ITLI20010010A1 - MULTI-USER APPARATUS FOR REAL TIME MEASUREMENT AND REMOTE CONTROL OF THE SOLAR ULTRAVIOLET RADIATION DOSE. - Google Patents

Description

Description of the industrial invention entitled:

"MULTI-USER DEVICE FOR MEASURING AND REMOTE CONTROL IN REAL TIME OF THE DOSE OF SOLAR ULTRAVIOLET RADIATION"

SUMMARY

The invention is part of the field of methods and equipment used for measuring and controlling the dose of UV radiation in relation to the photodermatological effects of human skin. More specifically, the invention is directed to a family of apparatuses to be used in the tourism sector for the protection of the health of the tourist (eg bather) who is exposed to solar radiation at least as regards the prevention of solar erythema.

The dose of solar ultraviolet (UV) radiation for a given event of exposure of the person is a critical parameter for his health as various dermatological effects are linked to it, such as the onset of erythema. If considered in the long term, both the number of burns (erythema) and the amount of the cumulative UV dose taken are related to the probability of the onset of skin cancers of different types and in any case to the loss of skin elasticity.

At present, portable physical (broadband radiometers) or chemical (photosensitive patches) dosimeters are used for the prevention of solar erythema, or, in some countries, information and advice related to estimates of solar UV radiation (e.g. UV index ) present or scheduled for local midday.

In the first case, the user must purchase the dosimeter and face the problem of programming the dosimeter in the physical case or of choosing the most appropriate degree of photosensitivity in the chemical case, according to the UV photosensitivity characteristics of his own skin.

On the other hand, in the case of information related to the UV index, both the information regarding the level of radiation and the consequent recommended rules of behavior are often too general (not personalized) and inadequate to enable the user to enjoy the radiation with serenity. solar.

The system aims to provide simultaneously to different users who expose themselves to the sun, a control service of the effective erythemic UV dose accumulated by each of them starting from a given specific instant, characterizing the photosensitivity of each user before exposure. (minimum erythemic dose - MED), measuring these doses in real time, taking into account any changes in the environmental UV irradiation conditions and in particular allowing each user to know the dose accumulated up to that moment and to compare it with a specific critical safety value (threshold) assigned to the user himself.

The minimum erythemic dose (MED) on the basis of which it is possible to establish the threshold value of the critical dose that can be taken, is determined before the exposure event by means of an expert system based on photodermatological history and / or analysis of some optical properties of the skin of the user. The system is therefore able to measure the dose accumulated by each user (customized dosimeter function) and to adjust its entity starting from the instant in which he began to expose himself to solar radiation, taking into account the erythemic UV dose. integral which he actually accumulated starting from that instant.

This method, based on the real-time measurement of the erythemic UV dose, allows to automatically and directly take into account the dose taken by each user, resulting from the contribution of the different levels of UV radiation that reach the user during the course of his exposure (e.g. example related to variations in atmospheric conditions, stratospheric ozone layer, tropospheric pollution, zenith angle of the sun, surface albedo, ..).

The system is also able to determine and communicate this dose to the user before exposure and in particular to enable the user to check the UV dose value at any time during the exposure, even in remote locations. accumulated through one or more means of communication (luminous display, signal on remote user terminal, ...). Each user can also be personally notified with a personalized message of the imminent achievement of their erythemic dose threshold, allowing them to end exposure to the sun, avoiding at least the erythemic effects induced by an excessive dose of ultraviolet solar radiation.

In particular, the system is able to monitor the dose taken for two different modes of skin exposure:

- skin area exposed parallel to the local horizontal plane (global horizontal solar radiation)

- skin area normally exposed to the direction identified by the solar disk (normal global solar radiation)

This difference is particularly important in the case of clear skies in the absence of haze or clouds and for intermediate solar zenith angles (e.g. 25-40 degrees), and its importance is documented by the fact that reddening is typical. (erythema) of the skin in correspondence with some parts of the body rather than in others (eg shoulders, ankles), during exposure of the body when the atmosphere is particularly clear.

