Sept 30 (Reuters) - The Baltic Exchange's main sea freight index, which tracks rates for ships ferrying dry bulk commodities, fell for the fourth straight session on Monday on weaker capesize demand.
* The Baltic index, which reflects rates for capesize, panamax and supramax vessels, fell 34 points, or 1.83%, to 1,823 points, its lowest since Aug. 12.
* The main index posted its largest monthly percentage fall since January.
* The capesize index also fell for the fourth consecutive session, shedding 69 points, or 2.1%, to 3,269 points.
* The index has fallen 27.3% in September, snapping four consecutive months of gains.
* The average daily earnings for capesizes, which typically transport 170,000-180,000 tonne cargoes such as iron ore and coal, dipped by $514 to $24,402
* A large number of China's steel mills have been ordered to shut or limit operations starting last week to curb pollution ahead of a week-long holiday in Beijing, weighing on demand for capesize vessels.
* The panamax index slipped 38 points, or 2.1%, to 1,804 points.
* Average daily earnings for panamaxes, which usually carry coal or grain cargoes of about 60,000 tonnes to 70,000 tonnes, fell by $304 to $14,140.
* The supramax index dropped 12 points to 1,248 points. (Reporting by Nakul Iyer in Bengaluru)