Organic pollutants
Benzene
Toluene
Xylene
Formaldehyde
Organic substances comprise a potentially large group of air pollutants, particularly in urban environments.
Motor vehicle emissions are a major source of these pollutants together with the petroleum and chemical industries, emissions from waste incinerators, service stations, domestic solid fuel and gas combustion, spray painting, dry-cleaning and other solvent usage, and cigarette smoke.
Even at low levels, some of these organic pollutants can be hazardous to human health, particularly if the exposure is long term. Some organic pollutants also play an important role in the formation of photochemical smog.
The department monitoring measures levels of benzene, toluene, xylene and formaldehyde in southeast Queensland and Gladstone. Motor vehicle and industrial emissions are the predominant sources of these pollutants at the monitoring locations.
Benzene
Benzene is an aromatic hydrocarbon compound. It occurs naturally in fossil fuels and is released into the atmosphere as a result of natural processes, and human activities that involved the combustion of organic matter, such as wood, coal, and petroleum products.
Petrol vehicle emissions are the predominant source of benzene in the environment, although industries such as petroleum refining and steel works can also contribute to overall levels. Evaporative losses from petroleum fuels storage facilities and service stations is another means by which benzene enters the air environment. Tobacco smoke contains benzene and accounts for approximately 50 percent of a person's total exposure.
Health effects
At typical ambient concentrations, benzene does not have any short-term or acute health effects. However long-term exposure to benzene has been linked to an increased incidence of blood and immune system disorders including anaemia and leukaemia
Air quality goal
There is currently no Australian air quality goal for benzene. The United Kingdom air quality strategy objective for benzene is an annual average of 5ppb.
Toluene
Toluene occurs naturally in crude oil and is also generated by combustion of organic matter such as wood, coal and petroleum products. Motor vehicle emissions are the predominant source of toluene in the urban air environment, although evaporative losses from petroleum fuels storage facilities and service stations and the use of toluene based solvents and thinners are other contributors. Toluene is a component of tobacco smoke. The highest concentrations of toluene usually occur in indoor air from the use of household products containing toluene (paints, thinners and adhesives) and cigarette smoke.
Health effects
Health effects associated with toluene exposure primarily relates to central nervous system impairment. There is no evidence that toluene is carcinogenic. Toluene has been linked to hormonal imbalances, which may affect reproduction and foetal development. These effects have only been observed at exposure concentrations significantly higher than typical outdoor levels, either through occupational exposure or deliberate solvent abuse.
Air quality goal
The EPP (Air) goal for toluene is a maximum concentration of 2000 ppb over a 24-hour period.
Xylene
Xylene is an aromatic hydrocarbon that exists in three isomeric forms Ortho, Meta, and Para Xylene. The composition of xylene produced from petroleum is a mixture containing approximately 40 percent m-xylene, 20% o-xylene, 20 percent p-xylene, and 20% ethyl benzene. Xylene occurs naturally in crude oil and is also generated through combustion of organic matter such as wood, coal, and petroleum products. Motor vehicle emissions are the predominant source of xylene in the urban air environment. Evaporation from petroleum fuels storage facilities and service stations, and the use of products containing xylene based solvents and thinners are other ways xylene enters the air environment
Health effects
Xylene exposure causes eye, nose and throat irritation and neurological effects such as impaired reaction time short-term memory loss and the loss of bodily coordination. There is no evidence that xylene is carcinogenic. The above effects do not occur at xylene levels typically experienced in ambient air.
Air quality goal
There is no Australian air quality goal for xylene. The World Health Organization recommends that xylene exposure be kept below 1015ppb over a 24-hour period to safeguard human health.
Formaldehyde
Formaldehyde is a colourless gas with a strong irritant odour. Low levels of formaldehyde are part of naturally occurring decomposition processes. In urban environments formaldehyde emission sources including motor vehicle exhaust, domestic solid fuel and gas combustion releases from goods manufactured using formaldehyde based glues and resins, and tobacco smoke. The last two sources are important indoor air quality issues. In addition, photochemical reactions involving oxidation of hydrocarbon compounds can produce formaldehyde
Health effects
Exposure to moderate levels of formaldehyde (1 to 3 ppm) can result in eye, nose, and upper respiratory tract irritation. Odour annoyance often occurs at lower concentrations. Formaldehyde has been classified as a probable human carcinogen, although it has not been conclusively established that typical ambient concentrations are sufficient to cause cancer.
Air quality goal
The EPP (Air) goal for formaldehyde is a maximum concentration of 70 ppb averaged over a 30 minute period.
Measurement of organic pollutants
EPA measurements of organic pollutants are conducted using DOAS instrumentation.
Last updated: 07 April 2006