Journal of Environment Pollution and Human Health
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Journal of Environment Pollution and Human Health. 2019, 7(1), 15-26
DOI: 10.12691/jephh-7-1-3
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Comparison of Indoor Air Quality in Schools: Urban vs. Industrial 'Oil & Gas' Zones in Akwa Ibom State – Nigeria

Aniefiok E. Ite1, 2, , Thomas A. Harry3, Clement O. Obadimu1 and Ifiok O. Ekwere1

1Department of Chemistry, Akwa Ibom State University, P. M. B. 1017, Uyo, Akwa Ibom State, Nigeria

2Research and Development Unit, Akwa Ibom State University, P. M. B. 1017, Uyo, Akwa Ibom State, Nigeria

3Department of Geology, Akwa Ibom State University, P. M. B. 1017, Uyo, Akwa Ibom State, Nigeria

Pub. Date: May 19, 2019

Cite this paper:
Aniefiok E. Ite, Thomas A. Harry, Clement O. Obadimu and Ifiok O. Ekwere. Comparison of Indoor Air Quality in Schools: Urban vs. Industrial 'Oil & Gas' Zones in Akwa Ibom State – Nigeria. Journal of Environment Pollution and Human Health. 2019; 7(1):15-26. doi: 10.12691/jephh-7-1-3


This study was carried out to assess indoor air quality (IAQ) in schools in Akwa Ibom State of Nigeria during the rainy (June – July) and dry (November – December) seasons of 2018. IAQ parameters were examined to assess pollutant levels in schools within Akwa Ibom State in single setting only (naturally ventilated classrooms). Schools were randomly selected from two zones: zone 1 which is located within the Capital City (Uyo metropolis) and represents the 'urban sector', and zone 2 which is located within the southern part of the state in close proximity to the oil and gas industrial region and represents the 'industrial sector'. Indoor air investigation included the following parameters: particulate matter (PM1, PM2, PM5, and PM10), carbon monoxide (CO), carbon dioxide (CO2) levels, temperature and relative humidity, which were simultaneously measured in fourteen (14) sampling days using Fluke 985 Particle Counter and Fluke 975 AirMeter. Multiple statistically analysis techniques were used to compare IAQ parameters and test for significant differences between the zones (urban vs. industrial) and annual seasonal variations. The concentrations of particulate matter (PM) in the naturally ventilated classroom in industrial zone during the rainy season ranged from 5152 – 5984 μg/m3 for PM1; 2744 – 3207 μg/m3 for PM2; 137 – 149 μg/m3 for PM5; 38 – 46 μg/m3 for PM10 and in urban zone, the concentrations of PM ranged from 1978 – 2491 μg/m3 for PM1; 1010 – 1311 μg/m3 for PM2; 38 – 56 μg/m3 for PM5; 15 – 24 μg/m3 for PM10. During the dry season, the concentrations of PM in the naturally ventilated classroom in industrial zone ranged from 6138 – 6999 μg/m3 for PM1; 2984 – 3980 μg/m3 for PM2; 146 – 159 μg/m3 for PM5; 47 – 59 μg/m3 for PM10 and in urban zone, the concentrations of PM ranged from 2556 – 3972 μg/m3 for PM1; 1911 – 2311 μg/m3 for PM2; 51 – 66 μg/m3 for PM5; 18 – 34 μg/m3 for PM10. Results of this study has revealed that the concentrations of PM1, PM2, PM5, and PM10 measured in the naturally ventilated classroom in industrial zone were significantly (p < 0.001) higher than those measured in the urban zone during both rainy and dry seasons. In this present study, the concentrations of PM10 measured were found to be much lower than the ambient maximum contaminant level for airborne PM10 standard promulgated by the United States Environmental Protection Agency (US–EPA) (150 μg/m3 daily average and 50 μg/m3 annual average) and World Health Organization (WHO) PM10 guidelines values (50 μg/m3 daily average and 20 μg/m3 annual average). Apart from re–suspension of atmospheric particles, anthropogenic activities in industrial zone significantly influenced the measured concentrations of PM compared to those measured in urban zone. In addition, the lower concentration of CO and CO2 measured indicated adequate air exchange at the time of the assessment in the naturally ventilated classrooms during the sampling period. The results obtained reveal important contributions towards understanding of airborne PM distribution patterns and the available data can be used for making public health policies.