The accumulated UV erythemic dose is measured also taking into account the possible presence of UV photoprotective agents applied to the user's skin, evaluating the filtering power of these products according to the standards used nationally and internationally (eg. COLIPA, FDA, [7 ], [8]).

The system is also able to predict the UV index value (UV index defined by the World Meteorological Organization) at local solar noon if the present weather conditions remain stationary.

Finally, the system is able to provide the user, before the start of the exposure, with an approximate estimate of the length of the exposure time interval linked to the safety dose set and starting from a given starting instant. exposure set, predicting in particular what the erythemic irradiance will be during the exposure interval, according to the variation of the position of the sun with respect to the geographical location in which the user is located, in the case of constant current weather conditions and / or taking into account the most risky case, in which the meteorological conditions are those of clear skies. In the drawings:

- fig. 1 illustrates a table of phototypes traditionally used according to the DIN-5050 standard;

- fig. 2 shows the erythemic action spectrum for human skin according to the CIE international standard;

- fig. 3 schematically shows the implementation of a system configuration according to the invention.

DESCRIPTION

In a preferred embodiment, the system consists at least of the following modules:

A. Expert system module

Determines the value of minimum erythemic dose (MED) characteristic of a given user through a questionnaire with specific history for photodermatology and / or on the basis of one or more measures relating to the optical properties of the skin related to reflection and / or backscatter of the electromagnetic radiation in the visible and / or infrared spectrum emitted by one or more sources.

The MED value can be determined before each exposure taking into account the constitutive and optional photoprotective conditions of the user.

B. Solar erythemic effective irradiance measurement module

This module aims to measure the solar irradiance responsible for the erythemic effect of human skin.

The module therefore provides instant measurement of the effective erythemic irradiance of solar radiation, according to the erythemic action spectrum for human skin.

This module provides at least the horizontal global irradiance, and possibly also the normal global one, or provides data from which this / these irradiations are indirectly deductible (eg from satellite data dedicated to the observation of the earth and the atmosphere).

C. Central module

This unit performs at least the following operations:

1) acquires the minimum erythemic dose (MED) specific to the user in the conditions in which he is just before the exposure, from another external unit (for example, remote external expert system connected electronically), or directly from other sources that have this data (e.g. user himself via the terminal), or finally determining it himself (in the latter case by incorporating in itself the expert system module A. or part of it)

2) acquires continuously in real time directly from module B. the measurement of the effective erythemic irradiance and / or obtains continuously indirectly from such data and / or from other available data (e.g. from satellite data analysis via telematic network) instantaneous values of effective erythemic horizontal global irradiance and / or effective erythemic normal global irradiance relative to the locality in which the service is provided

3) measures in real time the effective erythemic dose associated with a given instant of start-up of the service (e.g. local sunrise time) and the acquired data of effective erythemic horizontal global irradiance and / or effective normal erythemic global irradiance

4) measure in real time for each user, the effective erythemic dose associated with a given instant of exposure start of the single user and the acquired data of effective erythemic horizontal global irradiance and / or effective erythemic normal global irradiance

5) manages the real-time presentation of the following data on the information panel:

to. data relating to the erythemic dose referred to in point 3) starting from the start-up time

and possibly of:

b. data relating to the irradiance referred to in point 2)

c. for each user, the estimate of the residual exposure time to reach the critical erythemic dose linked to the MED referred to in point 1)

The Central module can also perform the following functions:

6) for each user before the exposure begins, it provides a preliminary estimate of the optimal exposure times, in the approximation of constant meteorological conditions and / or the most critical case of clear skies, taking into account at least the following parameters in the algorithms calculation:

a) the user's minimum erythemic dose (MED)

b) date and time when the user's exposure should begin c) geographical coordinates of the place

d) temporal evolution of the position of the sun relative to the geographical location in question (zenith angle and possibly azimuth for non-isotropic UV sensors)

e) any protection factor (SPF) of the photoprotective agent applied by the user according to standard conditions and defined according to international standards (eg COLIPA and FDA [7] and [8]). f) effective global erythemic horizontal irradiance and / or effective global normal erythemic irradiance of the present moment g) horizontal and / or normal global effective erythemic UV irradiance expected for each future instant during exposure in the case of stationary weather conditions

