Non-ionizing radiation refers to electromagnetic radiation such as ultraviolet, light, infrared, and radiowaves, and mechanical waves such as infra- and ultrasound.

The International Commission on Non-Ionizing Radiation Protection (ICNIRP) gives recommendations on limiting exposure for the frequencies in the different NIR subgroups. It develops and publishes Guidelines, Statements, and reviews used by regional, national, and international radiation protection bodies, such as the World Health Organization. ICNIRP is a main contributor to the international scientific NIR dialogue and the advancement of NIR protection.

ICNIRP Recommendations are given here: http://www.icnirp.org/en/frequencies/index.html

Intensity less than few mW/cm2 is safe. For workers and public there are different limits. We are sea of radiation. Mobile towers microwaves and so on. It heats tissues causes irritation and so on at high values. What we encounter is much lower than limit. You can check sar value for ur mobile. 

According to US Department of Labor, non-ionizing radiation is described as a series of energy waves composed of oscillating electric and magnetic fields traveling at the speed of light. Non-ionizing radiation includes the spectrum of ultraviolet (UV), visible light, infrared (IR), microwave (MW), radio frequency (RF), and extremely low frequency (ELF). Lasers commonly operate in the UV, visible, and IR frequencies. Non-ionizing radiation is found in a wide range of occupational settings and can pose a considerable health risk to potentially exposed workers if not properly controlled.

Extremely Low Frequency Radiation (ELF)

Extremely Low Frequency (ELF) radiation at 60 HZ is produced by power lines, electrical wiring, and electrical equipment. Common sources of intense exposure include ELF induction furnaces and high-voltage power lines.

Radiofrequency and Microwave Radiation

Microwave radiation (MW) is absorbed near the skin, while Radiofrequency (RF) radiation may be absorbed throughout the body. At high enough intensities both will damage tissue through heating. Sources of RF and MW radiation include radio emitters and cell phones.

Infrared Radiation (IR)

The skin and eyes absorb infrared radiation (IR) as heat. Workers normally notice excessive exposure through heat sensation and pain. Sources of IR radiation include furnaces, heat lamps, and IR lasers.

Visible Light Radiation

The different visible frequencies of the electromagnetic (EM) spectrum are "seen" by our eyes as different colors. Good lighting is conducive to increased production, and may help prevent incidents related to poor lighting conditions. Excessive visible radiation can damage the eyes and skin.

Ultraviolet Radiation (UV)

Ultraviolet radiation (UV) has a high photon energy range and is particularly hazardous because there are usually no immediate symptoms of excessive exposure. Sources of UV radiation include the sun, black lights, welding arcs, and UV lasers.

Laser Hazards

Lasers typically emit optical (UV, visible light, IR) radiations and are primarily an eye and skin hazard. Common lasers include CO2 IR laser; helium - neon, neodymium YAG, and ruby visible lasers, and the Nitrogen UV laser.

Non-Ionizing  radiation  (NIR)  refers  to  radiative  energy  that,  instead  of  producing  charged ions when passing through matter, has sufficient energy only for excitation. Non-ionizing radiation dose not penetrate deep in to the tissue but increases the risk of damage the skin and eyes. Dependent on the energy and exposure time, non-ionizing radiation can cause heating, or photo-chemical reactions can occur with possible permanent harm. Exposure should therefore be minimized. Inappropriate or incorrect use and a wrong design increase the chances of physical harm. Worldwide the maximum acceptable radiation level varies from 10 mW/cm2 to 0.1 mW/cm2

see this paper 

A series of the following recent papers may be interesting, proposing that 207-nm ultraviolet (UV) light (more broadly, far UVC light in the range of 200-222 nm) has similar antimicrobial properties as conventional germicidal UV lumps (254 nm), but without inducing mammalian skin damage due to the shorter penetration depth.

https://www.researchgate.net/publication/258066514_207-nm_UV_Light_-_A_Promising_Tool_for_Safe_Low-Cost_Reduction_of_Surgical_Site_Infections_I_In_Vitro_Studies

https://www.researchgate.net/publication/303872253_207-nm_UV_Light-A_Promising_Tool_for_Safe_Low-Cost_Reduction_of_Surgical_Site_Infections_II_In-Vivo_Safety_Studies

https://www.researchgate.net/publication/313901792_Germicidal_Efficacy_and_Mammalian_Skin_Safety_of_222-nm_UV_Light

Article 207-nm UV Light - A Promising Tool for Safe Low-Cost Reducti...

Article 207-nm UV Light—A Promising Tool for Safe Low-Cost Reduction...

Article Germicidal Efficacy and Mammalian Skin Safety of 222-nm UV Light

visit

http://www.icnirp.org/ 

for scientific informations on non ionizing  radiation and its effect.