Improper environmental conditions may cause irreparable loss of cultural relics. Important factors include: temperature, relative humidity, light, dust pollution, molecular (gaseous) pollution and harmful substances.
Despite natural sources such as hot springs and volcanoes, most of the molecular pollutants in the air are due to human activities, such as power generation and transportation. Usually associated with high population density, such as cities.
The molecular pollutants that are harmful to cultural relics can be divided into two categories:
Acidic chemical substance
2. Oxidizing chemicals
Acidity causes corrosion damage to materials such as metals and marble. Other sensitive materials include leather, wool, silk, paper, photographic materials, and more.
The main oxidizing gases are ozone, nitric acid and other oxidation and nitrides. These gases mainly cause damage to organic materials, similar to premature aging. Typical visual changes caused by oxidation include metal yellowing, brittleness, fading, and tarnishing.
Molecular contamination is based on the specified concentration of single or multiple chemical substances.
Solutions for molecular contamination
The use of molecular filtration to control harmful pollutants is very economical and cost-effective, thereby ensuring safe storage and display conditions. The use of different solutions depends on the type and concentration of gaseous pollutants, the type of cultural relics to be protected, and the design of the ventilation system.
Molecular filters can be applied to both fresh air supply and return air. In fresh air supply, high external concentrations and one-way operation need to be considered. Consider lower ambient concentrations and multi-pass operation in return air applications.
Dust pollutants come from a variety of sources, such as combustion processes (industrial, power stations, vehicle exhaust, cigarettes), tires of moving vehicles, building activities and human activities. Heavy metal-containing dust is abrasive and can cause scratches on the surface. The small dust remains suspended and is transported to the corners and display cabinets of the room as the air moves, which becomes stains or dirt due to surface deposition.
Many dusts, especially particles produced during the combustion process, are very oily or dark in nature and are acidic. These particles are very sticky and can cause corrosion of many materials, which will cause huge damage.
The dust generated by building (concrete) activities is alkaline and abrasive, and is harmful to cultural relics such as paintings and textile fibers.
Solutions for dust pollution:
For effective preservation, artifacts must be protected from contact with small, aggressive particles. These dusts are usually acidic and are submicron in size. Because molecular filters must be used in conjunction with high-efficiency dust filters. According to EN779: 2002, an F9 end filter must be used. It is also required that the filter has a high initial efficiency and that it remains efficient throughout its life cycle. The "static efficiency" of the EN779: 2002 standard indicates that the permeability of F9 filters is less than half that of F7 filters.