What are respirators Surgical or washable cloth masks are no protection against air pollution. Mask unless forms a complete seal is useless. Cloth masks are only marginally beneficial in protecting individuals from particles 2.5 8201 956 m. Journal of Exposure Science and Environmental Epidemiology. 2017 May 27 3 352 357 Particulate respirators are not air purifying respirators as these allow gases to pass through. Since airborne biological agents such as bacteria or viruses are particles they can be filtered by particulate respirators. Particulate respirators are the simplest least expensive and least protective of the respirator types available. These respirators only protect against particles. They do not protect against chemicals gases or vapours and are intended only for low hazard levels. Respirators come with cartridges which need to be changed. Respirators that filter out at least 95 of airborne particles during worse case testing using a most penetrating sized particle are given a 95 rating. Those that filter out at least 99 receive a 99 rating. And those that filter at least 99.97 essentially 100 receive a 100 rating. The commonly known N 95 filtering face piece respirator is one type of particulate respirator often used in hospital to protect against infectious agents. Respirators in this family are rated as N R or P for protection against oils. This rating is important in industry because some industrial oils can degrade the filter performance so it doesn t filter properly. Respirators are rated N if they are Not resistant to oil R if somewhat Resistant to oil and P if strongly resistant oil Proof . Thus there are nine types of disposable particulate respirators https www.cdc.gov niosh npptl topics respirators factsheets respsars.html N 95 N 99 and N 100 R 95 R 99 and R 100 P 95 P 99 and P 100 The N series respirators are commonly not resistant to oil and hence they provide protection against the solid and liquid aerosols that do not contain oil. It is also important to note that the N series respirators have a non specific service life and can be used as long as the mask is not damaged or there is no resistance in breathing. N95 respirators guard against small particles they do not combat another form of traffic related pollution gases like nitrogen oxides or volatile organic compounds. IMA only recommend the use of respirators in lung and heart patients. People with respiratory and cardiac conditions should be warned to remove these if these increase breathing difficulty. N 95 is a mask not respirator. If you have a beard mask is useless. If after initial use you start feeling difficulty in breathing it may be that mask pores have clogged due to high levels of particles in the air. We are fortunate so far that ozone and sulfur dioxide levels are under control Our exposure to air pollution while in car on a main street is fifteen fold higher than a pedestrian walking on pavement. One should stop using car and use Metro. Metro is the safest mode of travel as in many stretches it is underground. With inputs from T K Josh Member CPCB Task Force on Air pollution constituted on the direction of Hon Supreme Court.