Exposome extrinsic factors in the tropics: The need for skin protection beyond solar UV radiation

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Exposome extrinsic factors in the tropics: The need for skin protection beyond solar UV radiation

Marcelo de Paula Corrêa

^a,

⁎ , Alexandre Germano Marciano

^a

, Vanessa Silveira Barreto Carvalho

^a

, Plínio Marcos Bernardo de Souza

^a

, Júlia da Silveira Carvalho Ripper

^b

, Daniel Roy

^c

,

Lionel Breton

^d

, Rodrigo De Vecchi

^b

aInstituto de Recursos Naturais, Universidade Federal de Itajubá, Itajubá, MG, Brazil

bL'Oréal Brasil Pesquisa e Inovação, Rio de Janeiro, RJ, Brazil

cL'Oréal Research & Innovation, Clark, NJ, USA

dL'Oréal Research & Innovation, Aulnay-sous-Bois, France

H I G H L I G H T S

• Harmful environmental conditions are common in the daily lives in subtropics.

• High UV doses, thermal discomfort, and PAH exposure were routinely observed.

• Deleterious conditions occur even on cloudy days and wintertime.

• Anthracene amounts founded can exacerbate skin damages under sunny conditions.

• Skin damage is not only related to the sun, but a wide set of environmental factors.

G R A P H I C A L A B S T R A C T

a b s t r a c t a r t i c l e i n f o

Article history:

Received 17 January 2021

Received in revised form 30 March 2021 Accepted 30 March 2021

Available online 5 April 2021 Editor: Anastasia Paschalidou

Keywords:

Exposome Ultraviolet radiation Air pollution Thermal comfort Photoprotection Skin health

Environmental factors such as solar ultraviolet radiation (UV), air pollution, and variations in the air temperature (T) and relative humidity (RH) affect skin health. However, it is still unclear what effects on the skin may occur as the result of these combined exposures. This study was designed to quantify environmental exposures during routine daily activities to provide quantitative metrics that inspire future studies on exposome and human health. Two bicyclists were equipped with instruments to collect specific data concerning UV (at different angles), T, RH, ground- level ozone (O3), and chemical exposures. Measurements were conducted in the summer and winter seasons of 2016–2017 in four touristic and urban Brazilian cities. Erythemal UV doses (EryD) exceeding the minimal erythemal doses (MED) for phototype V (EryD > 600 Jm⁻²) were registered in most tours, including cloudy weather and during the winter. Significant EryD were also observed in tilted body parts. Humidex Index (HI) higher than 30 °C revealed great thermal discomfort in most regions, mainly during the summer. O3amounts were generally below the thresholds established by the World Health Organization (WHO), except for two instances in which the peak of O3concentrations exceeded the 100μg m⁻³. More than 10% of chemicals sampled during the tours were identi- fied as Polycyclic Aromatic Hydrocarbons (PAH), including anthracene (peak of 207 ng per gram of air). There was a combination of EryD exceeding the MED, thermal discomfort, and PAH exposure in most studied areas. We con- cluded that this exposome could accelerate and amplify skin-related damages generally associated with a single environmental factor exposure, such as sunlight exposure at any time of the year, for example.

⁎ Corresponding author at: IRN/Unifei, Av. BPS, 1303, ZIP Code 37501151 Itajubá, MG, Brazil.

E-mail address:[email protected](M. de Paula Corrêa).

https://doi.org/10.1016/j.scitotenv.2021.146921

Contents lists available atScienceDirect

Science of the Total Environment

j o u r n a l h o m e p a g e :w w w . e l s e v i e r . c o m / l o c a t e / s c i t o t e n v

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1. Introduction

Environmental conditions, as well as lifestyle and spatial factors (population density, location's altitude), contribute to the human's exposome. A recent study listed some elements that inﬂuence skin conditions and are involved in the skin aging exposome: (i) sun radiation:

UV, visible light, and infrared, (ii) air pollution, (iii) weather factors, such as air temperature (T) and relative humidity (RH) variations, (iv) personal life factors (tobacco use, nutrition, stress, sleep), and (vi) mis- use of cosmetics products, personal care and hygiene (Krutmann et al., 2017). These environmental variables represent an important subset of the exposome that impacts several diseases' etiology, including skin cancers, eye and skin disorders, photoaging of skin, hair damage, and immune suppression (Flament et al., 2013;Dario et al., 2015;Birch- Machin and Bowman, 2016; Ivanov et al., 2018;De Vecchi et al., 2019). Thus, individuals living in sunny and polluted sites are more exposed at higher risk for metabolic problems, cancers, hair damage, and cutaneous dysfunctions, likely due to synergistic effects of UV and pollution on the skin (Soeur et al., 2017;Naudin et al., 2019). The scientiﬁc evidence involves isolated or combined effects between each of these environmental variables. However, the combined effects analysis is complex and little known, especially under ordinary and everyday conditions. In summary, as emphasized bySmith et al. (2015), the link between exposome and disease needs “a comprehensive analysis of exposure to all environmental stressors and should yield a more thor- ough understanding of chronic disease development”.