indoor air quality particulate matter schools; exposure Akwa Ibom State Nigeria

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[1]  Ite, A. E., and U. J. Ibok, “Gas Flaring and Venting Associated with Petroleum Exploration and Production in the Nigeria's Niger Delta,” American Journal of Environmental Protection, 1 (4). 70-77, 2013.
[2]  Ite, A. E., U. J. Ibok, M. U. Ite, and S. W. Petters, “Petroleum Exploration and Production: Past and Present Environmental Issues in the Nigeria's Niger Delta,” American Journal of Environmental Protection, 1 (4). 78-90, 2013.
[3]  Ite, A. E., U. F. Ufot, M. U. Ite, I. O. Isaac, and U. J. Ibok, “Petroleum Industry in Nigeria: Environmental Issues, National Environmental Legislation and Implementation of International Environmental Law,” American Journal of Environmental Protection, 4 (1). 21-37, 2016.
[4]  Kampa, M., and E. Castanas, “Human health effects of air pollution,” Environmental Pollution, 151 (2). 362-367, 2008.
[5]  Kelly, F. J., G. W. Fuller, H. A. Walton, and J. C. Fussell, “Monitoring air pollution: use of early warning systems for public health,” Respirology, 17 (1). 7-19, 2012.
[6]  Lippmann, M., “Particulate matter (PM) air pollution and health: regulatory and policy implications,” Air Quality, Atmosphere & Health, 5 (2). 237-241, 2011.
[7]  Ite, A. E., C. O. Ogunkunle, C. O. Obadimu, E. R. Asuaiko, and U. J. Ibok, “Particulate Matter and Staff Exposure in an Air-Conditioned Office in Akwa Ibom State University - Nigeria,” Journal of Atmospheric Pollution, 5 (1). 24-32, 2017.
[8]  Cohen, A. J., H. R. Anderson, B. Ostro, K. D. Pandey, M. Krzyzanowski, N. Künzli, K. Gutschmidt, C. Pope III, I. Romieu, and J. M. Samet, “Urban Air Pollution,” Comparative Quantification of Health Risks: Global and Regional Burden of Disease Attributable to Selected Major Risk Factors, M. Ezzati, A. Lopez, A. Rodgers and C. J. L. Murray, eds., pp. 1353-1433, Geneva: World Health Organization, 2004.
[9]  Wiseman, C. L. S., and F. Zereini, “Part I - Airborne Particulate Matter: Sources, Composition and Concentration,” Urban Airborne Particulate Matter: Origin, Chemistry, Fate and Health Impacts, F. Zereini and C. L. S. Wiseman, eds., pp. 1-2, Berlin, Heidelberg: Springer Berlin Heidelberg, 2011.
[10]  Pöschl, U., “Atmospheric Aerosols: Composition, Transformation, Climate and Health Effects,” Angewandte Chemie International Edition, 44 (46). 7520-7540, 2005.
[11]  Godwin, C., and S. Batterman, “Indoor air quality in Michigan schools,” Indoor Air, 17 (2). 109-121, 2007.
[12]  Madureira, J., I. Paciência, C. Pereira, J. P. Teixeira, and E. d. O. Fernandes, “Indoor air quality in Portuguese schools: levels and sources of pollutants,” 26 (4). 526-537, 2016.
[13]  Lee, S. C., and M. Chang, “Indoor and outdoor air quality investigation at schools in Hong Kong,” Chemosphere, 41 (1). 109-113, 2000.
[14]  Fromme, H., D. Twardella, S. Dietrich, D. Heitmann, R. Schierl, B. Liebl, and H. Rüden, “Particulate matter in the indoor air of classrooms—exploratory results from Munich and surrounding area,” Atmospheric Environment, 41 (4). 854-866, 2007.
[15]  Vilčeková, S., P. Kapalo, Ľ. Mečiarová, E. K. Burdová, and V. Imreczeová, “Investigation of Indoor Environment Quality in Classroom - Case Study,” Procedia Engineering, 190 496-503, 2017.
[16]  Yousaf, A. R., and N. Khan, “The study of particulate matter concentration in schools of Lahore,” Nature Environment and Pollution Technology, 12 (2). 289-296, 2013.
[17]  Moschandreas, D. J., and K. L. Vuilleumier, “ETS levels in hospitality environments satisfying ASHRAE standard 62-1989: “ventilation for acceptable indoor air quality”,” Atmospheric Environment, 33 (26). 4327-4340, 1999.
