Earth's Ozone Research Articles

Exploring the link between ultraviolet B radiation and immune function in amphibians: implications for emerging infectious diseases

Amphibian populations the world over are under threat of extinction, with as many as 40% of assessed species listed as threatened under IUCN Red List criteria (a significantly higher proportion than other vertebrate group). Amongst the key threats to amphibian species is the emergence of novel infectious diseases, which have been implicated in the catastrophic amphibian population declines and extinctions seen in many parts of the world. The recent emergence of these diseases coincides with increased ambient levels of ultraviolet B radiation (UVBR) due to anthropogenic thinning of the Earth's protective ozone layer, raising questions about potential interactions between UVBR exposure and disease in amphibians. While reasonably well documented in other vertebrate groups (particularly mammals), the immunosuppressive capacity of UVBR and the potential for it to influence disease outcomes has been largely overlooked in amphibians. Herein, we review the evidence for UVBR-associated immune system disruption in amphibians and identify a number of direct and indirect pathways through which UVBR may influence immune function and disease susceptibility in amphibians. By exploring the physiological mechanisms through which UVBR may affect host immune function, we demonstrate how ambient UVBR could increase amphibian susceptibility to disease. We conclude by discussing the potential implications of elevated UVBR for inter and intraspecific differences in disease dynamics and discuss how future research in this field may be directed to improve our understanding of the role that UVBR plays in amphibian immune function.

Astronomy: Ozone-like layer in an exoplanet atmosphere.

The nature of exoplanetary atmospheres is hotly debated. The thermal spectrum of an exoplanet called a hot Jupiter reveals the presence of an analogue of Earth's ozone layer, although its composition is unknown. See Letter p.58 Earth's atmosphere consists of layers that are partially defined by their temperature. In the troposphere, which is just above the Earth's surface, temperature decreases with altitude, whereas the layer above, the stratosphere, is warmer. Exoplanets could also have stratospheres, but whether they actually do has been an open question. One way to find out is to observe whether molecular species are seen in emission in the planet's thermal spectrum, which would indicate that the overlying layer is hotter than the lower one. Tom Evans et al. report observations of the gas-giant exoplanet WASP-121b, which reveal emission lines of water, from which they conclude that the planet has a stratosphere.

Improved measurements of atmospheric nitrous oxide

Nitrous oxide (N2O), one of the main greenhouse gases, is known for its degrading effect on Earth's ozone layer. The gas is created naturally by microbial activity on land and in the oceans and artificially by emissions from human‐made processes, through fertilization or burning fossil fuels. As the climate continues to warm, it has become imperative to be able to track and quantify the greenhouse gas content of the atmosphere, and various satellite missions have been launched to do so.

Impact of a potential 21st century “grand solar minimum” on surface temperatures and stratospheric ozone

We investigate the effects of a recently proposed 21st century Dalton minimum like decline of solar activity on the evolution of Earth's climate and ozone layer. Three sets of two member ensemble simulations, radiatively forced by a midlevel emission scenario (Intergovernmental Panel on Climate Change RCP4.5), are performed with the atmosphere‐ocean chemistry‐climate model AOCCM SOCOL3‐MPIOM, one with constant solar activity, the other two with reduced solar activity and different strength of the solar irradiance forcing. A future grand solar minimum will reduce the global mean surface warming of 2 K between 1986–2005 and 2081–2100 by 0.2 to 0.3 K. Furthermore, the decrease in solar UV radiation leads to a significant delay of stratospheric ozone recovery by 10 years and longer. Therefore, the effects of a solar activity minimum, should it occur, may interfere with international efforts for the protection of global climate and the ozone layer.

Clean Air the Natural Way: A Case for Harmonizing Global Auto Emissions Standards

Across the world, governments are grappling with the effects of global warming. Rising temperatures, increases in the number of natural disasters, and elevated sea levels are just some of the risks posed by Earth's weakening ozone. And yet solutions exist. This article discusses the contribution of auto emissions to global warming and proposes ways for manufacturers to adopt a single emissions standard across their fleets all over the world. As discussed, adopting a single standard based on the most stringent one available poses advantages for manufacturers and also promises to reduce the threat of global warming.