1.1. Contextualization of the study

Such exposures and the effects are highly dependent on the characteristics of the climate and population distribution. For this reason, this study focuses on everyday exposure situations in different Brazilian regions, mostly located in the tropical region.

There is sufficient evidence that UV is carcinogenic for humans, mainly for inducing squamous and basal cell carcinoma of the skin (El Ghissassi et al., 2009). Skin cancer is the most prevalent cancer in Brazil. The UV is also recognized as the major triggering factor for other harmful effects, such as premature aging of the skin, several eye and skin disorders, and hair damage (Dario et al., 2015;Birch-Machin and Bowman, 2016;Ivanov et al., 2018;De Vecchi et al., 2019). On the other hand, UV synthesizes vitamin D on the skin and it is the best natural source of this hormone. The lack of vitamin D has been associated with increased risk of autoimmune, infectious and cardiovascular diseases (Holick and Chen, 2008). However, natural vitamin D produc- tion is also associated with age, skin colour, gender, food and genetic factors. For this reason, despite geographical sunshine availability almost 20% of Brazilians show vitamin D deficiency (<30 nmol/L) or insufficiency (<50 nmol/L) (Lima-Costa et al., 2018).

The Ultraviolet Index (UVI) is an useful and dimensionless scale for the prevention damages related to the UV sunburn-producing. The higher the UVI, the greater the potential for health damage. Each UVI unit equals 25 mW m⁻²of erythemal UV irradiance (Ery), and the UVI scale varies from: low (UVI < 2), medium (UVI: 3–5), high (UVI: 6–8), very high (UVI: 8–10) and extreme (UVI > 11). Ery, in turn, is deﬁned as the spectrally wavelength-integrated UV irradiance weighted with the CIE action spectrum for the erythema (sun-induced acute redness of the skin) response of the human skin (McKinlay and Diffey, 1987).

The minimal erythemal dose (MED) necessary to induce erythema in a time interval is based on the Fitzpatrick's skin phototypes guidelines (D'Orazio et al., 2013). Lighter skin (low phototypes) transmits more radiation, and consequently the erythemal dose (EryD) necessary to induce skin redness are smaller than with darker skin (high phototypes).

Thus, we compare EryD measurements with MED to assess potential damage to skin health.

High to extreme UV levels are observed for most of the year in Brazil.

In the Northern regions, UVI reaches extreme classiﬁcation at noon

during all seasons. The Southern localities show a seasonal cycle, with very high UVI and extreme UVI during summer; and medium to high values during winter (Corrêa et al., 2003). Thus, under clear-sky conditions, short time exposures may also be harmful. Even in the presence of clouds, cumulative daily doses often exceed recommended exposure levels, even for naturally better-protected individuals (Corrêa and Pires, 2013). In addition to the natural availability of solar radiation, the Brazilian population has shown the world's fastest demographic aging worldwide (Lima-Costa et al., 2018). Consequently, epidemiolog- ical data show a continuing increase in environmental-related diseases, as vector-borne diseases and non-melanoma skin cancers, in the last 20 years. This latter became so serious that the Brazilian Society of Derma- tology has recently published new medical recommendations for photoprotection speciﬁc to such tropical conditions (Schalka et al., 2014).

Almost 85% of the Brazilian inhabitants live in urban centers where there is a high concentration of pollutants, such as PM (PM10or PM2.5, diameter less than or equal to 10 and 2.5μm, respectively) and ozone (O₃) (Carvalho et al., 2015). Brazilian policy regulations have positively impacted reducing the concentrations of primary pollutants such as carbon monoxide, sulfur dioxide, nitrous oxide, and PM10. On the other hand, concentrations of other pollutants, including VOC, PM2.5, and ul- traﬁne particles (UFP), are not yet regulated (Andrade et al., 2017).

