For high temperature and high humidity environment, it will be more comfortable to choose a mask with an exhalation valve. Choosing a mask that can remove ozone for welding can provide additional protection. However, if the ozone concentration is higher than 10 times of the occupational health standard, you can replace the mask and combine the dust filter. For the environment with no particulate matter and only some peculiar smell, choosing a dust mask with an activated carbon layer is much lighter than wearing a gas mask, such as some laboratory environments. However, because the national standard does not stipulate the technical performance of this kind of mask, it is best to try it first to judge whether it can really filter the odor effectively.
Whether the dust mask really plays a protective role, in addition to choosing the protective function, another important selection factor is suitability. There is no one-size-fits-all design that can suit everyone's face. At present, the certification test of dust mask cannot guarantee that the mask is suitable for every specific user. If there is a leak, pollutants in the air will enter the breathing area from the leak. The way to choose a suitable mask is to use fitness test, using human taste, and using special tools to produce bitter or sweet particles. If you can still feel the smell after wearing the mask, it means that the mask is leaking. See the introduction of physical fitness test in GB/T 18664 for details.