Socially responsible science

The first Mexican-born scientist to become a Nobel laureate in chemistry, Mario Molina shared the 1995 prize for his role in discovering the threat posed by chlorofluorocarbons (CFCs) to Earth's ozone layer. An optimist who passionately pursued science from a young age, Molina now focuses on finding practical solutions to environmental challenges.

The scientific legacy of Sydney Chapman

Sydney Chapman (1888–1970) was arguably one of the greatest scientists of the twentieth century. His comprehensive work on the kinetic theory of gases and solar‐terrestrial physics, as well as on the mechanisms behind the formation of Earth's ozone layer, has inspired a wide swath of research spanning several generations [Van Allen, 1970]. Chapman, a member of the Royal Society, in London, and president of the International Geophysical Year (IGY), also was a recipient of AGU's William Bowie Medal. Young AGU members today may recognize Chapman from the topical conferences that carry his name. Although his biography has so far not been published, he gave three talks on his life: two at the National Center for Atmospheric Research, Boulder, Colo., in 1965 and 1966, and one at the Geophysical Institute, University of Alaska Fairbanks, in 1967 (see Figure 1). All three are transcribed and included in a book, Sydney Chapman, Eighty: From His Friends [Akasofu et al., 1968]. These talks, combined with other sources, shed light on this insightful and discerning scientist.

Attribution of ozone changes to dynamical and chemical processes in CCMs and CTMs

Abstract. Chemistry-climate models (CCMs) are commonly used to simulate the past and future development of Earth's ozone layer. The fully coupled chemistry schemes calculate the chemical production and destruction of ozone interactively and ozone is transported by the simulated atmospheric flow. Due to the complexity of the processes acting on ozone it is not straightforward to disentangle the influence of individual processes on the temporal development of ozone concentrations. A method is introduced here that quantifies the influence of chemistry and transport on ozone concentration changes and that is easily implemented in CCMs and chemistry-transport models (CTMs). In this method, ozone tendencies (i.e. the time rate of change of ozone) are partitioned into a contribution from ozone production and destruction (chemistry) and a contribution from transport of ozone (dynamics). The influence of transport on ozone in a specific region is further divided into export of ozone out of that region and import of ozone from elsewhere into that region. For this purpose, a diagnostic is used that disaggregates the ozone mixing ratio field into 9 separate fields according to in which of 9 predefined regions of the atmosphere the ozone originated. With this diagnostic the ozone mass fluxes between these regions are obtained. Furthermore, this method is used here to attribute long-term changes in ozone to chemistry and transport. The relative change in ozone from one period to another that is due to changes in production or destruction rates, or due to changes in import or export of ozone, are quantified. As such, the diagnostics introduced here can be used to attribute changes in ozone on monthly, interannual and long-term time-scales to the responsible mechanisms. Results from a CCM simulation are shown here as examples, with the main focus of the paper being on introducing the method.

Gamma-ray bursts as a threat to life on Earth

AbstractGamma-ray bursts (GRBs) are likely to have made a number of significant impacts on the Earth during the last billion years. The gamma radiation from a burst within a few kiloparsecs would quickly deplete much of the Earth's protective ozone layer, allowing an increase in solar ultraviolet radiation reaching the surface. This radiation is harmful to life, damaging DNA and causing sunburn. In addition, NO2 produced in the atmosphere would cause a decrease in visible sunlight reaching the surface and could cause global cooling. Nitric acid rain could stress portions of the biosphere, but the increased nitrate deposition could be helpful to land plants. We have used a two-dimensional atmospheric model to investigate the effects on the Earth's atmosphere of GRBs delivering a range of fluences, at various latitudes, at the equinoxes and solstices, and at different times of day. We have estimated DNA damage levels caused by increased solar UVB radiation, reduction in solar visible light due to NO2 opacity, and deposition of nitrates through rainout of HNO3. In this paper we give a concise review of this work and discuss current and future work on extending and improving our estimates of the terrestrial impact of a GRB.