However, according to the WHO Air Quality Guidelines, relevant concentrations of these contaminants are observed even in smaller cities (WHO, 2005). These conditions are related to trafﬁc density, street gra- dients, and enhanced by regional transport from large cities and/or bio- mass smoke (Targino et al., 2016;Krecl et al., 2016). Besides, warmer months show a greater incidence of solar radiation and could be more favorable to the O3formation. However, during the colder months, especially in the southeast Brazilian region where almost 40% of the country population lives, there is a prevalence of thermal inversions near the surface and weak winds, causing pollutants as PM2.5and O3

to accumulate (Nogueira et al., 2014;Cheng et al., 2016).

In South America, most people live in or near coastal areas where RH and T are high for most of the year. RH above 70% and monthly T averages above 25 °C are observed throughout the year, mainly in tropical areas. There are no signiﬁcant T differences between the winter and summer months. In subtropical sites, air T values show more deﬁned seasonality (Diniz et al., 2018). Despite the limitations of simplifying the personal, physiological and environmental complex processes involved in the thermal sensation, the comfort indexes provide quantitative elements for a global evaluation of the weather effects on humans (Batista et al., 2016). In general, the ambient heat perceived by humans is typically calculated using both air temperature and humidity. In this sense, the Humidex Index (HI) is a well-known quantitative index for assessing potential thermal stress (Gosling et al., 2015).Fig. 1shows the HI related to climatological data observed in four sites in Brazil:

Recife (REC), Rio de Janeiro (RIO), São Paulo (SAO), and Porto Alegre (POA). These data were provided by the National Institute of Meteorology (INMET). Human discomfort episodes (HI≥30) are usually observed during the summer season in Brazil (Dec–Feb), most evident in warmer and coastal sites such as REC and RIO. Prolonged exposure and/or physical activity under HI > 35 are related to heatstroke, heat exhaustion, and heat cramps, with HI between 30 and 35 causing fatigue for individuals during physical activity.

Assessing the daily routine exposure to these severe weather elements is necessary to evaluate their compounding impacts on human health. However, ordinary meteorological stations do not cover the ﬁne spatial and temporal grids necessary for these measurements. In this sense, portable instruments mounted on bicycles can support larger coverage areas, include areas without available data, and gather more detailed data on the everyday exposure to the weather elements (Corrêa et al., 2010;Dobbinson et al., 2016;Targino et al., 2016).

In light of the above, this study aimed to assess the environmental conditions of everyday exposure to UV, air pollution, and thermal stress

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in crowded metropolitan tropical cities. The four cities showed inFig. 1 were chosen for this study. The main reasons for selecting these cities were the high levels of UV solar radiation (Corrêa et al., 2010;Corrêa and Pires, 2013), increased numbers of episodes of thermal discomfort (Fig. 1), and because they are densely populated urban and tourist locations (De Vecchi et al., 2016). For this purpose, we have simulated typ- ical commutes to work or leisure using bicycles equipped with portable instruments. This study provides a better understanding of the co- occurrence of exposures in tropical and subtropical cities known to have effects on human health, particularly skin health.

2. Materials and methods 2.1. Study area

The study was performed in four Brazilian cities located in tropical and subtropical regions, as shown inFig. 1. The measurements were conducted on three days chosen at random in the summer and winter seasons of 2016 and 2017. Cycling routes were designed that cover touristic and urban crowded sites in tours of around 20–25 km per day. The rationale for these times of exposure related to the sum of cycling hours per city, depending on weather conditions to have enough environmental exposure, average of 2 h per day during 3 sequential days in each city.

The route maps are available onhttp://bit.ly/meteorotropicbrazil. In general, these tours were run between 30 min and 1 h30 before solar noon and ended after approximately 2 h. The distances travelled in each phase of the experiment are presented in the last column of the frame inside ofFig. 2.

2.2. Measurements

During each tour, the bicycles were mobile sampling platforms for the following measurements: erythemal UV doses (EryD), UV Index (UVI), ground-level ozone content (O3), air temperature (T), relative humidity (RH), and several chemicals. To represent the natural variation of the cyclists' movements, all data were collected every 10 s in du- plicates (two cyclists performing the same measurements). UV-related measurements were performed by Scienterra UV dosimeters (http://

scienterra.com) afﬁxed onto the cycling helmets. Five of these electronic UV dosimeters were distributed in each helmet, as shown inFig. 3. One dosimeter was installed at the top of the helmet (angle of incline ~0°), two other instruments, one on each side with an inclination angle of

~25°; and two others, one on the back (~40°) and one on the front of the helmet (~90°). These dosimeters positioned at different angles, allow estimating UV doses on inclined parts of the body. UV dosimeters were calibrated against Kipp & Zonen UV-S-AE-T radiometers, before and after each set of measurements. A 2BTech Personal Ozone Monitor was used for the O₃ samples (https://www.twobtech.com); and Instrutherm thermo-hygrometers model HTR-170 (https://www.

instrutherm.net.br) performed T and RH measurements. These instruments were afﬁxed in the basket of the bicycles. All the instruments were recently calibrated by the manufacturers.

