Table 1.

Effects of Particulate matter (PM) in the skin.

Skin effects	Pollutants	Type of study	Skin damage	Mechanism skin damage	References
Oxidative stress/inflammation	PM10	In vitro	↑ROS	↑NOX ↑COX-2/PGE2	(Lee et al., 2016a)
		In vitro	Inhibited proliferation	↑AhR-MAPK signalling ↑CYP1A1 ↑MMP1 ↑Genes of cell aging.	(Qiao et al., 2017)
	PM2.5	In vitro	↑ROS ↑IL-1β ↑IL-6	↑Cryopyrin/NALP3 ↑NF-κB	(Zhang et al., 2017b)
		In vitro	↑ROS	↑TLR5 ↑NOX4	(Ryu et al., 2019)
	PM 5.85µm	In vitro	↑ROS ↑IL-8, ↑IL-1β	↑TPRV ↑NF-κB	(Kwon et al., 2018)
	PM10	In vivo BALB/c nude mice	Inflammation in skin	↑AhR ↑NOX ↑COX-2/PG-2	(Lee et al., 2016a)
Skin barrier dysfunction	PM10	In vitro	↓Filaggrin	↑AhR ↑COX2/PGE2.	(Lee et al., 2016b)
	PM2.5	In vitro	↓KRT 10 ↓Desmocollin ↓Claudin 1	↑CYP1A1 CYP1B1 ↑COX2 ↑NF-κB	(Pan et al., 2015)
		In vitro	↓KRT 16	↑Caspase 3 ↑Bax	(Nguyen et al., 2019)
			↓Keratinocyte proliferation ↑Keratinocyte apoptosis	↑p53
		In vivo BALB/c mice	Dermal inflammatory cells infiltration		(Jin et al., 2018)
Extracellular matrix dysfunction	PM10	In vitro	↑MMP-1 ↑MMP-3 ↓ Collagen	↑CYP1A1, CYP1B1 ↓TGF-β	(Park et al., 2018)

AhR, aryl hydrocarbon receptor; CYP1A1, CYP1B1, cytochrome P450 (CYP1A1, CYP1B1); COX, cyclooxygenase; IL, interleukin; KRT, keratin; MAPK, mitogen-activated protein kinases; MMP, matrix metalloproteinase; NF-kB, nuclear factor kappa B; Nrf2, nuclear factor erythroid 2-like 2; NOX, NADH-oxidase; PGE, prostaglandin E; ROS, reactive oxygen species; TGF-β, transforming growth factor β; TLR, toll-like receptors; TNF-α, tumor necrosis factor α.