Atmospheric chemistry of HFE-7000 (CF3CF2CF2OCH3) and 2,2,3,3,4,4,4-heptafluoro-1-butanol (CF3CF2CF2CH2OH): kinetic rate coefficients and temperature dependence of reactions with chlorine atoms

The adverse environmental impacts of chlorinated hydrocarbons on the Earth's ozone layer have focused attention on the effort to replace these compounds by nonchlorinated substitutes with environmental acceptability. Hydrofluoroethers (HFEs) and fluorinated alcohols are currently being introduced in many applications for this purpose. Nevertheless, the presence of a great number of C-F bonds drives to atmospheric long-lived compounds with infrared absorption features. Thus, it is necessary to improve our knowledge about lifetimes and global warming potentials (GWP) for these compounds in order to get a complete evaluation of their environmental impact. Tropospheric degradation is expected to be initiated mainly by OH reactions in the gas phase. Nevertheless, Cl atoms reaction may also be important since rate constants are generally larger than those of OH. In the present work, we report the results obtained in the study of the reactions of Cl radicals with HFE-7000 (CF(3)CF(2)CF(2)OCH(3)) (1) and its isomer CF(3)CF(2)CF(2)CH(2)OH (2). Kinetic rate coefficients with Cl atoms have been measured using the discharge flow tube-mass spectrometric technique at 1 Torr of total pressure. The reactions of these chlorofluorocarbons (CFCs) substitutes have been studied under pseudo-first-order kinetic conditions in excess of the fluorinated compounds over Cl atoms. The temperature ranges were 266-333 and 298-353 K for reactions of HFE-7000 and CF(3)CF(2)CF(2)CH(2)OH, respectively. The measured room temperature rate constants were k(Cl+CF(3)CF(2)CF(2)OCH(3)) = (1.24 +/- 0.28) x 10(-13) cm(3) molecule(-1) s(-1)and k(Cl+CF(3)CF(2)CF(2)CH(2)OH) = (8.35 +/- 1.63) x 10(-13) cm(3) molecule(-1) s(-1) (errors are 2sigma + 10% to cover systematic errors). The Arrhenius expression for reaction 1 was k (1)(266-333 K) = (6.1 +/- 3.8) x 10(-13)exp[-(445 +/- 186)/T] cm(3) molecule(-1) s(-1) and k (2)(298-353 K) = (1.9 +/- 0.7) x 10(-12)exp[-(244 +/- 125)/T] cm(3) molecule(-1) s(-1) (errors are 2sigma). The reactions are reported to proceed through the abstraction of an H atom to form HCl and the corresponding halo-alkyl radical. At 298 K and 1 Torr, yields on HCl of 0.95 +/- 0.38 and 0.97 +/- 0.16 (errors are 2sigma) were obtained for CF(3)CF(2)CF(2)OCH(3) and CF(3)CF(2)CF(2)CH(2)OH, respectively. The obtained kinetic rate constants are related to the previous data in the literature, showing a good agreement taking into account the error limits. Comparing the obtained results at room temperature, k (1) and k (2), HFE-7000 is significantly less reactive than its isomer C(3)F(7)CH(2)OH. A similar behavior has been reported for the reactions of other fluorinated alcohols and their isomeric fluorinated ethers with Cl atoms. Literature data, together with the results reported in this work, show that, for both fluorinated ethers and alcohols, the kinetic rate constant may be considered as not dependent on the number of -CF(2)- in the perfluorinated chain. This result may be useful since it is possible to obtain the required physicochemical properties for a given application by changing the number of -CF(2)- without changes in the atmospheric reactivity. Furthermore, lifetimes estimations for these CFCs substitutes are calculated and discussed. The average estimated Cl lifetimes are 256 and 38 years for HFE-7000 and C(3)H(7)CH(2)OH, respectively. The studied CFCs' substitutes are relatively short-lived and OH reaction constitutes their main reactive sink. The average contribution of Cl reactions to global lifetime is about 2% in both cases. Nevertheless, under local conditions as in the marine boundary layer, tau (Cl) values as low as 2.5 and 0.4 years for HFE-7000 and C(3)H(7)CH(2)OH, respectively, are expected, showing that the contribution of Cl to the atmospheric degradation of these CFCs substitutes under such conditions may constitute a relevant sink. In the case of CF(3)CF(2)CF(2)OCH(3), significant activation energy has been measured, thus the use of kinetic rate coefficient only at room temperature would result in underestimations of lifetimes and GWPs. The results obtained in this work may be helpful within the database used in the modeling studies of coastal areas. The knowledge of the atmospheric behavior and the structure-reactivity relationship discussed in this work may also contribute to the development of new environmentally acceptable chemicals. New volatile materials susceptible of emission to the troposphere should be subject to the study of their reactions with OH and Cl in the range of temperature of the troposphere. The knowledge of the temperature dependence of the kinetic rate constants, as it is now reported for the case of reactions 1 and 2, will allow more accurate lifetimes and related magnitudes like GWPs. Nevertheless, a better knowledge of the vertical Cl tropospheric distribution is still required.

