These data showed that workers exposed to VOCs with atopy or that were smokers had a higher AHR in comparison to the non-atopy, non-smoking VOC exposed workers.
The relationship between allergens in the indoor environment and asthma has been extensively studied and recent studies have suggested the possibility of the role of chemical pollutants for the genesis of asthma in the occupational environment.
The organic chemicals found in indoor air can be grouped by their range of boiling points as volatile (0 to 240
), semivolatile (240 to 380
), and particulate (over 380
. The volatile and semivolatile organic chemicals are most relevant to human health. VOCs exist as vapors over the normal range of air temperature and pressures, whereas semivolatile organic chemicals are liquids or solids, but they also evaporate slowly17)
Despite the potential risks of the organic chemicals in the work environment, few studies2
have shown specific disease-exposure associations.
VOCs at concentrations found in both work and home environments may influence the functioning of lungs and they are probably important as bronchial irritants7)
. Yet the residential indoor and outdoor VOC concentrations measured in Seoul were significantly higher than those found in Asan, suggesting that the VOC levels are higher in polluted area in comparison with the less polluted area19)
Indoor exposure to tobacco smoke, some VOCs and various combustion products (either by using unvented stoves or from outdoor sources) can be related to asthmatic symptoms. In this study, exposed workers with smoking or atopy had a higher BRindex, suggesting that smoking is an important additive factor to VOCs in relation to AHR. In some susceptible individuals, the development of respiratory hypersensitivity or the elicitation of asthmatic symptoms may also be related to the indiscriminate use of different household products and then this is followed by exposure to such compounds as diisocyanate, organic acid anhydrides, formaldehyde, styrene and hydroquinone20)
. The VOC emissions from solvent-based paints might contribute to the development of respiratory symptoms and airway irritation7)
. There are probably some patients with an increased sensitivity to paint fumes who would derive a useful symptomatic benefit from using VOC-free paint20)
. Some of the VOCs emitted by rape-seed oil have the potential to be allergens/irritants21)
. In this study, there was no difference of AHR between the workers exposed to VOCs and the control subjects. Further, there was no AHR difference between the atopy and non-atopy workers exposed to VOC. The absence of AHR differences maybe due to the study population and the low VOC concentrations, as compared to the previous study of Ware et al23)
. Further studies with larger subject pools are needed to clarify the relation between workers exposed to VOCs and the control subjects. Although there were no differences of AHR between the workers exposed to VOCs with atopy and the workers exposed to VOCs with smoking and the control subjects, the workers with atopy or smoking showed increased AHR, suggesting that VOCs might contribute as an aggravating factor of AHR.
Exposure to chemical emissions from indoor paint is related to asthma, and some VOCs may cause inflammatory reactions in the airways18)
. Significant relationships have been noted between nocturnal breathlessness and the presence of wall-to-wall carpets, and the indoor concentrations of CO2
, formaldehyde and VOCs. AHR is related to the indoor concentration of limonene, which is the most prevalent terpene. Variability in the peak expiratory flow rates is related to two other terpenes: alpha-pinen and delta-karen. This suggests that indoor VOCs and formaldehyde may cause asthma-like symptoms22)
. The incidence of chronic respiratory symptoms is also positively associated with the concentrations of volatile organic compounds, considering that exposure to volatile organic compounds, including the emissions from chemical manufacturing plants, is associated with increased rates of chronic respiratory symptoms that are characteristic of reactive airways23)
. For improving the management of asthma and to counteract the increasing frequency of asthma, the significance of the work environment can not be neglected18)
However, because of the selection effects, the results of cross-sectional studies on respiratory symptoms in relation to occupational exposure to VOC emissions may be inconclusive. Despite the small size of the worker groups in this study, significant differences in the AHR of the workers exposed to VOCs with atopy or smoking were detected, and this suggests that VOCs may increase AHR. Further prospect studies with larger populations of workers should be done.
In the present study, any association between VOCs and AHR was not seen, but when this was adjusted for smoking or atopy, the association with VOC exposure was evident. Therefore, there is a need to decrease people's exposure to VOCs and to improve the air supply in the work environment. Improved work environment can also be achieved by selecting proper building materials and paying close attention on the various options and choices when constructing a building. The emission of VOCs should be as low as reasonably achievable to minimize the asthma-related symptoms that are due to polluted air in the work environment.
In conclusion, this study indicated that the workers exposed to VOCs with atopy or that are smokers have increased AHR as compared to workers exposed to VOCs with non-atopy and that are non-smokers, in one Korean petrochemical plant. Therefore, volatile organic chemicals should be well ventilated during use in occupational and home environments to reduce the occurrence of asthma-related symptoms.