The SC on Friday sought response from the Centre and the Railways on the allegation that the use of sub-standard materials for furnishing interiors of coaches was causing asphyxiation deaths due to inhalation of toxic gases by passengers during fire accidents in trains. The apex court also issued notices to the departments concerned of the Railways --Railway Designs and Standards Organisation, Rail India Technical and Economic Services Ltd, rail coach factories at Kapurthala in Punjab and Lalganj in Rae Bareli, and Integral Coach Factory, Chennai. They were asked to respond to the allegation that the supply of sub-standard materials for train coaches was due to a nexus between a cartel of vendors and officials.