Tehran Times - Temperature dropped by 1.1 degrees Celsius in Tehran over the Iranian calendar month of Mordad (July 22- August 23) compared to a month earlier, so that ozone pollution is dissipating dramatically, Hossein Shahidzadeh, the caretaker for Air Quality Control Company has said.

Ozone in the lower atmosphere is formed by the reaction of sunlight on air containing hydrocarbons and nitrogen oxides (NOX) that react to form ozone directly at the source of the pollution namely, cars, industry, gas vapors, chemical solvents, fuel combustion.

Ozone is best known as the layer of gas in the earth�s atmosphere that protects humans from harmful ultraviolet rays, exposure to which can cause cancer and other health issues.

Ground-level ozone polluted the capital�s air for 13 days during the first month of summer (June 22-July 21), while over the second month of summer the concentration of the pollutant decreased relatively, leaving the capital�s air quality polluted for sensitive groups for 4 days.

Too much ozone at the ground level can damage cells in the lungs and other organs.

Ground-level ozone polluted the capital�s air for 13 days during the first month of summer (June 22-July 21), while over the second month of summer the concentration of the pollutant decreased relatively, leaving the capital�s air quality polluted for sensitive groups for 4 days.

The highest concentration of ozone at ground level occurs in the afternoon and during the hot seasons, Shahidzadeh said, adding, this year, temperature increased over the month of Khordad (May 22-June 21) and led to the accumulation of ozone which haunted Tehran for 25 days.

He stated that the concentration of ozone is directly related to the increase and decrease of temperature and intensity of radiation, adding, this year and last year, ozone hit the capital in July more than August.

Last year, Tehraners experienced 12 days of polluted air quality contaminated by ozone during the first two months of summer, which has been compounded this year reaching 15 days, he explained.

During the first month of summer, Tehran�s temperature reported 32.6 �C, however, it decreased by 1.1�C a month later, he said, ISNA reported on Monday.

He went on to add that the average daily radiation was 292.5 during month of Tir (June 22-July 22) which decreased to 258.4 in Mordad (July 23-August 22); therefore, the invisible pollutant blanketing the capital decreased.

In fact, polluted summer phenomenon has haunted the metropolis of Tehran since 3 years ago which has been compounded this year.

Shahidzadeh told Khabaronline in June that curbing ozone emission can come up with several solutions, one of which is the implementation of a scheme for vapor recovery through which a system was installed to separate organic vapors from air and off-gases in the stations, however, the scheme is developing at a low pace.

Another way to improve the situation is scrappage of clunker cars, which means discarding the old cars and motorcycles, as over 60 percent of motorcycles amounting to 1.5 million are extremely old which must be scrapped, he noted.