Levels of respirable suspended particulate matter (RSPM10) and particulate matter 2.5, which are mainly on account of dust going in air during construction work are almost three times more at few places than the national ambient air quality standards of Central Pollution Control Board (CPCB).

Contrary to general impression that vehicles are the real culprit, there is a drop in pollution over the years. Surprising as 125 new vehicles hit the roads every day in a city, where the number has touched 12 lakh.

Air pollution is measured by taking into account level of sulphur dioxide (SO2), nitrogen oxides (Nox), RSPM10 and fine particulate matter (PM2.5) in the air.

Cause of SO2 is vehicles. Nox is due to human activity, including vehicles and sewage among others.

RSPM 10 is due to dust, construction, including building of roads and PM2.5 is due to dust, human activity and climatic conditions.

Of the four, officials said, PM2.5 is most harmful to health since it goes inside human body and causes severe lung diseases.

Sampling locations for air pollution in Bhopal are Hamidia Road, Govindpura, ParyavaranParisar and Kolar. Hamidia Road is most polluted.

In all these places, SO2 and Nox have registered a decline while and RSPM 10 has increased over the years. Officials said value of PM 2.5 is being taken in account in Bhopal since 2015 as a result of which there is no comparative data available for years.

As per the national ambient air quality standards, there are seven pollutants measured to find out ambient air quality. They are SO2, Nox, RSPM 10, PM 2.5, ozone, lead, carbon and ammonia. As of now, only SO2, Nox, RSPM 10, PM 2.5 are measured in Madhya Pradesh.

Officials said they are in process to start measuring remaining four pollutants and it will be started in near future.

As for why vehicular pollution is going down, officials said fuel quantity has been improved over the years. The quantity of lead that would cause pollution has come down in fuel.

Secondly, number of new vehicles is increasing, but not old vehicles that cause heavy pollution. Good quality of roads led to better driving conditions, which helped reduce pollution, officials said.

MPPCB chief chemist Shyamanuj Tiwari said overall the air pollution in Bhopal is not alarmingly high. Green cover and plantation in the city help keep pollution level in check. Central verge on roads, in particular, with herbs of height up to 5 feet helps absorb the pollution. Level of pollution will be less if there is a proper dispersal. Pollution level goes up in places like Hamidia Road since dispersion on road is not proper there due to which air pollution gets concentrated at one place, he said.

Why pollution is not measured in several areas of Bhopal like densely populated Hoshangabad Road, officials said areas are classified under commercial, residential and industrial heads on the basis of activities. For instance, BaghSewania is a residential area. Type of activities there will be same like in Arera Colony, the residential area where air quality is monitored on a regular basis.