The purpose of this review is to discuss the debate concerning the interpretation of epidemiologic studies on particles and health effects. Study of the 1952 air pollution disaster in London established that very high levels of particulate-based smog can cause dramatic increases in daily mortality. However, recent epidemiologic studies have reported statistically significant health effects and mortality due to low levels of air pollution. The statistical significance does not prove causation in observational studies; therefore it is necessary to evaluate these associations. There are arguments for and against each of the numerous studies using Hill's criteria, however the body of accepted evidence supports the causal association. In particular, a high level of consistency in the estimated effect of PM10 has been observed across studies worldwide. The mechanism of the relationship between air pollution and health effects is not obvious. The mechanism of particle-induced injury may involve the production of an inflammatory response by the particulate. The harvesting and the threshold effect are also major concerns regarding the health effects of air pollution. However, current epidemiologic findings indicate that linear models lacking a threshold are appropriate for assessing the effect of particulate air pollution on daily mortality even at current levels.
Air Pollution* ; Disasters ; Epidemiologic Studies* ; Linear Models ; Mortality ; Smog

Air Pollutants ; Air Pollution ; Humans ; Particulate Matter ; Public Health ; Smog

BACKGROUND AND OBJECTIVES: Ozone is the principal oxidant pollutant in photochemical smog. Although ozone-induced pulmonary changes have been morphologically characterized, effects of ozone on the upper respiratory tract have not been thoroughly investigated. The purpose of this study was to investigate the morphological change of nasal mucosa after acute exposure to ozone. MATERIAL AND METHODS: Rats are exposed to 0.3, 0.6, 0.9, and 1.2 ppm of 0, for 6 hours a day for 7 days. Rats were sacrificed 18h after the end of their last exposure. Nasal mucosa was processed for Hematoxylin/Eosin (H/E) stain and Alcian blue (pH 2.5)/Periodic Acid Schiff (AB/PAS) stain. RESULTS: Morphological changes such as infiltration of neutrophils, loss of cilia, epithelial hyperplasia, squamous metaplasia and secretory cell metaplasia were observed and these changes were more pronounced in the group exposed to high concentration of ozone, compared with the group exposed to low concentration. CONCLUSION: The results of this study may suggest that ozone exposure induces infiammatory, proliferative, and metaplastic responses in the nasal mucosa.
Alcian Blue ; Animals ; Cilia ; Hyperplasia ; Metaplasia ; Nasal Mucosa* ; Neutrophils ; Ozone* ; Rats* ; Respiratory System ; Smog

OBJECTIVETo study the method of concentration determination of mineral-oil fog in the air of workplace.

METHODSFour filter films such as synthetic fabric filter film, beta glass fiber filter film, chronic filter paper and microporous film were used in this study. Two kinds of dust samplers were used to collect the sample, one sampling at fast flow rate in a short time and the other sampling at slow flow rate with long duration. Subsequently, the filter membrane was weighed with electronic analytical balance. According to sampling efficiency and incremental size, the adsorbent ability of four different filter membranes was compared.

RESULTSWhen the flow rate was between 10 approximately 20 L/min and the sampling time was between 10 approximately 15 min, the average sampling efficiency of synthetic fabric filter film was 95.61% and the increased weight ranged from 0.87 to 2.60 mg. When the flow rate was between 10 approximately 20 L/min and sampling time was between 10 approximately 15 min, the average sampling efficiency of beta glass fiber filter film was 97.57% and the increased weight was 0.75 approximately 2.47 mg. When the flow rate was between 5 approximately 10 L/min and the sampling time between 10 approximately 20 min, the average sampling efficiency of chronic filter paper and microporous film was 48.94% and 63.15%, respectively and the increased weight was 0.75 approximately 2.15 mg and 0.23 approximately 0.85 mg, respectively. When the flow rate was 3.5 L/min and the sampling time was between 100 approximately 166 min, the average sampling efficiency of filter film were 94.44% and 93.45%, respectively and the average increased weight was 1.28 mg for beta glass fiber filter film and 0.78 mg for beta glass fiber filter film and synthetic fabric synthetic fabric filter film. The average sampling efficiency of chronic filter paper and microporous film were 37.65% and 88.21%, respectively. The average increased weight was 4.30 mg and 1.23 mg, respectively.

CONCLUSIONSampling with synthetic fabric filter film and beta glass fiber filter film is credible, accurate, simple and feasible for determination of the concentration of mineral-oil fog in workplaces.

Air ; analysis ; Air Pollutants, Occupational ; analysis ; Filtration ; instrumentation ; Mineral Oil ; analysis ; Smog ; analysis ; Workplace

OBJECTIVETo investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators.

METHODSSeventy electric arc welding operators (WOs) and 70 healthy volunteers (HVs) were enrolled in a randomized controlled study design, in which the levels of vitamin C (VC) and vitamin E (VE) in plasma as well as the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and the level of lipoperoxide (LPO) in erythrocytes were determined by spectrophotometry.

RESULTSCompared with the average values of the above experimental parameters in the HVs group, the average values of VC and VE in plasma as well as those of SOD, CAT and GPX in erythrocytes in the WOs group were significantly decreased (P < 0.005-0.0001), while the average value of LPO in erythrocytes in the WOs group was significantly increased (P < 0.0001). The findings from the partial correlation analysis on the controlling of age suggested that with a prolonged duration of exposure to photochemical smog the values of VC, VE, SOD, and GPX, except for CAT, in the WOs were decreased gradually (P < 0.05-0.005), the value of LPO in the WOs was increased gradually (P < 0.001), and that with the ozone dose increased in the air in each worksite VC, VE, SOD, CAT and GPX decreased (P < 0.005-0.001), but LPO increased (P < 0.001). The findings from the reliability analysis for the VC, VE, SOD, CAT, GPX, and LPO values which were used to reflect oxidative stress and potential oxidative damage in the WOs showed that the reliability coefficients' alpha (6 items) was 0.8021, P < 0.0001, and that the standardized item alpha was 0.9577, P < 0.0001.

CONCLUSIONFindings in the present study suggest that there exists an oxidative stress induced by long-term exposure to photochemical smog in the bodies of WOs, thereby causing potential oxidative and lipoperoxidative damages in their bodies.

Adult ; Antioxidants ; metabolism ; Ascorbic Acid ; blood ; Catalase ; blood ; Erythrocytes ; metabolism ; Glutathione Peroxidase ; blood ; Humans ; Lipid Peroxides ; blood ; Middle Aged ; Nitric Oxide ; blood ; Oxidants, Photochemical ; adverse effects ; analysis ; Oxidative Stress ; Ozone ; analysis ; toxicity ; Risk Assessment ; Smog ; Superoxide Dismutase ; blood ; Vitamin E ; blood ; Welding