In civil engineering this condition is known as efflorescence this condition occurs due to capillary action of water in brick in which water contains diffrent salts comes on surface through voids of brick and evaporates and salt rest on surface as shown in image this salts may be harmful or not this depends on type and chemistry of salts generally it is not harmful

ok pls provide me more details

Hello there, I would recommend AAC blocks as they are very fast to build and are economical as well. Regards, Aurum Ideas and Spaces Bhubaneswar

AHC , Exposed bricks look definitely add charm to the walls. There are many ways of attaining the same look. Below appears to be a wall paper - it is the easiest way to achieve the look however we do not recommend it . There are brick tiles available and you can get the mounted on the walls for a great quality wall look. Thanks Nitin Cornerstone Designs, Bangalore