Question raised in Lok Sabha on Pollution in Two-Tier Cities, 26/04/2016. The Central Pollution Control Board (CPCB) is monitoring ambient air quality in 74 Tier-II cities. The ambient air quality data for the period 2015 pertaining to two-tier cities in the country given at Annexure. Analysis of data shows that 41 cities exceed the ambient air quality standard. In addition these cities are also facing problem of water pollution due to discharges of untreated sewage.