The levels of harmful solar ultraviolet (UV) radiation over Mumbai have increased owing to truant monsoon this year, data from the Indian Institute of Tropical Meteorology (IITM), Pune, has revealed.
Over the past four months, sporadic rainfall saw Mumbai’s UV Index (UVI) levels touch the ‘high risk’ category. Their immediate effect can be seen in form of sun burns, long-term exposure can lead to skin cancer and cataract.
“The sporadic rain pattern is responsible for the high UV radiations in the city this monsoon,” said Gufran Beig, project director, System of Air Quality and Weather Forecasting and Research (SAFAR), IITM. “When (the number of) rainy days are less followed by a long period of sunny days, UV radiation levels peak.”
The high risk category – between 7 to 10 UVI – means everyone is at risk. It is therefore advisable to avoid direct sun exposure. The maximum risk of UV radiations is between noon and 3pm with its peak at 1pm. For instance, UVI touched 10 on three days in June and one day in August, while UVI breached the 9 mark for most days in August.
This is the first year that UVI is being recorded for Mumbai under the SAFAR project. But a look at UVI recorded at Pune for the last four months shows a sharp contrast to that of last year. Good rains last year saw Pune’s UVI in the low to medium category (UVI below 5), while deficient rain this year has pushed UVI above 7, which is the medium to high risk category.
“Continuous rain ensures that pollutants close to the earth’s surface get washed away and the atmosphere is cleared off them. So when the UV rays enter the earth’s atmosphere, they do not reflect back into the lower levels of the atmosphere as the rays don’t get scattered by the pollutants,” said Beig.