NEW DELHI (Reuters) - India suspended most construction and demolition activities in and around Delhi on Friday after its air quality deteriorated and was forecast to worsen because of calmer winds and other atmospheric conditions, a government body said.

The national capital region's air gets filthy every winter as low temperatures and wind speeds trap emissions from vehicles, burning of farm wastes, and industries. Many of Delhi's 20 million residents complain of serious breathing problems between November and January.

The Commission for Air Quality Management in the National Capital Region and Adjoining Areas said Delhi's air quality hit 399 on Friday - in the "very poor" category - and was forecast to become "severe" in the coming days because of "calm wind and stable atmospheric conditions".

A reading of up to 50 is considered "good", and such days are rare in Delhi's winter.

The commission immediately banned construction and demolition activities except for certain projects, such as those related to hospitals and healthcare, or national security and defence. The commission also directed a closure of all brick kilns and industries using dirty fuels.

(Reporting by Sakshi Dayal; Editing by Krishna N. Das)