According to the standard data, the average annual permissible limit of SPM is 140 micrograms per cubic metre and 200 micrograms per cubic metre for 24 hours. For RPM, the average annual limit is 60 micrograms per cubic metre and 100 micrograms per cubic metre for 24 hours. A WHO report also showed that dust pollution caused about 5,700 premature deaths in Kolkata every year.

Taking these into consideration, the PWD has listed a number of instructions for construction agencies: the project site or under-construction building has to be covered with geotextile fabric, dust barriers have to be installed, water has to be splashed on the structures to prevent dust from rising, soil has to be maintained in a visibly damp or crusted condition for temporary stabilisation, workers will have to water the area before levelling the ground or any other earth-moving activity and dust suppressants have to be applied on building materials.

At the end of the day, the site has to be cleaned up and the debris must be disposed of properly, after consultation with the local civic authorities.

The construction agencies will have to submit a report — confirming their compliance of the guidelines, the preventive measures that have been taken and the faulty practices they have discarded — which will be forwarded to the environment department. Superintendents and executive engineers of PWD have been directed to take necessary action.

The PWD has also ordered to limit vehicle speed near construction sites to 15mph to avoid dust particles to rise in the air, besides keeping the noise level to 65 decibels; so, equipment without proper dust-control or noise-control facility can no longer be used. Also, outsiders should not be allowed on the site to limit soil disturbance.

The guidelines have also banned the burning of tyres in hot mix plant usually meant to melt tar for road repairs.