[18]  Santamouris, M., A. Synnefa, M. Asssimakopoulos, I. Livada, K. Pavlou, M. Papaglastra, N. Gaitani, D. Kolokotsa, and V. Assimakopoulos, “Experimental investigation of the air flow and indoor carbon dioxide concentration in classrooms with intermittent natural ventilation,” Energy and Buildings, 40 (10). 1833-1843, 2008.
[19]  Synnefa, A., E. Polichronaki, E. Papagiannopoulou, M. Santamouris, G. Mihalakakou, P. Doukas, P. A. Siskos, E. Bakeas, A. Dremetsika, A. Geranios, and A. Delakou, “An Experimental Investigation of the Indoor Air Quality in Fifteen School Buildings in Athens, Greece,” International Journal of Ventilation, 2 (3). 185-201, 2003.
[20]  Jovanović, M., B. Vučićević, V. Turanjanin, M. Živković, and V. Spasojević, “Investigation of indoor and outdoor air quality of the classrooms at a school in Serbia,” Energy, 77 42-48, 2014.
[21]  Almeida, S. M., N. Canha, A. Silva, M. d. C. Freitas, P. Pegas, C. Alves, M. Evtyugina, and C. A. Pio, “Children exposure to atmospheric particles in indoor of Lisbon primary schools,” Atmospheric Environment, 45 (40). 7594-7599, 2011.
[22]  Yang, W., J. Sohn, J. Kim, B. Son, and J. Park, “Indoor air quality investigation according to age of the school buildings in Korea,” Journal of Environmental Management, 90 (1). 348-354, 2009.
[23]  Verriele, M., C. Schoemaecker, B. Hanoune, N. Leclerc, S. Germain, V. Gaudion, and N. Locoge, “The MERMAID study: indoor and outdoor average pollutant concentrations in 10 low-energy school buildings in France,” 26 (5). 702-713, 2016.
[24]  Cartieaux, E., M. A. Rzepka, and D. Cuny, “Qualité de l’air à l’intérieur des écoles,” Archives de Pediatrie, 18 (7). 789-796, 2011.
[25]  Nkwocha, E. E., R. O. J. I. J. o. E. S. Egejuru, and Technology, “Effects of industrial air pollution on the respiratory health of children,” 5 (4). 509-516, 2008.
[26]  Abdel-Salam, M. M. M., “Investigation of indoor air quality at urban schools in Qatar,” Indoor and Built Environment, 28 (2). 278-288, 2017.
[27]  de Gennaro, G., P. R. Dambruoso, A. D. Loiotile, A. Di Gilio, P. Giungato, M. Tutino, A. Marzocca, A. Mazzone, J. Palmisani, and F. J. E. C. L. Porcelli, “Indoor air quality in schools,” 12 (4). 467-482, 2014.
[28]  de Gennaro, G., P. R. Dambruoso, A. D. Loiotile, A. Di Gilio, P. Giungato, M. Tutino, A. Marzocca, A. Mazzone, J. Palmisani, and F. Porcelli, “Indoor air quality in schools,” Environmental Chemistry Letters, 12 (4). 467-482, 2014.
[29]  Meininghaus, R., A. Kouniali, C. Mandin, and A. Cicolella, “Risk assessment of sensory irritants in indoor air—a case study in a French school,” Environment International, 28 (7). 553-557, 2003.
[30]  Kim, K.-H., E. Kabir, and S. Kabir, “A review on the human health impact of airborne particulate matter,” Environment International, 74 136-143, 2015.
[31]  Celo, V., and E. Dabek-Zlotorzynska, “Concentration and Source Origin of Trace Metals in PM2.5 Collected at Selected Canadian Sites within the Canadian National Air Pollution Surveillance Program,” Urban Airborne Particulate Matter: Origin, Chemistry, Fate and Health Impacts, F. Zereini and C. L. S. Wiseman, eds., pp. 19-38, Berlin, Heidelberg: Springer Berlin Heidelberg, 2011.
[32]  Iavicoli, I., V. Leso, L. Fontana, and A. Bergamaschi, “Occupational Exposure to Urban Airborne Particulate Matter: A Review on Environmental Monitoring and Health Effects,” Urban Airborne Particulate Matter: Origin, Chemistry, Fate and Health Impacts, F. Zereini and C. L. S. Wiseman, eds., pp. 501-525, Berlin, Heidelberg: Springer Berlin Heidelberg, 2011.
