Air Toxics

Hazardous Air Pollutants (HAPs or "air toxics") are regulated under the Clean Air Act.  Ambient air quality standards do not exist for HAPs.  Instead, the Clean Air Act requires the EPA to establish Maximum Achievable Control Technology (MACT) standards for facilities that emit these pollutants.  A complete list of HAPs can be found here

Ethylene Oxide (EtO)

EPA classified ethylene oxide (EtO) as a human carcinogen in December 2016.  EtO is a colorless, flammable gas used in the manufacture of a number of chemical products and the sterilization of equipment that cannot be sterilized by steam.  The EPA updated its emission standards for Miscellaneous Organic Chemical Manufacturing (also known as the "MON") in August 2020 and specifically added monitoring and operational requirements for  control of EtO.  

Per- and Polyfluoroalkyl Substances (PFAS)

Per- and polyfluoroalkyl substances (also known as PFAS) are a class of man-made chemicals used for a number of purposes, such as the manufacture of Teflon™ and in common firefighting foams.  The EPA and state agencies are actively investigating the true extent of PFAs contamination in the environment and the potential risks to human health; however, evidence suggests manufacturing and incineration activities are significant pathways for PFAS to the environment.  PFAS is not currently a listed HAP, but it is an emerging pollutant of concern.  


Fumigants are chemicals used to apply smoke, vapor, or gas especially for the purpose of disinfecting or destroying pests.  The EPA has identified a number of fumigants of particular concern.  

Methyl Bromide

Methyl bromide is a fumigant used to control pests in agriculture and is a known ozone depleting substance.  The United States has phased out production and consumption of methyl bromide with important exceptions for critical uses, quarantine, and pre-shipment.  


Phosphine fumigants are widely used on farms to control insect and rodent infestation in many different stored grains.  Inhalation of phosphine vapors is toxic and can cause poisoning.  

Sulfuryl Fluoride

Sulfuryl fluoride is a toxic gas which acts as a central nervous system depressant and is used to fumigate stored food commodities.  

Hydrochloric Acid (HCl)

Hydrochloric acid (also known as muriatic acid) is used in a variety of industrial processes in Linn County, such as:  pickling and cleaning of metal products, electroplating, and the combustion of fossil fuels.  HCl is classified as a hazardous air pollutant and is corrosive to eyes, skin, and mucous membranes.  


Acetaldehyde is mainly used as an intermediate in the synthesis of other chemicals and can be formed in the human body during the breakdown of ethanol (alcohol).  Short-term exposure to acetaldehyde can result in irritation of the eyes, skin, and respiratory tract.  Symptoms of long-term exposure can resemble those of alcoholism.