Comparison of OMI ozone and UV irradiance data with ground-based measurements at two French sites

Abstract. Ozone Monitoring Instrument (OMI), launched in July 2004, is dedicated to the monitoring of the Earth's ozone, air quality and climate. OMI is the successor of the Total Ozone Mapping Spectrometer (TOMS) instruments and provides among other atmospheric and radiometric quantities the total column of ozone (TOC), the surface ultraviolet (UV) irradiance at several wavelengths, the erythemal dose rates and the erythemal daily doses. The main objective of this work is to compare OMI data with data from ground-based instruments in order to use OMI products (collection 2) for scientific studies. The Laboratoire d'Optique Atmosphérique (LOA) located in Villeneuve d'Ascq (VdA) in the north of France performs solar UV measurements using a spectroradiometer. The site of Briançon in the French Southern Alps is also equipped with a spectroradiometer operated by Interaction Rayonnement Solaire Atmosphère (IRSA). The OMI total ozone column data is obtained from the OMI-TOMS and OMI-DOAS algorithms. The comparison between the TOC retrieved with ground-based measurements and OMI-TOMS data shows good agreement at both sites for all sky conditions with a relative difference for most of points better than 5%. For OMI-DOAS data, the agreement is generally better than 7% and these data show a significant dependence on solar zenith angle. Comparisons of spectral UV on clear sky conditions are also satisfying with relative differences smaller than 10% except at solar zenith angles larger than 65°. On the contrary, results of comparisons of the erythemal dose rates and erythemal daily doses for clear sky show that OMI overestimates surface UV doses at VdA by about 15% and that on cloudy skies, the bias increases. At Briançon, such a bias is observed if data corresponding to snow-covered surface are excluded.

Pioneering remote sensing in the USSR. 2. Global spherical models of radiation transfer

This paper presents a brief overview of the first investigations of the Earth's radiation field, aerosol and ozone layers and the transfer function of the atmosphere from manned space satellites (Soviet Sputniks) concerning remote sensing problems of the Earth's surface. Mathematical tools were created for these investigations and multidimensional spherical and plane models of radiation transfer in the Earth–Atmosphere system were elaborated. These investigations were conducted under Professor K. Ya. Kondratyev's leadership and with his direct participation. The perspectives of a global spherical model of radiation transfer in optical remote sensing data analysis are outlined. Original universal techniques are proposed for the first time for radiation transfer modelling in the Earth–Atmosphere system. The approach is based on the construction of generalized solutions in the form of functionals, the kernels of which are given by the influence functions of the atmosphere. These influence functions with different aerosol and molecular characteristics of scattering and absorption, as well as the different radiation regimes, can thus be calculated by different techniques in various approaches to radiation transfer theory.

Greenhouse gases and future long‐term changes in the stratospheric temperature and the ozone layer

A numerical two‐dimensional (2D) interactive dynamical–radiative–photochemical model including aerosol physics is used to examine the expected long‐term changes in stratospheric temperature and the Earth's ozone layer due to anthropogenic pollution of the atmosphere by the greenhouse gases CO2, CH4 and N2O. The model time‐dependent runs were made for the period from 1975 to 2050. The results of the calculations show that the basic mechanism by which greenhouse gases influence the ozone layer is stratospheric cooling accompanied by a weakness in the efficiency of the catalytic cycles of ozone destruction due to temperature dependencies of the photochemical gas‐phase reactions. Modification of polar stratospheric clouds (PSCs) caused by anthropogenic growth of the greenhouse gases is important only for the polar ozone. An essential influence of the greenhouse gases on the ozone by a modification of the stratospheric sulphate aerosol is revealed. The aerosol changes caused by the greenhouse gases modify the distribution of the ozone‐active gaseous chlorine, bromine and nitrogen components by means of heterogeneous reactions on the aerosol surface, resulting in a significant decrease in springtime polar ozone depletion of the Antarctic ozone hole.

