According to the study, Patrapada has emerged as the most polluted area in Bhubaneswar. The rise in air pollution has been attributed to drop in temperature and foggy conditions in the city.

The level of air pollution is proportional to the quantity of particulate matter present in the atmosphere. Particulate matter is the sum of all solid and liquid particles suspended in air. It includes both organic and inorganic particles such as dust, pollen, soot, smoke and liquid droplets.

Fine particulate matter is 2.5 microns in diameter and less. It is also known to penetrate the respiratory system further than larger particles. The matter reduces visibility and causes the air to appear hazy when its levels are elevated. Besides, the pollution level is also measured in particulate matter 10 - which is 10 micro metres or less in diameter.

Air pollution quality is gauged using two methods - respirable suspended particulate matter and fine particulate matter. The standard size of fine particulate matter should be 2.5 microns or less in the air. If its quantity is recorded over 60 micrograms in one-metre area, the air is considered to be polluted or unsafe for breathing. However, the standard size of respirable suspended particulate matter is little larger than fine particulate matter. If its quantity crosses 100 micrograms, the air pollution is considered to be on the rise.

The normal fine particulate matter is below 60 micrograms. The board's study reveals that the fine particulate matter was 73 micrograms at Capital police station, 95 micrograms at IRC Village, 121 micrograms at Patrapada, 47 micrograms in Central Laboratory and 47 micrograms at Palasuni Square.

Similarly, the normal particulate matter is below 100 micrograms. While it was 115 micrograms at Capital police station, 114 micrograms at IRC village, 210 micrograms at Patrapada, 78 micrograms at Central Laboratory and 120 micrograms at Palasuni Square.

Last October, the fine particulate matter was 60 micrograms at Capital police station, 85 micrograms at IRC village, 100 micrograms at Patrapada, 40 micrograms in Central Laboratory and 43 micrograms at Palasuni Square. Similarly, the particulate matter was 105 micrograms at Capital police station, 107 micrograms at IRC village, 185 micrograms at Patrapada, 65 micrograms in Central Laboratory and 110 micrograms at Palasuni Square.

Environmentalists feel that although the situation may not be alarming yet, but it can worsen if remedial steps are not taken on time.

"Following drop in temperature and foggy conditions, a marked increase in the air pollution level has been recorded in Bhubaneswar," said the board's regional officer HadibandhuPanigrahi.

He said vehicular pollution consisted of more than 40 per cent of pollutants. The city's public transport system is dependent on diesel.

"As Bhubaneswar is growing as a city, the need of the hour is to introduce environment friendly compressed natural gas in the public transport vehicles," said environment scientist A.N. Hota. He said the strategy was adopted in Delhi and showed positive results.

Hota said the transport department must intensify its drive to ensure vehicles plying in the city had the mandatory pollution control certificate. Besides, increase in construction activities in the city has worsened the situation. Panigrahi said despite the board's orders, sprinkling of water at construction sites was a rarity. He said dust rising from those sites during winter had contributed significantly to the rise in air pollution, and intense fog till late in the morning triggered respiratory problems among residents. He warned that the situation might deteriorate in future if precautionary measures were not taken.

The board has installed air pollution monitoring devices at various locations in the city, including Capital police station, IRC Village, Patrapada, Central Laboratory and Palasuni Square, besides its office at Nayapalli.