14 May / June 2019
Why do you Need to Measure BTEX in Ambient Air?
by Dr Carlo Bruno, Pollution Analytical Equipment, Italy Via Guizzardi, 52 – 40054 Budrio (Bologna) – Italy
Accurate and reliable BTEX testing (Benzene, Toluene, Ethylbenzene and Xylenes) is critical in determining the levels of exposure and contamination in the environment. High levels of BTEX exposure can affect human health and the environment, which has resulted in a European Directive and with EPA guidelines to set allowable limits. The World Health Organisation (WHO) considers the exposure to Benzene (even at a very low concentration of part per billion) a major public health concern because human exposure to this VOC has been associated with a range of acute and long-term adverse health effects and diseases (severe effect to the central nervous system, severe damage to the liver, lungs and so on), including cancer and leukaemia. Occupational Safety and Health Administration (OSHA ) recommendation for benzene exposure is very restricted and also the European air quality directive gives the limit value of 1.5 ppb for the annual mean. It also recommends to not exceed 1 ppm as time weighted average (TWA) or 5ppm for short term exposure limit over a period of 15 minutes. The carcinogenic (leukemogenic) potential of benzene is well established as indicated by its consensus classification as a human carcinogen by the National Toxicology Program (NTP 2001), US Environmental Protection Agency (EPA) (IRIS 2001), and International Agency for Research on Cancer (IARC 1987). Ethylbenzene is possibly carcinogenic to humans based on a recent assessment by IARC (2000). Toluene and xylenes have been categorised as not classifiable as to human carcinogenicity by both EPA (IRIS 2001) and IARC (1999a, 1999b), reflecting the lack of evidence for the carcinogenicity of these two chemicals. [1]
BTEX analysis gives a great indication of VOC emissions from an extended range of sources. The primary man‐made sources of BTEX are via emissions from motor vehicles and aircraft exhaust, losses during petrol manufacturing, spills and cigarette smoke. BTEX are created and used during the processing of refined petroleum products and coal; during the production of chemical intermediates and consumer products such as paints and lacquers, thinners, rubber products, adhesives, inks, cosmetics and pharmaceutical products. BTEX compounds are among the most abundantly produced chemicals, with worldwide annual production of 8‐10 million tons of benzene, 5‐10 million tons of toluene, 5‐10 million tons of ethylbenzene and 10‐15 million tons of xylenes.
Benzene for instance, is commonly found throughout the petrochemical industry, vehicle exhaust and burning of solid and liquid fuels. It gives a great indication of the dominance of petrol vehicles in the vehicle fleet, and it is useful as an indicator for home heating emissions from solid fuels. As Benzene occurs naturally in crude petroleum at levels up to 4 g/l, human activities using petroleum (extraction and transport of crude oil, refineries, transport and use of gasoline)
Figure 1: Calibration chromatograms at different span gas concentrations (0-5ppb).
lead to exposure. Therefore personnel on on-board ships that transport crude oil or gasoline or on offshore platforms for well drilling and exploration, extraction, storing and processing petroleum are potentially exposed to those harmful VOCs.
So more generally, the BTEX chemicals are released into the environment either through emissions or leakages. In particular benzene has been recognised as the major source of fugitive emissions and it is very well known to cause cancer even at very low exposure limits.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68
