Coimbatore: Two weeks after the citizen driven air pollution monitoring exercise was launched in Coimbatore, the readings taken at Hopes College where a sensor was installed has shown that pollution levels at this spot was higher than permissible levels.

The quantum of respiratory suspended particulate matter (RSPM) has touched a high of 200 microgram/m3 to 600 microgram/m3 during the peak hours of 6.30pm to 9pm at Hopes College signal. This is very high compared to the permissible pollution levels prescribed by World Health Organization which stand at just 12 microgram/m3 of particulate matter. These particles in the air are made up of a mixture of soot, organic and inorganic materials which when inhaled cause serious health problems.

Though pollution levels during the peak hours in the morning were mostly well within the permissible levels and hovered around an average of 10 microgram/m3, readings show that pollution levels, sometimes touched 200 microgram/m3 during the mornings. "However, we can't say the the pollution levels are alarming as the highest amount of RSPM recorded by the pollution monitor we had installed was not constant even during peak hours. The pollution level touched the peak only very few times during the two weeks we monitored,'' said Antony Deepak, member of a city-based organization of social entrepreneurs named SPICE foundation, which launched the initiative called Citysenze.

The pollution monitor was developed by Antony Deepak using a low cost infra red filter which can count of particles that can go through the sensor.

The level of RSPM is however higher than the pollution data recorded by TNPCB for the whole city because the board calculates only average pollution level of the whole city during a particular period and not location specific. "The average is around 10 mg/m3 which is lower than the WHO prescribed levels," said Deepak.

However, data declared by TNPCB has also shown that air pollution levels have been continuously going up. The city recorded a RSPM of 43 in 2003-'04, rose to 53 the following year and went as high as 68 in 2011-12. Pollution levels went down only once in 2005-'06 to 39 and 44 in 2006-'07.

Pollution control experts say there could be a specific reason for the difference in data but they also agree that pollution levels in Coimbatore are comparatively good. "Hopes Signal area is populated with trees which are very good absorbers of particulate matter," said senior scientist at IFGTB, Rekha R Warrier. " So, if the meter was slightly interior rather than on a median on Avinashi Road, the readings might be lower," she said.