[33]  Jahn, H. J., A. Schneider, S. Breitner, R. Eißner, M. Wendisch, and A. Krämer, “Particulate matter pollution in the megacities of the Pearl River Delta, China – A systematic literature review and health risk assessment,” International Journal of Hygiene and Environmental Health, 214 (4). 281-295, 2011.
[34]  Calkovska, A., and E. Herting, “Exogenous surfactant in respiratory distress syndrome,” Applied Technologies in Pulmonary Medicine, A. M. Esuinas, ed., pp. 205-209, Basel: Karger Publishers, 2010.
[35]  Frew, A. J., S. R. Doffman, K. Hurt, and R. Buxton-homas, “Respiratory Disease,” Kumar & Clark Clinical Medicine, P. J. Kumar and M. L. Clark, eds., pp. 791-866, Saunders: Elsevier 2005.
[36]  Guaita, R., M. Pichiule, T. Mate, C. Linares, and J. Diaz, “Short-term impact of particulate matter (PM(2.5)) on respiratory mortality in Madrid,” International Journal of Environmental Health Research, 21 (4). 260-274, 2011.
[37]  Janssen, N. A. H., P. Fischer, M. Marra, C. Ameling, and F. R. Cassee, “Short-term effects of PM2.5, PM10 and PM2.5–10 on daily mortality in the Netherlands,” Science of the Total Environment, 463–464 20-26, 2013.
[38]  Halonen, J. I., T. Lanki, T. Yli-Tuomi, P. Tiittanen, M. Kulmala, and J. Pekkanen, “Particulate air pollution and acute cardiorespiratory hospital admissions and mortality among the elderly,” Epidemiology, 20 (1). 143-153, 2009.
[39]  Du, Y., X. Xu, M. Chu, Y. Guo, and J. Wang, “Air particulate matter and cardiovascular disease: the epidemiological, biomedical and clinical evidence,” Journal of Thoracic Disease, 8 (1). E8-E19, 2016.
[40]  Brook, R. D., S. Rajagopalan, C. A. Pope, J. R. Brook, A. Bhatnagar, A. V. Diez-Roux, F. Holguin, Y. Hong, R. V. Luepker, and M. A. Mittleman, “Particulate matter air pollution and cardiovascular disease,” Circulation, 121 (21). 2331-2378, 2010.
[41]  Pope, C. A., and D. W. Dockery, “Health Effects of Fine Particulate Air Pollution: Lines that Connect,” Journal of the Air & Waste Management Association, 56 (6). 709-742, 2006.
[42]  Davidson, C. I., R. F. Phalen, and P. A. Solomon, “Airborne Particulate Matter and Human Health: A Review,” Aerosol Science and Technology, 39 (8). 737-749, 2005.
[43]  Linares, C., and J. Diaz, “Short-term effect of concentrations of fine particulate matter on hospital admissions due to cardiovascular and respiratory causes among the over-75 age group in Madrid, Spain,” Public Health, 124 (1). 28-36, 2010.
[44]  Strak, M., G. Hoek, M. Steenhof, E. Kilinc, K. J. Godri, I. Gosens, I. S. Mudway, R. van Oerle, H. M. H. Spronk, F. R. Cassee, F. J. Kelly, R. M. Harrison, B. Brunekreef, E. Lebret, and N. A. H. Janssen, “Components of ambient air pollution affect thrombin generation in healthy humans: the RAPTES project,” Occupational and Environmental Medicine, 70 (5). 332-340, 2013.
[45]  Brunekreef, B., and S. T. Holgate, “Air pollution and health,” Lancet, 360 (9341). 1233-1242, 2002.
[46]  Heudorf, U., V. Neitzert, and J. Spark, “Particulate matter and carbon dioxide in classrooms – The impact of cleaning and ventilation,” International Journal of Hygiene and Environmental Health, 212 (1). 45-55, 2009.
[47]  Graudenz, G. S., C. H. Oliveira, A. Tribess, C. Mendes, M. R. D. O. Latorre, and J. Kalil, “Association of air-conditioning with respiratory symptoms in office workers in tropical climate,” Indoor Air, 15 (1). 62-66, 2005.
