Concrete Caution:
Concrete, that ubiquitous building material, is a combination of several materials. Basic concrete contains sand, gravel, water, and portland cement. The cement and water react to form the rocklike material we call concrete. Many home projects incorporate concrete or other portland cement products, such as mortar or stucco. While most people recognize the difficulty of working with concrete because of its heavy weight, there is another hazard often overlooked. Portland cement is very caustic. Skin contact should be avoided. Wear long pants and long sleeves when working with concrete. When mixing dry ingredients, wear respiratory protection to avoid breathing the dust. Wear safety glasses or goggles. If skin does come in contact with portland cement or wet concrete, wash it off immediately.
Efflorescence:
Masonry surfaces, typically brick walls, occasionally present us with a white chalky stain. If this is occurring below a painted window or siding, chances are the paint is chalking and washing down. No cause for alarm--it's just unsightly. Another cause might be efflorescence: a type of mineral deposit left behind by water passing through the bricks and evaporating at the surface. Efflorescence may be reason for concern. Wash the affected area to remove the deposits. If they don't return, forget about it. If the deposits return or grow larger, water is moving through the wall and might indicate a bigger problem. Consult a professional if necessary.