and / or alternatively to (f) and (g)

h) horizontal and / or normal global effective erythemic UV irradiance expected for each future instant during exposure in the case of clear weather conditions associated with one or more factors such as:

local stratospheric ozone level

local aerosol level

local air humidity level

local concentrations of tropospheric pollutants

UV receptivity of the local soil (albedo)

altitude of the place

7) for each user before the exposure begins, provides the estimate of the protection factor (SPF) of the photoprotective substance to be applied to the user's skin under standard conditions, according to the following parameters, assuming current weather conditions and / or in the most critical hypothesis of clear skies:

to. minimum erythemic dose (MED) of the user

b. date and time when user exposure should begin c. geographical coordinates of the place

d. time interval of duration of the desired exposure (limited to a maximum safety value that can be set) e. temporal evolution of the position of the sun relative to the geographical location in question (zenith angle and possibly azimuth for non-isotropic sensors)

f. effective erythemic horizontal global irradiance and / or present moment effective erythemic normal global irradiance g. horizontal and normal global effective erythemic UV irradiance expected for each future instant during exposure in the case of stationary weather conditions

and / or as an alternative to f. and g.

h. horizontal and normal global effective erythemic UV irradiance expected for each future instant during exposure in the case of clear weather conditions associated with one or more of the following factors:

local stratospheric ozone level

local aerosol level

humidity level of the local alpha

local concentrations of tropospheric pollutants

UV reflectivity of the local soil (albedo)

altitude of the place

8) manages in real time for each user the start / stop display signals, and possibly the start and / or stop signal generated by the remote user terminal if there is a bidirectional link. D. User data submission form

It makes the following data visible, directly from the place where users are exposed to the sun and in real time:

• data relating to the erythemic dose referred to in point C.3 starting from the service start-up time

and possibly also the following data:

• data relating to the irradiance referred to in point C.2

• for each user, the estimate of the residual exposure time to reach the critical erythemic dose linked to the MED referred to in point C.1

The system can possibly be equipped with the following accessory modules:

E. User remote terminal link management module

This unit manages the data transmission from the central module of the system to each user and, if the link is of the bidirectional type, the reception by each user equipped with a remote terminal of at least the signals relating to the start event and / or stop of exposure.

F. Remote user terminal

This device, uniquely assigned to each user, manages the reception and possibly the transmission to the system of at least the signaling relating to the start and / or stop event of the user's exposure to solar radiation.

The E-F link can possibly also be used to exchange other types of information between the central unit and users and be implemented in any way (radio frequency link, telematic link, telephone link, ...) in a unidirectional or bidirectional way.

In addition, all functions with the exception of function C. 3 and C. 5. a can be performed by each remote user terminal informed of the necessary data by the central module C. through the link E.-F.

Characteristic algorithms

The device in its various modules uses the following measurement and calculation methods:

A. Expert system module

Determination of the user's minimum erythemic dose (MED) using the correlation algorithm of this user-specific parameter with the data acquired in the following ways:

1) Data from questionnaire (photodermatological history)

The questionnaire requires at least characteristic data of the user's phenotype, their habits and experiences found in relation to past exposure of their skin to solar radiation. For example see [1] and [2],

2) Data from an optical or opto-electronic instrument that exploits the visible and / or infrared electromagnetic radiation emitted by one or more sources and provides data according to the measurements of the reflected and / or backscattered radiation from the skin and the radiation emitted by the source incident on the skin

The optical instrument can exploit the light reflected directly from the skin (eg skin colorimetry) or the backscattered radiation from the different layers of the skin (eg skin spectrophotometry) for one or more wavelengths.