[48]  Al-Hemoud, A., L. Al-Awadi, M. Al-Rashidi, K. A. Rahman, A. Al-Khayat, and W. Behbehani, “Comparison of indoor air quality in schools: Urban vs. Industrial 'oil & gas' zones in Kuwait,” Building and Environment, 122 50-60, 2017.
[49]  Cavaleiro Rufo, J., J. Madureira, I. Paciencia, K. Slezakova, C. Pereira Mdo, L. Aguiar, J. P. Teixeira, A. Moreira, and E. Oliveira Fernandes, “Children exposure to indoor ultrafine particles in urban and rural school environments,” Environ Sci Pollut Res Int, 23 (14). 13877-13885, 2016.
[50]  Jo, W.-K., and J.-Y. Lee, “Indoor and outdoor levels of respirable particulates (PM10) and Carbon Monoxide (CO) in high-rise apartment buildings,” Atmospheric Environment, 40 (32). 6067-6076, 2006.
[51]  WHO, Air Quality Guidelines: Global Update 2005: Particulate Matter, Ozone, Nitrogen dioxide, and Sulfur dioxide, Copenhagen, Denmark: World Health Organization, 2006.
[52]  Goyal, R., and M. Khare, “Indoor–outdoor concentrations of RSPM in classroom of a naturally ventilated school building near an urban traffic roadway,” Atmospheric Environment, 43 (38). 6026-6038, 2009.
[53]  Tippayawong, N., P. Khuntong, C. Nitatwichit, Y. Khunatorn, and C. Tantakitti, “Indoor/outdoor relationships of size-resolved particle concentrations in naturally ventilated school environments,” Building and Environment, 44 (1). 188-197, 2009.
[54]  Chithra, V. S., and S. M. Shiva Nagendra, “Indoor air quality investigations in a naturally ventilated school building located close to an urban roadway in Chennai, India,” Building and Environment, 54 159-167, 2012.
[55]  Thatcher, T. L., and D. W. Layton, “Deposition, resuspension, and penetration of particles within a residence,” Atmospheric Environment, 29 (13). 1487-1497, 1995.
[56]  Kalimeri, K. K., D. E. Saraga, V. D. Lazaridis, N. A. Legkas, D. A. Missia, E. I. Tolis, and J. G. Bartzis, “Indoor air quality investigation of the school environment and estimated health risks: Two-season measurements in primary schools in Kozani, Greece,” Atmospheric Pollution Research, 7 (6). 1128-1142, 2016.
[57]  Mendell, M. J., and G. A. Heath, “Do indoor pollutants and thermal conditions in schools influence student performance? A critical review of the literature,” Indoor Air, 15 (1). 27-52, 2005.
[58]  Shendell, D. G., R. Prill, W. J. Fisk, M. G. Apte, D. Blake, and D. Faulkner, “Associations between classroom CO2 concentrations and student attendance in Washington and Idaho,” Indoor Air, 14 (5). 333-341, 2004.
[59]  Seppänen, O. A., W. J. Fisk, and M. J. Mendell, “Association of Ventilation Rates and CO2 Concentrations with Health andOther Responses in Commercial and Institutional Buildings,” Indoor Air, 9 (4). 226-252, 1999.
[60]  Daisey, J. M., W. J. Angell, and M. G. Apte, “Indoor air quality, ventilation and health symptoms in schools: an analysis of existing information,” Indoor Air, 13 (1). 53-64, 2003.
[61]  Ramachandran, G., J. L. Adgate, S. Banerjee, T. R. Church, D. Jones, A. Fredrickson, and K. Sexton, “Indoor air quality in two urban elementary schools--measurements of airborne fungi, carpet allergens, CO2, temperature, and relative humidity,” Journal of Occupational and Environmental Hygiene, 2 (11). 553-566, 2005.
[62]  Polednik, B., “Particulate matter and student exposure in school classrooms in Lublin, Poland,” Environmental Research, 120 134-139, 2013.
[63]  Parker, J. L., R. R. Larson, E. Eskelson, E. M. Wood, and J. M. Veranth, “Particle size distribution and composition in a mechanically ventilated school building during air pollution episodes,” Indoor Air, 18 (5). 386-393, 2008.
[64]  Gusten, J., and O. Strindehag, “Experiences of measures taken to improve the air quality in schools,” Air Infiltration Review, 16 (3). 5-8, 1995.
