It is natural that with the threat of biological or chemical terrorism comes a lot of talk about gas masks. Before making a decision to buy and use a gas mask, it's important to understand the technology behind various types of equipment available. It is also important to understand that the gas mask alone will not provide adequate protection from biological or chemical contamination. There are different types of gas mask available that serve different purposes. You can search more about the best gas masks via https://www.gasmaskpro.com/
Even the use of a protective suit will only provide protection from air contaminants. The only way to be fully protected is to use a suit that entirely covers the user and seals airtight, which means the use of SCBA gear is required. Unfortunately, this type of gear is very expensive and impractical for civil use. You should not expect to be able to stay in an affected area for any period of time without this type of gear.
See various types of gas masks
The least effective type of gas mask is known as a half mask air purifier respirator. This covers the nose and mouth that allows users to breathe through the mask filtration system. However, many chemical and biological agents use the eyes as the entry point, causing contamination.
The more effective type of mask is known as a full-face air purifier respirator. These Gas Masks provide a clear face mask or clear eyepieces that protect the eyes, as well as the nose and mouth. The issue with these air-purifying respirators is that they may leak from either a poor fit or from a crack or hole on the mask.
Solving the leak problem is the supplied-air respirator. These use the same sort of filter attached to a battery-operated canister with a fan forcing air through it. The advantage is the positive pressure created by the system ensuring that any leak in the mask releases purified air rather than allowing contaminated air from the environment to enter.