Attribution of recovery in lower‐stratospheric ozone

Multiple satellite and ground‐based observations provide consistent evidence that the thickness of Earth's protective ozone layer has stopped declining since 1997, close to the time of peak stratospheric halogen loading. Regression analyses with Effective Equivalent Stratospheric Chlorine (EESC) in conjunction with further analyses using more sophisticated photochemical model calculations constrained by satellite data demonstrate that the cessation of ozone depletion between 18 and 25 km altitude is consistent with a leveling off of stratospheric abundances of chlorine and bromine, due to the Montreal Protocol and its amendments. However, ozone increases in the lowest part of the stratosphere, from the tropopause to 18 km, account for about half of the improvement in total column ozone during the past 9 years at Northern Hemisphere midlatitudes. The increase in ozone for altitudes below 18 km is most likely driven by changes in transport, rather than driven by declining chlorine and bromine. Even with this evidence that the Montreal Protocol and its amendments are having the desired, positive effect on ozone above 18 km, total column ozone is recovering faster than expected because of the apparent transport driven changes at lower altitudes. Accurate prediction of future levels of stratospheric ozone will require comprehensive understanding of the factors that drive temporal changes at various altitudes and partitioning of the recent transport‐driven increases between natural variability and changes in atmospheric structure perhaps related to anthropogenic climate change.

Environmental Technologies and International Trade

Environmental Technologies and International Trade Haroldo Mattos de Lemos (bio) Introduction Technology is critical to national development. And because the possibility of sustainable development is closely linked to the diffusion of environmental technologies to less developed countries, the market for such technologies is becoming increasingly relevant in the global economy. The purpose of this article is to explore, from the perspective of an environmental engineer, the relationships among economic development, environmental technologies and technology transfer by 1. outlining technology transfer's relationship to the development process; 2. defining and categorizing the technologies related to environ-mental protection; and 3. describing how international trade agreements expand and standardize environmental protection on a global basis. [End Page 56] The article's intended audience is scholars and practitioners interested in the role of environmental technologies in international trade. Hopefully, its insights will help create a context receptive to technological innovations indispensable for those countries seeking to reach new levels of development, and to international trade agreements designed to protect the environment. Technology and Its Importance in the Development Process technology and development Technology is information, knowledge, practical experience, and the ability to use equipment and processes in the production of needed goods and services (Working Group on Environmental Technology Transfer, 1991). Sustainable development has become a contemporary mantra because it supports multiple objectives, including economic growth and environmental protection, all of them desirable. Yet the possibility of achieving such a goal is closely linked to the diffusion of environmental technologies to less developed countries. The capacity to use, modify, retain, and constantly improve information and knowledge so as to produce goods and services more effectively depends on factors that are both explicit (e.g., factories, equipment, and infrastructure) and implicit (e.g., education, experience, training handbooks, organization structures, or management capacity; Wallender, 1979). Technology is in people's brains as well as in their machines. Technology is the most important factor in the development process. Whatever competitive advantages a country may have are less and less dependent on the availability of raw materials or cheap labor, and more and more on its ability to use new technologies and apply them to other productive processes (United Nations Centre for Trade and Development, 1990). Because new technologies are capital and knowledge intensive, it is easier for high-technology companies to raise funds and establish themselves in any country, with little regard to the availability of raw material or specialized labor in that region. The strategic importance of technology for national economic development guarantees that diffusion and adoption will occur by a range of methods, including legal purchase and licensing agreements, or illegal transfers (e.g., theft, forgery, copying, and smuggling) that do not respect intellectual property rights. Although these legal [End Page 57] and illegal methods apply to technology transfer in general, environmental technologies illustrate some unintended consequences of technology transfer in this area. the environmental impact of technologies: unanticipated consequences Technological choices determine the kind of impacts imposed over the environment and natural resources (United Nations Environment Programme [UNEP], 1988). Technologies may have great impacts—positive or negative—on a short-, medium-, or long-term basis. For example, refrigeration technology improved dramatically with the discovery of chlorofluo-rocarbons (CFCs) around 1930. Until then, the gas used for refrigeration was ammonia, which caused serious problems because of its strong smell, toxicity, and flammability. On the other hand, CFCs were odorless, colorless, nonpoisonous, nonflammable, and extremely stable in the lower atmosphere. Owing to these qualities, they were used not only in refrigerators, but also as propellants in perfumes and aerosol sprays. It was only after these compounds had been released into the atmosphere for over 40 years that we discovered their negative environmental impact—when subjected to ultraviolet radiation, they release chlorine atoms that destroy the earth's ozone layer, increasing the amount of ultraviolet radiation reaching the earth and causing a dramatic increase in skin cancers. Thus, our greatest continuing challenge is learning to use technology in ways that improve productivity without generating significant environmental problems or damaging the availability of strategic natural resources. issues in technology transfer and development Beyond the unexpected outcomes that can come from technology, even the movement and transfer of...