When available, hourly averages of O3concentrations registered in sites close to the bike routes were considered to validate the experimen- tal measurements. Air quality data for RIO and SAO were provided by the Municipal Secretary of Conservation and Environment and CETESB.

REC and POA do not have available air quality data close to the bike routes. All of the continuous ambient air quality monitoring stations are mainly inﬂuenced by heavy vehicle trafﬁc. Auxiliary surface meteorological data (hourly observations of temperature and cloud cover) were provided by the Meteorology Network of the Aeronautics Com- mand website (REDEMET–http://www.redemet.aer.mil.br).

Although exposome has gained attention in the past few years, there is still no easy and/or inexpensive ways to evaluate it to include more environmental variables. In the present study, chemicals were collected by wristbands (MyExposome, Inc., Philadelphia, PA–http://www.

myexposome.com/) worn by each cyclist. MyExposome uses silicone wristbands to quantify environmental chemicals, including Polycyclic Aromatic Hydrocarbons (PAH) (Dixon et al., 2018). The participants wore the wristbands for 2 h per day on average. At the end of the sampling campaign, the wristbands were labelled and stored in air-tight conditions before analysis. Each wristband was analysed and screened for more than 1500 compounds and classiﬁed into one or more of the following categories: Chemicals in Commerce, Consumer Products, Dioxins and Furans, Flame-Retardant, Oxygenated Polycyclic Aromatic Hydrocarbons (OPAHs), Polycyclic Aromatic Hydrocarbon (PAHs), Personal Care, Pesticide, Pharmaceutical and Polychlorinated Biphenyl (Bergmann et al., 2018).

2.3. Statistics

Graphs and statistical data analyses were carried out using the Origin 2019b software package (OriginLab Inc.). General results were discussed based on basic descriptive statistics. One samplet-test test was used to evaluate thermal discomfort conditions. The statistical tests generated a 1-sided t value, andt< 0.05 represented a statistically signiﬁcant difference in compliance rates.

3. Results 3.1. UV radiation

The summer is the wet season in Southeastern Brazil, and the days are mostly cloudy. On the other hand, winters are dry with clear sky days. For this reason, most bike routes were predominantly performed under cloudiness during the hot season. Thus, UVI measurements performed in the winter were higher than those in the summer. UVI higher than 10 were only observed in some measurements performed in winter. In this season, the UVI median was approximately 3.5 in RIO, POA, and SAO and 5.3 in REC. Extreme UVI around 13 were observed in some measurements in RIO and POA. During summer, the highest UVI was observed in REC, with 6.6 and 10.0 for median and maximum values (Fig. 4).

Complementing the UV information,Table 1shows the starting and ending time, duration, distance travelled, and the accumulated EryD observed during the bike trips. The colour of the EryD cells is related to EryD that exceeds the minimal value of erythemal doses (MED) range for each different Fitzpatrick's skin phototypes guidelines (D'Orazio et al., 2013).

Fig. 1.Humidex index (HI) based on Brazilian climatological normal for T and RH averages.

Source: National Institute of Meteorology (INMET). Colored areas indicate HI degrees of discomfort: Green–HI less than 29 °C–comfortable; Yellow–HI = 30 to 39 °C–some discomfort; Orange–HI = 40 to 45 °C–Great discomfort (Masterton and Richardson, 1979).

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As explained above, cloudiness reduced the UV measurements performed in the summer. However, it is noteworthy that EryD can be suf- ﬁcient to cause erythema in phototypes V (EryD >600 Jm⁻²) and VI (EryD >1000 Jm⁻²) even on cloudy summer days. Mean (Maximum)

hourly EryD observed were 333 ± 155 Jm⁻²h⁻¹(600 Jm⁻²h⁻¹) in summer, and 340 ± 129 Jm⁻²h⁻¹(630 Jm⁻²h⁻¹) in winter. In the hot season, 42% of the hourly EryD measurements were higher than the MED for phototype III (>300 Jm⁻²). Simultaneously, in the cold season, 82% of hourly EryD was higher than MED for this same phototype.