3) integration of data from the aforementioned methods' 1) and 2)

B. Solar erythemic effective irradiance measurement module

This module must at least provide the horizontal effective global erythemic irradiance, and possibly also the normal global one or data from which this / these quantities are indirectly deductible (eg data from earth observation satellites). For this purpose, the module can possibly be equipped with more sensors (eg "shadow-band" spectroradiometer) to measure directly or indirectly obtain the different components of the solar radiation necessary for the calculation, possibly also using the information on the angle of solar zenith z, calculated on the basis of geographic coordinates and local date and time.

Figure 2 shows an example of an erythemic action spectrum, defined between 280 and 400 nm.

The module can exploit both meters based on broadband sensors (eg Yankee Environmental Systems Model UVB-1 Pyranometer) or spectroradiometers with Lambertian response (eg Glen Spectra Ltd. OL754-PMT), whose measurement is then used according to the following formula for determining the effective erythemic irradiance:

where is it:

λ indicates the wavelength

t indicates time

effective erythemic irradiance at time t (e.g. W / m2)

spectral irradiance measured by the spectroradiometer (eg.

W / (m2 * nm)); = erythemic action spectrum (e.g. CIE erythemic action spectrum) Finally, the module can provide characteristic data of the atmosphere (e.g. stratospheric ozone layer, characteristics of the clouds present, aerosols, water vapor, ...) to allow indirect estimation of the irradiance values through appropriate calculations (eg radiative transfer models). Furthermore, the measurement must in any case respect the angular dependence on the direction of the incident radiation of the human skin which is of the Lambertian type (cosine response). ; C. Central module; The central module performs the following operations:; 1) acquisition and / or calculation of:; a) horizontal global effective erythemic irradiance Gh and possibly global normal effective erythemic irradiance Gn This parameter can be directly acquired or calculated on the basis of data provided by the measurement module B. and / or calculated indirectly by the central module using data from other sources (eg satellite data) based on calculation models (eg radiative transfer models). ; 2) calculation of the effective erythemic dose starting from an instant of start-up tstartup; a) horizontal global effective erythemic dose; The calculation of this dose at instant t> tstartup takes place according to the following formula: ;;; ;; b) normal overall effective erythemic dose; The calculation of this dose at instant t> tstartup takes place according to the following formula: ;;; ;; 3) calculation of the effective erythemic dose starting from a given instant tstartj associated with the i-th user; The calculation of this dose takes place for the i-th user according to the same formulas described in point 2), where the integral instead of from the start-up instant it is calculated starting from tstartj. ; 4) management of the start and stop signal for user i-th exposure; The management of the start signal (tstart,) can take place immediately or in a delayed manner, possibly on the basis of a signal received from the central module coming from the user according to any channel (e.g. bidirectional link for central module and user terminal). ; The generation of stop signals by the central module occurs instantly when at least one of the following critical dose conditions and therefore alarm occurs: ;; ;; where Kh, and Knj are two dimensionless constants less than or equal to 1, definable according to different security criteria and possibly customized for each user, and MED, represents the minimum erythemic dose characteristic of the i-th user. ; The stop signs for each user can also be more than one, reporting to the user different levels of security in the display. ; It should be noted that these signals are not directly correlated to the instantaneous UV radiation level (irradiance), which can therefore assume any value during user exposure (e.g. variations due to weather conditions), but rather to the dose of energy accumulated starting from tstart,. ; The stop signal can possibly also be generated by the user before having taken the entire safety dose and this signal can then be received by the central module which eventually records and manages this event (e.g. temporary pause of the exposure ). ; 5) Acquisition and presentation to the i-th user of the MED and of the accumulated dose starting from t = startup; The MED of the i-th user is acquired from the expert system module and the critical dose value DoseStop_ is provided to the user by any means of communication before the exhibition begins. ; The value of the accumulated dose from the start-up instant (in any case prior to any tstartj for any user i) is updated in real time on the user data submission form. ; In this way the DoseStop_ critical dose value, provided to the user in the same units of measurement with which the accumulated dose is calculated and supplied starting from startup, can be used by the user to check how much dose he has accumulated starting from tstartj in the following way:; • at instant tstartj, when the i-th user starts the exposure, he knows from the data submission module the accumulated dose value up to that instant starting from tstartup (DoseStartup (tstarti)) ; • at any time after tstartj the user can calculate the dose accumulated by him starting from tstartj according to the following relationship:; Dose (t) = DoseStartup (t) - DoseStartup (tstartj); therefore, knowing his own critical dose (eg. DoseStop_ =; he can check at any moment t> tstarti if he has already taken his critical dose or if he can still remain exposed to the sun to reach it, by comparing the values of Dose (t) and DoseStop_. ; If the user has a user terminal in which some functions performed by the Central C module have been transferred, and has received the critical dose value, the value of tstarti and receives the instantaneous DoseStartup (t) value from this module, it can itself provide the user with information on the residual dose. ; If it also receives the effective erythemic irradiance value, it can calculate and provide the user with an estimate of the time remaining to take his own critical dose, based on algorithm 6) or its simplified equivalent. ; 6) Estimation of the exposure time for the i-th user; In order to give the user an indication of the exposure times associated with the critical doses of effective erythemic radiation, the following estimates can be made:; a. Time required for the i-th user to take a critical dose starting from an assigned instant (tstartj) in stationary weather conditions; Input data; - MED,: minimum