4.1.2 Classification of skin protective products
Skin protective products includes personal protective equipment（PPE）and skin protective agents.
1.PPE
PPE refers to the items that operators wear at work，e.g.，protective masks，work clothes and gloves（Figure 4-1），in order to avoid or reduce accidental injuries and occupational hazards.
When classified by the use objectives，PPE includes：individual protective equipments for military personnel，such as bullet-proof helmets，bullet-proof clothing，gas masks，and combat boots；protective equipments for police，such as explosion-proof clothing，anti-stab clothing，and anti-glare glasses；protective equipments for diverse types of workers，mainly industrial and agricultural production staff，medical staff，and scientific and technological workers.
When classified by the protection objectives，PPE includes：physical protective equipments such as insulating gloves，hardhats，and earmuffs；chemical protective equipments such as gas masks，acid-proof clothing，and alkali-proof clothing；biological protective equipments such as medical masks，goggles，and medical protective clothing；public safety protective equipments for public places，such as escape masks and life jackets in civil aviation passenger planes；protective equipments used in personal life，such as anti-haze and anti-UV goggles.
When classified by the protected body parts，PPE includes respiratory protectors，eye shields，face shields，ear protectors，helmets，protective clothing，gloves，and shoe covers.
In short，personal protective equipment is combined with the specific working environment to protect workers' mouth，nose，eyes，ears，exposed skin and other vulnerable parts such as inhalation，absorption and head.
2.Skin protective agents
Skin protective agents mainly include protective ointment，skin cleanser，skin protective films，skin cream and moisturizing protective ointment.(https://www.daowen.com)
（1）Protective ointment：Protective ointment is a kind of skin care preparation to prevent harmful substances from acting on exposed skin and occupational skin diseases.The protective ointment is soluble or insoluble in water，and its function is to apply to the skin and become a viscous coating or a flexible film，thus playing a mechanical or special protective role on the skin.For example，protective ointment can play the roles in redox，neutralization，complexation and absorption of harmful substances.Long-term use of protective ointment can play a certain role of isolation，so that the skin can be protected.Common protective ointment includes hydrophilic protective ointment，hydrophobic protective ointment and sunshade protective ointment，and others.
①Hydrophilic protective ointment：It contains less oil and is applied to the surface of the skin when it is used.This kind of ointment can play the role of oil resistance and is used in contact with mineral oil，organic acid and other operations.
②Hydrophobic protective ointment：It contains a lot of oil and is applied to the surface of the skin and can plug pores.This kind of ointment prevent individuals from the splashing injuries of water-soluble substances，such as low concentration of acid，alkali and salt liquid.
③Sunshade protective ointment：It can help to avoid light after smearing.It is mainly used to prevent the irritation of photosensitive substances such as asphalt and tar to the skin.It is suitable for tar，asphalt，electric welding and snow operation.Sunscreen that people use daily is also one of them.
（2）Skin cleanser：Skin cleanser is mainly used to wash all kinds of pollution on the surface of the skin，especially for workers exposed to poison and dust，when it is necessary to clean up and remove the poison on the attached skin and overalls in time.The most commonly used skin cleanser is soap，but many chemicals exposed to work are not easily washed by soap，and soap will damage part of the skin fat when washed.Organic solvents can be used to wash away stubborn stains such as gasoline，kerosene and turpentine，but these cleansers themselves can cause or aggravate skin damage.
（3）Skin protective films：Skin protective films are also known as invisible gloves，which are usually made of cellulose，casein or rosin dissolved in alcohol.The skin protective films can be applied to the surface of the skin to form an oil-resistant，water-resistant and irritant film，which is suitable for irritating work such as electroplating，paint，printing，dyeing and dust.
（4）Skin cream and moisturizing protective ointment：This kind of ointment contains a lot of oil，and it is usually added with substances such as high protein，royal jelly and pearl powder that are easily absorbed by the human body to increase the effects of moisturizing and protecting the skin.It is suitable for preventing defatting of skin caused by long-term contact with water，alkaline solution and organic solvent.
Compared with the defects of PPE（e.g.，lack of tightness，leakage，affecting work and discomfort），skin protective agents are lighter and can come into close contact with the skin.Yet，the protection by skin protective agents may not be as good as PPE.