•OH	hydroxyl radical
4HNE	4-hydroxyl-2-nonenal
6-MWT	6-min walking test
8-OHdG	8-hydroxydeoxyguanosine
A549 cells	adenocarcinomic human alveolar basal epithelial cells
ALI	acute lung injury
AR	allergic rhinitis
ARDS	acute respiratory distress syndrome
BALF	bronchoalveolar lavage fluid
BCSS	breathless-cough-sputum scale
BMSC	bone marrow-derived mesenchymal stem cells
CAT	catalase
CLP	cecal-ligation-and-puncture
COPD	chronic obstructive pulmonary disease
COVID-19	coronavirus disease 2019
CS	cigarette smoke
Drp1	dynamin-related protein 1
EBC	exhaled breath condensate
EGFR	epidermal growth factor receptor
EMT	epithelial-to-mesenchymal transition
ER	endoplasmic reticulum
FAS	fatigue assessment scale
FcεRI	high-affinity IgE receptor
FEV1	forced expiratory volume in 1 s
FGFR4	fibroblast growth factor receptor 4
FVC	forced vital capacity
GPx	glutathione peroxidase
H/R	hypoxia-reoxygenation
H1975	human non-small cell lung cancer cells
H2O2	hydrogen peroxide
HaCaT	aneuploid immortal keratinocyte cell line from adult human skin
HIEC	human intestinal epithelial cells
HIF-1α	hypoxia-inducible factor-1 α
HMGB1	high mobility group box 1 protein
HO-1	hemoxygenase-1
HRS	hydrogen-enriched saline
HRW	hydrogen-enriched water
ICAM-1	intercellular adhesion molecule 1
IgE	immunoglobulin E
IL	interleukin
INF-γ	interferon gamma
ip.	intraperitoneal (injection)
it.	intratracheal (administration)
iv.	intravenous (administration)
LI	lung injury
LPS	lipopolysaccharide
MAPK	mitogen-activated protein kinase
MCP-1	monocyte chemoattractant protein-1
MDA	malondialdehyde
MMP-12	matrix metalloproteinase-12
MP1α	macrophage protein 1α
MPO	myeloperoxidase
MUC5AC	mucin-5AC
NFκB	nuclear factor kappa-light-chain-enhancer of activated B cells
NLRP3	NLR family pyrin domain containing 3
Nrf2	nuclear factor erythroid 2-related factor-2
O2-	superoxide
ONOO⁻	peroxynitrite
OVA	ovalbumin
pCO2	partial pressure of carbon dioxide
PF	pulmonary fibrosis
PGE2	prostaglandin E2
PM2.5	particulate matter of a diameter of less than 2.5 µm
pO2	partial pressure of oxygen
ROS/RNS	reactive oxygen and nitrogen species
SARS-CoV-2	severe acute respiratory syndrome coronavirus-2
SIRT-1	Sirtuin-1
SMA	smooth muscle actin
SMC	structural maintenance of chromosomes complex
SOD	superoxide dismutase
TBARS	thiobarbituric acid reactive substances
TGF1β	transforming growth factor
TIMP-1	tissue inhibitor of metalloproteinase-1
TLR4	toll-like receptor 4
TNF-α	tumor necrosis factor-α
TUNEL	terminal deoxynucleotidyl transferase dUTP nick end labeling
VCAM-1	vascular cell adhesion molecule-1
VE	minute ventilation
VEGF	vascular endothelial growth factor
VEGFR2	vascular endothelial growth factor receptor 2
VILI	ventilatory-induced lung injury
XEN gas	2.4% H2 in air
ZO-1	tight junction protein ZO-1/zonula occludens-1