erythemic dose characteristic of the i-th user - Khj safety factor ; - IrrGh (to): global effective horizontal erythemic UV irradiance at the present moment; - (Lat, Lng, Alt): local geographic coordinates such as latitude, longitude, altitude; - to: date and time (defined at least up to the minute) of the present moment; - tstartj: date and time (defined at least up to the minute) when the user should start exposure; - SPF: value of the protection factor of the photoprotective agent possibly applied to the user's skin in quantity and standard conditions; Algorithm; - Calculation of the zenith angle (and possibly of the solar azimuth) ;; See for example [6]; - Calculation of the horizontal effective global erythemic UV irradiance irradiance at instant t> to ;; ;;; where is a function that; expresses the fraction of the maximum horizontal global irradiance obtainable in conditions of the sun at the zenith in the meteorological conditions relating to time t0, as a function of the zenith angle SZA. ; - Calculation of the tstop instant, expected in which the dose will be accumulated; The time t> tstarti for which the dose is expected to have been taken horizontally Dose (t) satisfies the following relationship: ;; ; By calculating the above integral for increasing t> tstartj, the tstopi time for which the dose will be taken DoseGhj ;;; ;;; will therefore result from the first value of t for which; the following identity will be found verified:; b. Time required for the i-th user to take a dose; starting from an assigned instant (tstartj) in stationary weather conditions; Input data; As case a. previous where instead of IrrGh (t0) is given IrrGn (t0) effective global erythemic UV irradiance normal at the present time and instead of the safety coefficient for global horizontal radiation the coefficient relative to global normal radiation is given. ; Algorithm; As case in case a. previous where instead of instead of ;; a similar function is used which; which expresses the fraction of the maximum normal global irradiance obtainable in conditions of the sun at the zenith in the meteorological conditions relating to time to, as a function of the zenith angle SZA. ; c. Time required for the i-th user to take a dose; starting from an instant assigned in clear sky conditions; Input data; - MEDj: minimum erythemic dose characteristic of the i-th user - Safety coefficient; - (Lat, Lng, Alt): local geographic coordinates such as latitude, longitude, altitude; - tstarti: date and time (defined at least up to the minute) in which the exposure should begin; - SPF: value of the protection factor of the photoprotective agent possibly applied to the user's skin in standard quantities and conditions; - 03: current value, typical for clear skies and time of year or minimum of the local stratospheric ozone level; - Aer: current value, typical for clear skies and time of year or minimum local aerosol level; - H20: current value, typical for clear skies and time of year or minimum local air humidity level; - Trop: current value, typical for clear skies and time of year of the concentrations of tropospheric pollutants with absorption spectrum in the ultraviolet; - R: estimated or measured UV reflectivity of the local soil (albedo) Algorithm; - Calculation of the zenith angle (and possibly of the solar azimuth); ; See for example [6]; - Calculation of the horizontal global spectral irradiance; Any clear-sky radiative transfer algorithm is used that provides the horizontal global spectral irradiance data at least in the spectral window in which the erythemic action spectrum is defined , Such as ;;; ;; Calculation of the horizontal global effective erythemic irradiance The horizontal global effective erythemic irradiance at time is calculated from the following formula: ;; where:; λ: wavelength; wavelengths for which the considered action spectrum is defined; t: time; = horizontal global erythemic irradiance effective at time t; = spectral irradiance calculated for time t e; wavelength λ; = erythemic action spectrum (e.g. Diffey spectrum - CIE) - Calculation of the instant tstop, predicted in which the dose DoseGhj will be accumulated; The time t> tstart, for which the dose is expected to have been taken horizontally Dose (t) satisfies the following relationship:; ;; By calculating the above integral for t> tstart, increasing, the; tstopi time for which the dose will have been taken ;; it will therefore result from the first value of t for which the; following identity 'will be found' verified: ;;; ;; d. Time required for the i-th user to take a dose starting from an assigned instant in clear sky conditions; Input data; Identical to those of the previous case C.; Algorithm; Identical to that of case c. previous, with the exception of the fact that instead of calculating the global horizontal spectral irradiance, the calculation of the global normal spectral irradiance is performed and the safety coefficient relative to the global normal radiation is used. ; 7) Estimation of the photoprotection factor for the i-th user; In order to favor the permanence in the presence of solar radiation, especially for users who are characterized by relatively small MED values, the system can 'offer the possibility' of estimate the optimal protection factor of the cream (SPF) in relation to the expected exposure time starting from a given instant. ; Input data; -: minimum erythemic dose characteristic of the i-th user - Safety coefficient ;; - global effective horizontal erythemic UV irradiance at the present moment; - (Lat, Lng, Alt): local geographic coordinates such as latitude, longitude, altitude; - to 'date and time (defined at least up to the minute) of the present moment; - tstartj : date and time (defined at least up to the minute) in which the exposure should begin; - Etime: time interval of duration of the desired exposure (limited to a maximum that can be set for safety); - SPF: value of the protection factor of the photoprotective agent possibly applied to the user's skin in standard quantities and conditions; Algorithm; Case in which it refers to the global radiation incident on the horizontal plane in stationary meteorological conditions - ref 4. a. previous:; - Calculation of the zenith angle (and possibly the solar azimuth) ;; See for example [6]; - Calculation of the instantaneous global effective horizontal erythemic UV irradiance irradiance; ;;; where it is a function that; expresses the fraction of the maximum global horizontal irradiance obtainable in conditions of the sun at zenith in; meteorological conditions relating to time as; function of the zenith angle SZA. ; - Calculation of the accumulated dose in the Etime time interval, starting from time tstartj ;;; ;;; - Calculation of the theoretical SPF photoprotective factor such that the i-th user takes a dose equal to khi * MEDi