To estimate EryD on tilted surfaces of the body, UV dosimeters were distributed on the inclined parts of the helmet.Fig. 5shows the normalized UV irradiance distribution on these tilted surfaces. Results are relative to the reference level measurements represented by the sensor at the top of the helmet (inclined measurement divided by the pseudo- horizontal measurement).

As expected, the tilted sensors' mean and median of the UVI presented lower values than the sensor in the horizontal position in most observations. However, it is worth noting that several tilted measurements are close to or even larger than those measured by the horizontal reference sensor. Almost a third of the data observed on the right and left sensors were higher than the reference. In the back and front sensors, 23.8% and 6.5% of measurements were higher than the reference values. The cumulative effect of UV exposure on a body in movement is represented inFig. 6.Fig. 5a shows the EryD measured by each sensor in each cycling route, andFig. 5b shows the relative frequencies of EryD in this set of measurements. EryD scale is shown according to Fitzpatrick's MED for each phototype (D'Orazio et al., 2013).

Fig. 2.Sites of measurements–location and population.

Fig. 3.Helmet with Scienterra UV dosimeters (white cells).

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High EryD was observed in most cases. Even to the 90° tilted sensor (front sensor), more than half of the EryD measurements were enough to cause erythema in a phototype III individual (MED > 300 Jm⁻²). In general, almost three-quarters of EryD were larger than 300 Jm⁻²in the top, left, or right sensors. In the reference sensor (top of the head–0°), EryD >600 Jm⁻²was observed in more than 55% of the data. This energy amount is enough to cause erythema in a phototype V individual.

3.2. Temperature and air humidity–Humidex index

HI measurements shown inFig. 7revealed that most of the sampling days registered some (30≤HI≤39 °C) or signiﬁcant discomfort (40≤HI

≤45 °C), especially during the summer season, except in POA (on Day 1

of summer). Despite this exception, these results show that SAO, RIO, and POA are thermally uncomfortable (one-samplet-test,t< 0.001), and REC is very uncomfortable (t < 0.001) even during the winter.

REC is located in the Northeast region, so the seasonal differences are very slight. In most southern regions, the cold season is generally more comfortable. However, ordinary events of discomfort are observed even during winter, as seen in POA.

3.3. Ozone at the ground level

O3results show values lower than those established by WHO guidelines (100μg m⁻³8-h mean) in all sites except in SAO on January 7th, 2017 and POA, on September 21st, 2017 (Fig. 8). It is important to note that our measurements do not provide 8-hour mean samples. After all, our sampling was carried out in approximately two-hour routes. For Fig. 4.UV index measurements performed during the summer (left) and winter (right)

seasons at Rio de Janeiro (red), Recife (blue), Porto Alegre (black), and São Paulo (green). In the boxplots, the lower and upper boundaries indicate the 25th and 75th percentiles, respectively. The horizontal line and the circle within the box marks are the median and mean, respectively. Whiskers above and below the box indicate the 5th and 95th percentiles, respectively.

Table 1

Erythemal doses measurements performed in each route.

St–Start time (UT), Et–End time (UT),△t–Trip duration (minutes),△S–Travelled distance (km), EryD–Erythemal Dose (Jm⁻²) measured by the reference sensor (top of the head). Colour boxes indicate EryD higher than the minimal value of erythemal doses range for different skin types using the Fitzpatrick guidelines: Phototype II–MED 250 Jm⁻²–green; III– MED > 300 Jm⁻²–yellow; IV–MED > 450 Jm⁻²–orange; V–MED > 600 Jm⁻²–red; VI–MED > 900 Jm⁻²–violet (D'Orazio et al., 2013).

Fig. 5.Normalized erythemal UV irradiance. In the boxplots, the lower and upper boundaries indicate the 25th and 75th percentiles, respectively. The horizontal line and the circle within the box marks are the median and mean, respectively. Whiskers above and below the box indicate the 5th and 95th percentiles, respectively.

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this reason, these results should be considered as estimates of peak pollution spots in urban centers. Coincidentally, both situations presented higher UV index values than the other experiment days through the city. In these episodes, mean O₃contents were 140 and 127μg m⁻³in SAO and POA, respectively. Except for SAO, mean O3contents were below 50μg m⁻³during summer. O3contents were higher in winter and are probably related to the sunniest days during this period.

