packed in polyethylene sheeting or acid-free corrugated cardboard, may be used to individually wrap pieces to prevent accidental contamination of objects between handling and display. Solid pollutants Particulate contaminants, including pollen, dust, fibers, and soot, may affix to objects after entering collection areas through poorly maintained ventilation systems. Individuals passing through a collection area may also have particulates embedded on their clothing or bodies, which can become dislodged thereby becoming an airborne contaminant. Construction or maintenance efforts are another common cause of particulate pollution. Particulates which adhere to collection objects may cause soiling or blemishing, requiring mechanical removal and conservation efforts. These pollutants can be minimized via high quality HVAC systems, regularly replaced filters for vents, and careful placement of objects away from high-risk areas such as designated smoking sections, construction sites, and high-traffic areas such as entryways. Dust can contain a number of materials including skin, mold and inorganic fragments like silica or sulfur. It is important to keep collections free of dust whenever possible because it can become bound to a surface over time, making it significantly more difficult to remove. Dust is hygroscopic, meaning it is able to attract and hold water molecules creating an ideal climate for mold spores to grow and cause biological damage. Dust's hygroscopic nature can also prompt chemical reactions on a surface, especially upon metals. Inorganic dust particles may have tough sharp edges which can tear fibers and abrade softer surfaces if not properly removed. The best way to prevent damage from dust is to control and prevent substantial buildup of dust in the first place. This can be done by using air filters in heating and air conditioning systems as well as using vacuum cleaners equipped with HEPA filters when possible. Care should be taken when wiping a clean cloth over a surface dusty with these inorganic particles because it may result in irreversible abrasions and vacuums should be used if soft surfaces are being cleaned. Limiting the amount of exposed surface areas of collections can also prevent dust from settling on objects. This can be done by storing objects in acid-free boxes, object specific enclosures, in drawers or covering open shelves with a polyethylene sheet. Pests Damage from insects and other museum pests typically occurs because these pests are drawn to collections objects which they view as a food source. Certain material types, such as wood, organic textiles, furs, and