusoireisiin tai -diagnooseihin. Skitsofrenian ja hiukkasaltistuksen yhteyttä selvitti vain yksi tutkimus, jossa havaittiin lyhytaikaisen altistuksen yhteys psykoosioireiden vakavuuteen. Itsemurhien ja hiukkasaltistuksen yhteyttä selvittäneistä neljästä tutkimuksesta kolmessa havaittiin yhteys lyhytaikaiseen altistukseen. Kun tutkimusten tuloksia tarkastelee tarkemmin hiukkaskokojen, altistusaikojen ja päätetapahtumien osalta, on näyttö osittain ristiriitaista tai vähäistä, ja johtopäätösten kanssa on oltava varovainen. Tämän katsauksen tutkimuksista paras näyttö koski lyhytaikaisen PM2,5-altistuksen yhteyttä masennusdiagnooseihin sekä lyhytaikaisen PM10-altistuksen yhteyttä masennusoireisiin ja - diagnooseihin. Iso osa tutkimuksista tehtiin lisäksi korkeiden pitoisuuksien maissa, eikä niitä voi sellaisenaan soveltaa Suomen oloihin.