Indoor and outdoor airborne pollutants modify our environment and represent a growing threat to human health worldwide. Airborne pollution effects on respiratory and cardiac health and diseases have been well established, but its impact on skin remains poorly described. Nonetheless, the skin is one of the main targets of pollutants, which reach the superficial and deeper skin layers by transcutaneous and systemic routes. In this review, we report the outcomes of basic and clinical research studies monitoring pollutant levels in human tissues including the skin and hair. We present a current understanding of the biochemical and biophysical effects of pollutants on skin metabolism, inflammatory processes and oxidative stress, with a focus on polyaromatic hydrocarbons and ground‐level ozone that are widespread outdoor pollutants whose effects are mostly studied. We reviewed the literature to report the clinical effects of pollutants on skin health and skin ageing and their impact on some chronic inflammatory skin diseases. We also discuss the potential interactions of airborne pollutants with either ultraviolet radiation or human skin microbiota and their specific impact on skin health.

Titanium dioxide (TiO2) is widely used in a variety of products including cosmetics. TiO2 in its nanoparticle form (nano‐TiO2) is now the only form used as an ultraviolet (UV) filter in sunscreens, but also in some day creams, foundations and lip balms. While its efficacy as a UV filter is proven in the prevention of skin cancers and sunburns, some concerns have been raised about its safety. Indeed, considering its small size, nano‐TiO2 is suspected to penetrate dermal, respiratory or gastrointestinal barriers, disseminate in the body and therefore constitute a potential risk to the consumer. At the skin level, most studies performed in humans or animals showed that nano‐TiO2 did not penetrate beyond the outer layers of stratum corneum to viable cells and did not reach the general circulation, either in healthy or in compromised skin. The Scientific Committee on Consumer Safety (SCCS) considers nano‐TiO2 as a non‐sensitizer and as mild‐ or non‐irritant to skin and concludes in no evidence of carcinogenicity (supported by the European Chemicals Agency), mutagenicity or reproductive toxicity after dermal exposure to nano‐TiO2. According to the SCCS, nano‐TiO2 from sunscreens does not present any health risk when applied on the skin at a concentration up to 25%. However, the SCCS does not recommend the use of nano‐TiO2 in formulations that may lead to exposure of the consumer's lungs by inhalation (sprayable products and powders). Indeed, even if human data are sparse and inconsistent, lung inflammation was reported in animals. In 2016, the EU Cosmetic Regulation made nano‐TiO2 as an authorized UV filter, except in products that could lead to exposure of the lungs. After oral exposure, nano‐TiO2 absorption and toxicity are limited. The incidental oral exposure to nano‐TiO2 contained in lip balms is thus not expected to induce adverse health effects.

Objective To evaluate the capacity of the automatic detection system to accurately grade, from smartphones' selfie pictures, the severity of seven new facial signs added to the nine previously integrated. Methods A two‐step approach was conducted: first, to check on 112 Korean women, how the AI‐based automatic grading system may correlate with dermatological assessments, taken as reference; second, to confirm on 1140 women of three ancestries (African, Asian, and Caucasian) the relevance of the newly input facial signs. Results The sixteen specific Asian facial signs, detected automatically, were found significantly (P < .0001) highly correlated with the clinical evaluations made by two Korean dermatologists (wrinkles: r = .90; sagging: r = .75‐.95; vascular: r = .85; pores: r = .60; pigmentation: r = .50‐.80). When applied at a larger scale on women of different ethnicities, new signs were found of good accuracy and reproducibility, albeit depending on ethnicity. Due to contrast with the innate skin complexion, the facial signs dealing with skin pigmentation were found of a much higher relevance among Asian women than African or Caucasian women. The automatic gradings were even found of a slightly higher accuracy than the clinical gradings. Conclusion The previously used automatic grading system is now completed by adding new facial signs apt at being detected. The continuous development is now integrating some limitations with regard to the constitutive skin complexion of the self‐pictured subjects. Presenting reproducible assessments, highly correlated with medical grading, this system could change tremendously clinical researches, like in epidemiological studies, where it offers an easy, fast, affordable, and confidential approach in the objective quantification of facial signs.

Objective To confirm the robustness and validity of an automatic scoring system, algorithm‐based, that grades the severity of nine facial signs through “selfies” smartphones pictures taken by European Caucasian women through dermatological assessments. Methods 157 Caucasian women from three countries (France, Germany, Spain), of different ages (20–75 years), took one “selfie” image by the frontal camera of their smartphones whereas local dermatologists photographed them with the back camera of the same smartphone. The same nine facial signs of these subjects were initially graded by these local dermatologists, using referential Skin Aging Atlases. All 314 “selfies” images were then further automatically analyzed by the algorithm. The severity of facial signs (wrinkles, pigmentation, ptosis, skin folds etc.) were statistically compared to the assessments made by the three dermatologists, taken as ground truth. Results Highly significant coefficients of correlation (P < 0.001) were found in the three cohorts between the grades provided by the system and those from dermatologists in live. The back camera – of a better resolution than the frontal one – seems affording slightly more significant correlations. However, although significantly correlated, the signs of vascular disorders and cheek skin pores present some disparities that are likely linked to the technical diversity of smartphones or self‐shootings, leading to lower coefficients of correlations. Conclusion This automatic scoring system offers a promising approach in the harmonization of Dermatological assessments of skin facial signs and their changes with age or the follow up of anti‐aging treatments.

Mineral oils and waxes are mixtures of predominantly saturated hydrocarbons consisting of straight‐chain, branched and ring structures with carbon chain lengths greater than C14. They have been used for many decades in skin and lip care cosmetic products due to their excellent skin tolerance as well as their high protecting and cleansing performance and broad viscosity options. In contrast to vegetable oils, mineral oils are non‐allergenic since they are highly stable and not susceptible to oxidation or rancidity. They have a long history of safe use which is confirmed by clinical and epidemiological data. In Europe, mineral oils are only permitted in cosmetics if compliant with purity specifications on polycyclic aromatic hydrocarbons and safety requirements laid down in the European pharmacopoeia and the EU cosmetics regulation EC/1223/2009. The high quality of these mineral oils is assured by robust quality assurance and a refining/purification process designed to exclude substances with carcinogenic potential and to minimize the presence of mineral oil aromatic hydrocarbons. Given their highly lipophilic properties, mineral oils do not penetrate human skin and, thus, are not systemically bioavailable in the body. Moreover, no significant changes in the skin and no effects on any internal organ system have been reported and attributed to the topical application of refined mineral oils. Regarding potential oral exposure from cosmetic lip care products, Cosmetics Europe, the European trade association for the cosmetics and personal care industry, has advised cosmetic manufacturers to only use mineral oil fractions for which recognized food acceptable daily intake (ADI) values apply. The estimated dose of mineral oils ingested via lip care products contributes to <10% of the ADI value and should therefore be considered of no toxicological concern.