Skin Cancer and Cataracts From Your Car – Poor UV Side Protection – Windows Tested From 15 Vehicle Makers. As summer approaches many of us will be spending more time in our cars – oblivious to the fact that this activity may be increasing our risk of skin cancer or cataracts. Recent research showed the side windows of a large number of vehicles (see list below) provided much lower levels of UV resistance than the front windscreens. This may well explain the higher incidence of cancers and cataracts on the sides of drivers closest to vehicle side windows.
During the last year I found myself becoming more interested in the causes of skin cancer. This was partly due to allergy problems I experienced with my own skin last summer (reported here and here). At about the same time my father needed to have an operation for a Basel Cell Carcinoma on his nose. As a result of these events I found myself paying much more attention to that part of the body that most of us take for granted – our skin.
As I approach 60 years of age I am also becoming aware of how my skin changes with age. These changes are especially apparent where the skin is directly exposed to the elements – mainly the sun – like the hands and face. It is interesting to note how those areas that are less exposed to the sun have aged very little (perhaps a skin transplant from my bottom to my face could rejuvenate my youthful looks?). To highlight the impact of sunlight on ageing I have included a photo below from a 2012 article in the New England Journal of Medicine. It is of a man who had been driving trucks for 28 years and illustrates the damage to the side of his face caused by the lower levels of UV protection from his vehicle side window.
Actually if you cover up the damaged part of his face it is interesting to observe how young the rest of the skin of this 68 year old man appears. This no doubt reflects the very high levels of UV protection the rest of his face received from the laminated front windscreen of his vehicle. One of the characteristics of the laminated glass used for vehicle windscreens is that it acts as a very good screen against UV light. Sadly this does not appear to be the case for the side windows on the left side window of his truck – presumably a different kind of glass was used.
This differential exposure to the damage cause by sunlight does not just lead to accelerated skin ageing – it can also lead to an increased incidence of skin cancer and other illnesses like cataracts of the eyes. There have been a number of studies in which a higher incidence of skin cancer and cataracts have been identified on the left side of people driving in countries where drivers sit on the left hand side of their vehicles. Interestingly studies in Australia where drivers sit on the right hand side (as in the UK and South Africa) have documented an increased incidence of sun related skin damage on the opposite side of the face.
The issue of road vehicle side window UV protection was addressed in an article published last week in the on-line scientific journal JAMA Ophthalmology. In this article Brian S. Boxer Wachler, MD, published the results of his investigations into levels of UV protection provided by windows of 29 vehicles from 15 car manufacturers. He used a UV-A measuring device to measure the amount of blockage of UV-A radiation by windshields and side windows of the vehicles tested.
Generally the level of protection provided by the windshield at the front of these vehicles was high with an average blockage of 96% (the range measured was from 95-98%). However the average UV-A blockage from the side windows was much lower at 71% with some vehicles measuring as low as 44%. The table of results from the article for each vehicle is included below (click on the table to enable enlargement of the text).
From the results of the research it is interesting to note that some of the most prestigious brands (2012 Porsche Turbo S, 2013 BMW 320i/328ia) had markedly lower protection from the side windows compared with the front windscreens (40 and 42% lower respectively). Other prestige makes gave much better protection from the side – like the Lexus models: Rx350 (2011), Rx450H (2013) and RX350 (2011) – which gave side window UV protection reductions of only 0 – 4%. Some manufacturers showed year to year variation for example a Mercedes 5550 from 2013 gave 95% UV protection from its side windows whereas a Mercedes E550 from 2009 only provided 44% protection. Both cars provided 96% protection through their front windscreen.
Age of vehicle was not a good indicator of protection with a Buick Riviera from 1990 giving better side protection (65%) than a 2014 Audi A6 or Q5 (63 and 64% respectively). Just based on UV side protection the old Buick would be a better buy than the 2013 Porsche Turbo S (56% side protection).
As all the manufacturers shown in the table above were able to provide consistently good UV protection through their front windscreens the lack of consistent protection from the side was clearly not a technology issue. Presumably other issues like cost were taken into account by those manufacturers of vehicles with low levels of side protection. The lamination process used in the manufacture of windscreens (to make them break more safely upon impact) also helps to improve the level of UV protection provided.
Skin cancer is one of the most common forms of cancer in the world – causing about 40% of cancer globally. At least 90% of skin cancer is due to exposure to UV radiation. Drivers and passengers often presume they do not need to wear sunblock inside their vehicles – an illusion that is made worse by the cool atmosphere provided by the use of air conditioning. Cataracts, which cause blindness, are found in about half the population of the USA by the age of 80. They can also be caused by exposure to UV light. Many parents provide their children with booster seats in their cars which raise the position of their face closer to the side windows. The above research indicates that for certain vehicles the closer your skin is to the side window the greater is the potential harm from UV radiation. Therefore appropriate protective measures should be taken (long sleeved clothing, hats and sun block when sitting inside a car).
Of the types of skin cancer the Basal Cell Carcinoma is the most common and can usually be treated successfully without becoming malignant. The next most common form of skin cancer is the squamous cell carcinoma, this is more likely to become malignant than the Basel Cell type. The least common form but the one most likely to become malignant and cause death is the Malignant Melanoma. The best way to reduce the risk from all these and all other forms of skin cancer is to minimise your exposure to UV radiation from the sun. When you buy your next car it is worth checking out the UV specification for all the windows – in particular look for a significant difference in the UV protection levels between the windscreen (generally high) and the side windows (currently very variable). They should both be similar and provide high UV blockage.
By the way don’t presume that if your car has tinted side windows you are protected from UV radiation. Generally the tints reduce the transparency of the window to light in the visible part of the spectrum – therefore the tint may have limited, if any, impact on the level of harmful UV radiation that can pass through the glass.
If you are interested in reading my other health focused articles try the following