For security reasons, the SPF number provided in output is defined as the first integer greater than the real number obtained from the theoretical formula.

For other cases of:

normal global erythemic irradiance in stationary weather conditions horizontal global erythemic irradiance in clear sky conditions normal global erythemic irradiance in clear sky conditions using the same principle and the calculation methods extracted from points 4b. , 4c. and 4d. described above, it is possible in a completely analogous way to provide the estimate of the respective SPF factor.

The calculated value refers to the standard conditions of use for which the SPF factor is defined (eg quantity of photoprotective product of 2 mg / cm2) defined in [7] and [8].

8) Forecast of the UV Index (UV index) for local solar noon in stationary weather conditions

The system is able to predict, assuming that the weather conditions remain stationary, the UV index value for local midday. Input data

: global effective erythemic UV irradiance horizontal al

present moment

- (Lat, Lng, Alt): local geographic coordinates such as latitude, longitude, altitude

- date and time (defined at least up to the minute) of the moment

here I'm

Algorithm

- Calculation of the maximum zenith angle and the local noon time (and possibly the solar azimuth)

which gives SZA_max = SZA (t_mday) and the value d

- Calculation of the horizontal effective global erythemic UV irradiance irradiance at the instant t_mday of local midday

where is a function that

expresses the fraction of the maximum global horizontal irradiance obtainable in conditions of the sun at the zenith in the meteorological conditions relating to time t0, as a function of the zenith angle SZA.