We compared our biking measurements with O3measurements provided by two air quality stations (AQS) available in SAO and the other two in RIO (Table 2). Differences betweenﬁxed and mobile O₃ measurements may be due to variation in the trafﬁc emission and/or cloud cover over the region. All AQS measurements were below WHO air quality thresholds. O₃concentration range show agreement with the results presented inFig. 8, except for day 3, during Summer, in SAO. In this particular case, O3mobile results were almost twice those registered by the air quality stations Pinheiros and IPEN-USP.

3.4. Chemicals

Fig. 9shows a heatmap of the compounds found in the cyclists' wristbands. Almost 70% of compounds are commonly found in everyday personal care (32.1%), chemicals in commerce (26.8%), and consumer products (10.7%). Also present were chemicals used in pharmacological products (8.9%), pesticides (8.9%), andﬂame retardants (1.8%). There- fore, it is likely that the differences found between the samples from the same city are related to each participant's care. Interestingly, 10.7%

of chemicals were identiﬁed as PAHs, a widespread and dangerous organic pollutant derived from different sources such as fuels, smokes from automobiles, cigarettes or organic matter combustion, plastic and metallurgical industry, pesticides or dyes. InFig. 9, PAH chemicals are highlighted by an asterisk before their nomenclature.

4. Discussion

Our study has focused on environmental measurements performed around solar noon, once these are usual exposure times every day:

lunchtime, school entry and exit times, outdoor working, etc. Usual sun exposure advice would be to avoid the midday hours when the UVI is highest. However, this recommendation is generally not taken into account, and the use of photoprotection among the population is still limited. Statistics from the 21st National Campaign for the Preven- tion of Skin Cancer showed that 63% of the Brazilian population does not use any sunscreen type. Long-sleeved clothes are also not widely used because of the heat for most of the year. According to the Brazilian Society of Dermatology, 22,000 people were interviewed in this campaign conducted in December 2019 (SBD, 2020). Another mis- conception is that cloudy days offer protection from the sun. For this reason, the summer experiment was performed under cloudy conditions. Most EryD measurements performed on clear-sky days in winter were higher than those taken in the cloudy summer. However, even with the sun completely covered by cloudiness, summertime Fig. 6.Erythemal doses measurements and their relative frequencies distributions

according to Fitzpatrick's MED scale.

Fig. 7.Humidex index (°C) measurements performed during the summer (left) and winter (right) seasons at Rio de Janeiro (red), Recife (blue), Porto Alegre (black), and São Paulo (green).

Horizontal dashed lines indicate thermal comfort associated with Humidex scale: HI≤29–Comfort; 30≤HI≤39–Some discomfort; 40≤HI≤45–Great discomfort; HI > 45–Dangerous;

and HI > 54–Heat stroke imminent (Masterton and Richardson, 1979).

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measurement showed half of hourly EryD larger than MED for phototype III individuals. These data complement previous studies and reinforce the need to use any type of sun protection throughout the year in tropical/subtropical regions, including cloudy days (Corrêa et al., 2010;Corrêa and Pires, 2013).

Although radiometers and radiative transfer models provide reliable UV data, they usually show information for horizontal surfaces, so the data on tilted surfaces are generally unknown. By definition, even UVI or EryD are measured and showed for horizontal surfaces. In general, ra- diativefluxes on tilted surfaces are estimated with different geometrical models from those corresponding to a horizontal surface. These models do not allow to represent the variability of inclinations observed in a natural moving body. Thus, UVR measurements on sloping surfaces can be useful to describe the actual distribution of solar radiation on the human body. Together, these results indicated that different parts of the body, even those upright relative to the sun, receive relevant EryD in everyday situations. This kind of information is a rationale for educational campaigns for the correct use of sunscreens. After all, the incorrect use of sunscreen, use as tanning aids to avoid sunburn, insuffi- cient amounts, or the use of hats and clothes that do not cover the body adequately are results of misinformation (Neale et al., 2002;

Schalka et al., 2009;Thieden et al., 2005).

