Some chemicals are extremely dangerous in this respect, and small amounts can cause death or severe injury very quickly. Some, such as chlorine or ammonia, give considerable warning, but others, such as carbon monoxide, are not readily detected and consequently are more insidious. Other toxicological effects of chemicals may be delayed or develop only after exposure over long periods of time and are referred to as chronic. These effects may involve cumulative damage to many different organs or parts of the body. Some are reversed on elimination of exposure to the chemical, but some are nearly irreversible, especially after much damage has occurred.
Carcinogenic effects are usually chronic effects.
HEPA High Efficiency Particulate Air filters. Highly effective for the removal of sub-micron size particles. National Sanitation Foundation Standard performance test requires that penetration of dioctylphthalate particles of 0.3 micrometers diameter shall not exceed 0.01 percent. IARC International Agency for Research on Cancer, World Health Organization, Geneva, Switzerland. One of three sources that OSHA refers to for data on a material's carcinogenicity.