Table 2.

Conditions from smoke from cigarettes/diesel exhaust/gas stove exhaust

Authors, year (reference)	Pollutant exposure	Type of Study	Respiratory condition of focus	Co-existing conditions	Number of subjects	Types of analysed serum markers and results
Kostikas et al., 2013 [41]	Second hand smoke exposure	Randomised controlled crossover trial	Range of inhibited lung capacities	N/A	9 females (9 males)	Cotinine: increase in level observed immediately post-O3 exposure and remained increased until the end of the trial.
						Lung function changes in FEV1 (significant reduction (F = 38.416, P < 0.001)) and FEF25-75 (significant reduction (F = 10.633, P < 0.001))
						FEV1/FVC ratio: significant reduction (P < 0.001)
						No significant changes observed in FVC (F = 0.270, P = 0.946) or PEF (F = 1.274, P = 0.300)
Calciano et al., 2018 [42]	Oxidative stress (cause from smoking or natural environment)	Population-based, multicentre, (multi)case-control study	Asthma	Smokers	140 female cases of asthma (total 287 cases)	Eosinophil, basophil, and lymphocyte levels: positively associated with increased risk of higher severity of respiratory symptom when paired with shortness of breath at rest as a sign.
Yamamoto et al., 2013 [43]	DE	Double-blinded, randomised crossover study	Asthma	N/A	13 participants (sex ratio unspecified but no significance between sexes)	Four microRNA candidates – hsa-miR-144, hsa-miR-30e, hsa-miR-21, hsa-miR-215.
						hsa-miR-144: increased levels post-DE exposure.
						hsa-miR-21: marginally significant results which were not discussed.
						Other microRNAs were not significant.
Olopade et al., 2017 [44]	Oxidative stress (stove kerosene vs ethanol vs firewood), ambient air: 72-h mean PM2.5	Randomised controlled trial	Lung function (cough, phlegm, wheeze, chest tightness, etc.)	Pregnant, but none with possibility of high-risk pregnancy	324 females	TNF-α: improved levels in households that used firewood prior to trial enrollment and shifted to ethanol, thus, cleaner fuels reduced inflammation.
						IL-8: increased at a lower rate among the ethanol vs kerosene stove users and the ethanol group when compared with kerosene users at baseline and the control group.

CRP – C-reactive protein, DE – diesel exhaust, FEF25–75 – forced expiratory flow at 25% to 75% of the pulmonary volume, FEV1 – forced expiratory volume in 1 second, FVC – forced vital capacity, hsa-miR – human microRNA, IL-8 – Interleukin 8, MOSES – Multicenter Ozone Study in oldEr Subjects, O₃ – ozone, PEF – peak expiratory flow, PM2.5 – particulate matter with a diameter of less than 2.5 micrometers, ROS – reactive oxygen species, TNF-α – tumor necrosis factor-alpha