New studies confirm previous investigations

Mar 17, 2010 13:59 GMT  ·  By
UV-B radiation can easily harm human DNA and increase the incidence of various diseases
   UV-B radiation can easily harm human DNA and increase the incidence of various diseases

Experts looking at more than three decades-worth of data have recently concluded that the levels of ultraviolet radiations we were exposed to over the past 30 years had been increasing steadily. However, it would now appear that the trend is starting to level off, largely due to the introduction of the Montreal agreement, which saw the use of chlorofluorocarbons (CFC) – the main source of ozone-destructing gases – being severely cut down. The investigators, who looked at long-term satellite data, say that the leveling off seen in the radiation exposure trend is owed directly to these measures.

According to NASA scientists, the highest increases were recorded in mid-and-high latitudes, whereas almost no change was recorded at the Equator and in tropical regions. Areas located along the 32.5-degree latitude line had it worst off, experiencing a 6 percent increase in the 305-nanometer ultraviolet (UV) radiation level each year. This particular line passes through the American state of Texas in the Northern Hemisphere, and through the country of Uruguay in the Southern Hemisphere. Chemists say that the primary reason why these levels surged was the excessive use of CFC by the industry, in everything from refrigerators to hair sprays.

“Overall, we're still not where we'd like to be with ozone, but we're on the right track. We do still see an increase in UV on a 30-year timescale, but it's moderate, it could have been worse, and it appears to have leveled off,” explains NASA Goddard Space Flight Center (GSFC) scientist and study team member Jay Herman. The group introduced massive amounts of data in their analysis, including information obtained from the NASA Aura satellites, the NOAA weather satellite constellation, and commercial satellites as well. The data validates other works, which showed that the 1987 Montreal agreement actually had a direct effect on the ozone layer.

This colorless gas acts in very much the same way a sunshield does, protecting our planet from the damaging effects of UV radiation. Longer wavelengths (from 320 to 400 nanometers) of ultraviolet-range photons (UV-A) cause sunburn and cataracts, whereas UV-B (320 to 290 nanometers) tend to damage DNA by tangling and distorting its ladder-like structure. In fact, it is believed that life may have not developed on our planet had it not been for this protective layer.