Ambient Levels of Ultraviolet-B Radiation Cause Mortality in Juvenile Western Toads, Bufo boreas

Numerous anthropogenic and natural factors affect living organisms in nature. Anthropogenic factors include a wide array of contaminants and processes that alter the habitat on both local and global scales. For example, chlorofluorocarbons (CFCs) and other industrial gases contribute to the depletion of the earth's protective ozone layer, resulting in increased amounts of cell damaging ultraviolet-B (UV-B) radiation reaching the surface of the earth. Recent experiments provide evidence that increasing ambient levels of UV-B radiation harm many amphibian species. UV-B radiation can kill amphibians and can cause sublethal damage to them. However, most studies that have examined the effects of UV-B radiation on amphibians have focused on developing embryos. There is little information on how UV-B radiation affects amphibians at later stages of development. In experimental laboratory tests, we exposed one group of juvenile western toads (Bufo boreas) to full spectrum lighting with ambient levels of UV-B radiation and control toads to full spectrum lighting excluding most UV-B. Juvenile toads exposed to ambient levels of UV-B radiation showed significantly greater mortality rates compared with controls. These results add to a growing body of literature demonstrating that UV-B is harmful to amphibians. Furthermore, our results suggest that investigators should look at the effects of UV-B radiation on different life stages before making conclusions about the overall impact of UV-B on amphibians.

A condition and dynamics of the earth's ozone layer with attention on the Montreal protocol

The paper presents the analyses of the condition and dynamics of earth's ozone layer on the base of the latest satellite measurements and estimated results of the pollutants emissions. On the basis of those results it presented an attempt of explanation of the ozone layer dynamics by prospective causality. Furthermore, paper work contents analyses of activities and measures that are provided by international document known as Montreal Protocol on Substances that Deplete the Ozone Layer.

The treaty that worked

The treaty that worked

The Economic Analysis of Growing Greenhouse Cucumber with Soilless Culture System: The Case of Turkey

ABSTRACT Methyl bromide contributes to the destruction of the Earth's protective ozone layer in the atmosphere, so it makes sense to move production of some high value crops out of the soil altogether. The use of hydroponic technology or soilless culture can be a viable alternative to methyl bromide soil fumigation for greenhouse vegetable production. In Turkey, vegetable production in greenhouses is generally conventional. Soilless vegetable production in greenhouses is a new approach in sustainable agriculture in Turkey. For example, soilless production of cucumbers can provide an alternative, but little is known about the economics of this type of enterprise. Therefore, there is a need to do an economic study and cost and return analysis at local level and under grower conditions. This study aims at evaluating the economic feasibility of growing greenhouse cucumber with soilless culture system. According to results of this study, net return obtained from greenhouse cucumbers was determined to be $1.81/m2 and $0.07/kg.

Climate change, ozone depletion and the impact on ultraviolet exposure of human skin

For 30 years there has been concern that anthropogenic damage to the Earth's stratospheric ozone layer will lead to an increase of solar ultraviolet (UV) radiation reaching the Earth's surface, with a consequent adverse impact on human health, especially to the skin. More recently, there has been an increased awareness of the interactions between ozone depletion and climate change (global warming), which could also impact on human exposure to terrestrial UV. The most serious effect of changing UV exposure of human skin is the potential rise in incidence of skin cancers. Risk estimates of this disease associated with ozone depletion suggest that an additional peak incidence of 5000 cases of skin cancer per year in the UK would occur around the mid-part of this century. Climate change, which is predicted to lead to an increased frequency of extreme temperature events and high summer temperatures, will become more frequent in the UK. This could impact on human UV exposure by encouraging people to spend more time in the sun. Whilst future social trends remain uncertain, it is likely that over this century behaviour associated with climate change, rather than ozone depletion, will be the largest determinant of sun exposure, and consequent impact on skin cancer, of the UK population.