The discomfort experienced from elevated HI has an indirect impact on individuals' sun damage and skin aging. In tropical regions, the use of photoprotection can be uncomfortable because of the high temperature and humidity. Under these conditions, sunscreens tend to become oilier and more uncomfortable, and long-sleeved clothes and hats can increase heat. Several studies have shown that the use of sunscreens is generally inadequate and incorrect. The usual amounts and body distribution of the sunscreen application do not provide adequate body protection (Schalka et al., 2009;Jovanovic et al., 2017). Under thermal discomfort conditions, users describe the sunscreens as more greasy, thick, and challenging, and laborious to apply (O'Hara et al., 2019;

Schneiderbanger et al., 2019). These sensations tend to be more intense in thermally uncomfortable environments, such as the locations evaluated in this study. Thus, inhabitants of these regions may be more resis- tant to the proper use of sunscreens. As there is an exponential correlation between the applied quantity of sunscreen and its efﬁcacy (Schalka et al., 2009), the lack of sufﬁcient product application is harmful and one of the leading causes of unintended sunburn. Additionally, aggravating is that the high temperatures may contribute to skin aging as a combined deleterious effect (Krutmann et al., 2017).

Air pollution is a deleterious factor for human health. Pollutants, such as O3, PM and several PAH, can exacerbate sun-related skin damages. O₃is a secondary air pollutant at ground-level because it is formed by photochemical reactions between precursor primary pollutants, as nitrogen oxides and volatile organic compounds, in the presence of sunlight.Carvalho et al. (2015)showed higher ozone concentration values in SAO, mainly during summer and spring.Carvalho et al. (2012)also associated higher O3concentrations with higher temperatures, lower RH values, and the absence or partial cloud cover. Since most campaign days registered cloudy conditions, the O3 formation process was disfavored even during summertime, hence the lower concentration levels. Although the O3values were below the WHO's limit levels, the O₃peaks observed in some routes indicate probable local contamination by this pollutant. Along with high UVI, O3may be associated with skin aging acceleration, wrinkle and lentigines formation, antioxidants de- pletion, oxidative stress, lipid peroxidation increases, and protein oxida- tion (Krutmann et al., 2017;Parrado et al., 2019).

The presence of pollutants other than O3also attracted attention.

PAH levels were considered the primary pollution marker since there are some synergic effects between PAHs and other chemicals resulting from Brazil's extreme conditions regarding UV levels, air pollution, temperature, and humidity. These measurements are only a preliminary in- dication of the presence of these pollutants. In addition, there are no outdoor air quality guidelines for safe concentrations of these contaminants. For this reason, we cannot conclude if the levels here observed can be dangerous individually or in conjunction with other environmental variables. PAHs are thought to contribute to pigmentary disorders and extrinsic early aging. These pollutants are also associated with skin cancers, systemic toxic diseases, and acneiform eruption (Drakaki et al., 2014). Among these PAHs, signiﬁcant amounts of anthracene were found in SAO samples. This PAH has phototoxic and photoallergic action on the skin and systemic toxicity. Besides, exposure to anthracene can cause skin sensitization under sunlight and inﬂam- mation of the skin either following direct contact or after a delay of some time. Repeated exposure can cause contact dermatitis, character- ized by redness, swelling, and blistering (EPA, 1987;SCHER, 2006). Our Fig. 8.Surface ozone concentration (μg m⁻³) measurements performed during the summer (left) and winter (right) seasons at Rio de Janeiro (red), Recife (blue), Porto Alegre (black), and São Paulo (green).

Table 2

Maximum 8-hour average O3concentration (μg m⁻³) registered close to the cycling routes during summer and winter experiments in Rio de Janeiro and São Paulo–O3level threshold established by WHO: 100μg m⁻³8-hour mean.

City Sites Summer Winter

Day 1 Day 2 Day 3 Day 1 Day 2 Day 3

Rio de Janeiro Centro 28.4 31.3 48.3 44.7 49.5 64.0

Copacabana 30.0 28.8 35.3 39.5 35.5 46.2

São Paulo Pinheiros 73.1 54.9 86.0 59.4 79.9 82.0

IPEN-USP 60.4 46.6 76.8 52.3 70.6 69.4

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measurements showed that the amounts of anthracene found are high enough to cause skin damage. However, it is important to note that our study is limited to a comprehensive analysis of several environmental exposures, and we could not provide additional information on how this combination of exposures induce or accelerate chronic or acute skin diseases progression. Thus, further investigations are needed to better understand the impacts caused by the presence of anthracene and other PAHs in urban sites.

5. Conclusions

This study presented a set of environmental parameters measurements related to human health. The use of cyclists as mobile platforms increased the spatial and temporal gain of the measures. For this reason, this method is recommended to obtain valuable information on the combination of environmental exposures experienced during everyday life. Ourﬁndings conﬁrm the presence of high UV levels observed in tropical and sub-tropical areas, inclusive of cloudy days and the wintertime. The well-known deleterious effects of UV overexposure can also be potentiated by the regional extrinsic exposomes: air pollution and thermal discomfort.