- Conversion of the horizontal global effective erythemic irradiance into UV Index units of measurement according to the international WMO standard used.

Examples of devices for the realization of the system

Central module:

Personal Computer or website with dedicated SW applications, including the algorithms described and possibly the expert system or part of it, and peripherals for interfacing with the other system components

UV irradiance measurement module:

Yankee Environmental Systems (USA)

Model UVB-1 Pyranometer sensor

Optoelectronic device for expert system:

Minolta (JP)

CR-200 tristimulus colorimeter

Event management system start / stop user exposure:

Multichannel radio frequency transceiver system (e.g. SMS message management system in real time)

Remote user terminals:

Radio frequency transceiver device or internet terminal (e.g. mobile phone enabled for receiving / sending SMS messages in real time or GPRS mobile phone)

Claims (1)

CLAIMS 1. Multi-user apparatus for real-time measurement and control of the solar ultraviolet radiation dose taken by one or more users, comprising: - at least one module for direct or indirect UV irradiance measurement; - at least one central module for the acquisition and / or continuous calculation in real time of the effective erythemic dose accumulated starting from a given instant tstart and of the minimum effective erythemic dose (MED) associated with the i-th user; - means for reporting in real time to each user the value of the residual dose before reaching a predetermined threshold, linked to the user's specific MED value; - in which said measuring modules, central module and signaling means are in reciprocal communication 2. Apparatus according to claim 1, comprising means for storing and communicating to said central module the minimum erythemic dose (MED) characteristic of the user for calculating the effective erythemic dose threshold to be attributed to it. 3. Apparatus according to claim 2, comprising an expert system capable of determining the MED value of each user and communicating it to the central module, possibly also taking into account its history of exposure to solar radiation. 4. Apparatus according to claim 3, wherein said expert system comprises a dermatological anamnesis for determining the MED of one or more users and sending the characteristic data relating to said central module for calculating the effective erythemic dose threshold to be attributed to each user. 5. Apparatus according to claim 3, wherein said expert system comprises an optoelectronic device for characterizing the skin of one or more users and sending the characteristic data relating to said central module for calculating the effective erythemic dose threshold to be attributed to each. Apparatus according to one or more of the preceding claims, wherein said central module comprises means for the continuous estimation of the residual exposure time associated with the residual effective erythemic dose for one or more users and means for signaling said residual time to them. 7. Apparatus according to one or more of the preceding claims, wherein said central module comprises communication means for allowing each user to determine the accumulated dose at any instant starting from a given time tstarti, by difference between the value of a counter reference dose at time tstarti and the present value of the counter, being the dose expressed in the same units of measurement used for the erythemic dose threshold characteristic of the user. 8. Apparatus according to claim 7, wherein said signaling means comprise a signaling panel of the data relating to the accumulation of effective erythemic dose. 9. Apparatus according to claim 1, wherein said signaling means comprise at least one multi-channel radio frequency transceiver system, for the transmission of data to one or more remote user terminals. 10. Apparatus according to claim 9, comprising at least a radio frequency transceiver device or a terminal enabled for communication via the Internet, preferably a mobile phone enabled for receiving / sending SMS messages in real time or a mobile phone enabled for connection to a telematic network (eg internet ). 11. Apparatus according to claim 1, wherein said central module comprises means for managing start / stop user exposure events. 12. Apparatus according to claim 1, in which said module for measuring the effective erythemic UV irradiance is constituted by a satellite data processing center; said central module consists of a service center on the internet telematic network; said means of signaling the value of the residual dose consist of a telematic network (e.g. internet) of remote user terminals, through which each user can communicate their geographical coordinates to the central module (e.g. via GPS system integrated in the mobile phone) . 13. Apparatus according to claim 12, wherein said remote user terminals allow the user to communicate with the central module in order to interact with the expert system for determining their MED.