New Delhi - Pollution hit "hazardous" levels in New Delhi as Angelo Mathews and skipper Dinesh Chandimal steered Sri Lanka to 192-3 at lunch on day three of the third Test on Monday.
A day after Sri Lanka's fielders donned facemasks and protested over the air pollution, which made some of them vomit, Mathews, on 90, and Chandimal, on 52, stood firm.
The pair put on an unbeaten 117-run stand after the visitors resumed on their overnight 131-3 at a smog-shrouded Feroz Shah Kotla ground.
The visitors trail by 344 runs after India declared their first innings on 536-7 Sunday, when play was briefly halted because of the bad air.
While official indicators showed pollution levels rising to "hazardous" levels, there was no repeat of protests by the visitors that halted play for about 20 minutes on Sunday.
However Chandimal did require help from a trainer early in the day as it seemed the batsman felt unwell. He took a break and sipped water before resuming batting.
The batsmen maintained a strong defence, forcing Indian skipper Virat Kohli to juggle his bowling options on a batting-friendly wicket.
Mathews, who struck form with a gritty half-century Sunday, hit regular boundaries taking his tally to 11 fours and two sixes.
Chandimal brought up a patient third fifty in successive innings to ensure that Sri Lanka do not lose a wicket in the session.
Sri Lanka, who trail the three-match series 1-0 after their thrashing in the second game, need a win to draw the series against top-ranked India.