Previous studies have shown that summer EryD in Brazil can be several times higher than those observed in this study (Corrêa et al., 2003;

Corrêa and Pires, 2013;Schalka et al., 2014). Signiﬁcant EryD were also observed at the horizontal surfaces and the tilted sensors distributed throughout the helmet of the cyclists. This shows that the accumulated EryD can be high in any part of the body. Long-term exposures under these UV conditions are potentially harmful to human health, mainly skin, hair, eyes, and immune system.

The daily use of photoprotection is strongly recommended in these situations. However, the combination of high air temperatures and high relative humidity made the environment thermally uncomfortable in all evaluated sites, mainly during the summer. In these conditions, long sleeve clothing and the use of sunscreens can be uncomfortable on the skin, and its application and reapplication can be tedious (Schneiderbanger et al., 2019). The sum of these factors is a negative scenario for the health of populations in tropical sites with higher UV, T, and RH.

In addition to these effects, several studies highlight the health damages caused and combined with air pollution. O3, PAHs, and particulate matter are viewed as the most damaging pollutants. The latter was not

evaluated in this study. In most samplings, O3concentrations were below the thresholds established by WHO. The shift from ethanol to gasoline use in Brazil is identiﬁed as the main factor responsible for reducing local O3levels in urban areas as SAO (Salvo and Geiger, 2014).

However, as observed in two sampling days, high O3concentrations still represent the main air pollution problem in urban sites as SAO and POA (Alvim et al., 2017). Concerning chemicals, most of the compounds found in the wristbands were substances derived from personal care, commercial, and consumer products. However, PAHs represent 10% of the detected chemicals. Signiﬁcant amounts of anthracene, a potential skin photo-toxigenic, and photo-allergenic, were found in SAO.

The presence of substantial amounts of PAH in the study sites strongly contributes to situations of potential damage to human health.

The combination of high UV levels, thermal discomfort, and the presence of relevant amounts of O3and PAHs constitute an unfavorable exposome to inhabitants' health of the tropical and subtropical regions.

We reinforce the recommendation for using sunscreens, sunglasses, hats, and t-shirts in these regions of Brazil. In the case of sunscreens, spe- ciﬁc formulae that minimize the air pollution effects are necessary. These sunscreens should also be sturdy and comfortable enough for being used under high temperature and humidity conditions. The same recommendation should be applied to clothing fabrics, as they must be composed ofﬁbers that protect from the sun and minimize the sensation of heat. Fi- nally, further studies on the long-term effects of exposure to this exposome and the combined effects of PAHs' presence are needed.

Credit authorship contribution statement

All the authors contributed to the research. MP Corrêa: Conceptual- ization, Methodology, Investigation, Writing - Review & Editing. AG Marciano, PM Bernardo and R DeVecchi: Investigation and Data Curation. VSB Carvalho, JSC Ripper, D Roy and L Breton: Investigation, Writing - Review & Editing.

Declaration of competing interest

The authors declare the following ﬁnancial interests/personal relationships which may be considered as potential competing interests: Rodrigo De Vecchi, Júlia da Silveira Carvalho Ripper, Daniel Roy and Lionel Breton are employees of L'Oréal Research & Innovation.

The remaining authors have received sponsored research support from Fig. 9.Left side: Heatmap of the chemicals found in the wristbands [in ng of chemicals per g of wristband sample] -“*”symbol indicates PAH chemicals. Right side: Chemicals classiﬁcation:

CiC - Chemicals in Commerce; CP - Consumer Products; FR - Flame Retardant; PAH - Polycyclic Aromatic Hydrocarbons; PC - Personal Care; Ph - Pharmacological; Ps–Pesticide.

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L'Oréal Research & Innovation. However, the authors declare that the research was conducted in the absence of any commercial orﬁnancial relationships that could be construed as a potential conﬂict of interest.

Acknowledgments

We thank the staff of MyExposome, Inc. for the quantitative analysis of pollutants. The authors also wish to thank Juliana Amado Martins, Ana Raquel Monteiro, and Wagner Pereira for all support during the ex- perimental campaigns. This work was supported by L'Oréal Research &

Innovation. Dr. Corrêa thanks Conselho Nacional de Desenvolvimento Cientíﬁco e Tecnológico [CNPq, grant 304701/2016-5] and Fundação de Amparo à Pesquisa do Estado de Minas Gerais [FAPEMIG, grant PPM-00439-16].

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