[65]  Offor, I. F., G. U. Adie, and G. R. E. E. Ana, “Review of Particulate Matter and Elemental Composition of Aerosols at Selected Locations in Nigeria from 1985 – 2015,” Journal of Health and Pollution, 6 (10). 1-18, 2016.
[66]  Efe, S. I., “Spatial distribution of particulate air pollution in Nigerian cities: Implications for human health,” Journal of Environmental Health Research, 7 (2). 107-116, 2008.
[67]  US-EPA, A Brief Guide to Mold, Moisture, and Your Home, U.S. Environmental Protection Agency: CreateSpace Independent Publishing Platform, 2017.
[68]  WHO, WHO Guidelines for Indoor Air Quality: Selected Pollutants, World Health Organization: WHO, 2010.
[69]  Penney, D. G., Carbon Monoxide Poisoning: Taylor & Francis, 2008.
[70]  Mullin, R. C., Electrical Wiring Residential: Based on the 2005 National Electric Code: Thomson Delmar Learning, 2004.
[71]  Wu, Y.-C., and S. A. Batterman, “Proximity of schools in Detroit, Michigan to automobile and truck traffic,” Journal of Exposure Science and Environmental Epidemiology, 16 457, 2006.
[72]  Ashrae, Standard 55-2013 User's Manual: ANSI/ASHRAE Standard 55-2013, Thermal Environmental Conditions for Human Occupancy: ASHRAE Research, 2016.
[73]  Beamish, L. A., E. Wine, and A. R. Osornio-Vargas, “Air pollution: An environmental factor contributing to intestinal disease,” Journal of Crohn's and Colitis, 5 (4). 279-286, 2011.
[74]  Salim, S. Y., G. G. Kaplan, and K. L. Madsen, “Air pollution effects on the gut microbiota: a link between exposure and inflammatory disease,” Gut microbes, 5 (2). 215-219, 2014.
[75]  Kish, L., N. Hotte, G. G. Kaplan, R. Vincent, R. Tso, M. Ganzle, K. P. Rioux, A. Thiesen, H. W. Barkema, E. Wine, and K. L. Madsen, “Environmental particulate matter induces murine intestinal inflammatory responses and alters the gut microbiome,” PLoS One, 8 (4). e62220, 2013.
[76]  Salim, S. Y., J. Jovel, E. Wine, G. G. Kaplan, R. Vincent, A. Thiesen, H. W. Barkema, and K. L. Madsen, “Exposure to ingested airborne pollutant particulate matter increases mucosal exposure to bacteria and induces early onset of inflammation in neonatal IL-10-deficient mice,” Inflammatory Bowel Diseases, 20 (7). 1129-1138, 2014.
[77]  Grigg, J., “Particulate matter exposure in children: relevance to chronic obstructive pulmonary disease,” Proceedings of the American Thoracic Society, 6 (7). 564-569, 2009.
[78]  Peters, A., D. W. Dockery, J. E. Muller, and M. A. Mittleman, “Increased particulate air pollution and the triggering of myocardial infarction,” Circulation, 103 (23). 2810-2815, 2001.
[79]  Kaplan, G. G., J. Hubbard, J. Korzenik, B. E. Sands, R. Panaccione, S. Ghosh, A. J. Wheeler, and P. J. Villeneuve, “The inflammatory bowel diseases and ambient air pollution: a novel association,” The American journal of gastroenterology, 105 (11). 2412-2419, 2010.
[80]  Hart, J. E., F. Laden, R. C. Puett, K. H. Costenbader, and E. W. Karlson, “Exposure to traffic pollution and increased risk of rheumatoid arthritis,” Environmental Health Perspectives, 117 (7). 1065-1069, 2009.
[81]  Tornqvist, H., N. L. Mills, M. Gonzalez, M. R. Miller, S. D. Robinson, I. L. Megson, W. Macnee, K. Donaldson, S. Soderberg, D. E. Newby, T. Sandstrom, and A. Blomberg, “Persistent endothelial dysfunction in humans after diesel exhaust inhalation,” American Journal of Respiratory and Critical Care Medicine, 176 (4). 395-400, 2007.
[82]  Losacco, C., A. J. E. S. Perillo, and P. Research, “Particulate matter air pollution and respiratory impact on humans and animals,” 25 (34). 33901-33910, 2018.