Decrements In Peak Expiratory Flow Research Articles

Changes in Lung Function and Airway Inflammation Among Asthmatic Children Residing in a Woodsmoke-Impacted Urban Area

Fine particulate matter (PM2.5) is associated with respiratory effects, and asthmatic children are especially sensitive. Preliminary evidence suggests that combustion-derived particles play an important role. Our objective was to evaluate effect estimates from different PM2.5 exposure metrics in relation to airway inflammation and lung function among children residing in woodsmoke-impacted areas of Seattle. Nineteen children (ages 6–13 yr) with asthma were monitored during the heating season. We measured 24-h outdoor and personal concentrations of PM2.5 and light-absorbing carbon (LAC). Levoglucosan (LG), a marker of woodsmoke, was also measured outdoors. We partitioned PM2.5 exposure into its ambient-generated (Eag) and nonambient (Ena) components. These exposure metrics were evaluated in relation to daily changes in exhaled nitric oxide (FENO), a marker of airway inflammation, and four lung function measures: midexpiratory flow (MEF), peak expiratory flow (PEF), forced expiratory volume in the first second (FEV1), and forced vital capacity (FVC). Eag, but not Ena, was correlated with combustion markers. Significant associations with respiratory health were seen only among participants not using inhaled corticosteroids. Increases in FENO were associated with personal PM2.5, personal LAC, and Eag but not with ambient PM2.5 or its combustion markers. In contrast, MEF and PEF decrements were associated with ambient PM2.5, its combustion markers, and Eag, but not with personal PM2.5 or personal LAC. FEV1 was associated only with ambient LG. Our results suggest that lung function may be especially sensitive to the combustion-generated component of ambient PM2.5, whereas airway inflammation may be more closely related to some other constituent of the ambient PM2.5 mixture.

Association Between PM2.5 and Decrements in Peak Expiratory Flow in COPD Adults in Mexico City

Association Between PM2.5 and Decrements in Peak Expiratory Flow in COPD Adults in Mexico City

Effect of Metalworking Fluid Mist Exposure on Cross‐Shift Decrement in Peak Expiratory Flow

Exposure to metalworking fluids (MWF) mist and cross-shift decrements in peak expiratory flow (PEF) were evaluated and their relationship was analyzed using several statistical methods. The objective of this study was to assess workers, exposure to MWF mineral mist and to find the MWF mist level for predicting cross-shift decrements in PEF. A total of 158 workers handling water-soluble MWF had MWF mist exposures with an arithmetic mean (AM) of 0.4 mg/m(3) (range: LOD-13.5 mg/m(3)), and 9.2% of workers (219) showed a cross-shift decline greater than 10% in PEF. MWF mist exposure and cross-shift decrements in PEF that were matched (n=113) were linearly significantly associated (R(2)=0.036, p=0.045) although the correlation was quite weak (r=0.189). We found a slight increase in cross-shift decrements in PEF with increased exposure to MWF aerosol mass concentration. The MWF mist exposure level was categorized into two or three groups by the cutoffs of either the National Institute for Occupational Safety and Health's Recommended Exposure Level (NIOSH REL: 0.5 mg/m(3)) or the American Conference of Governmental Industrial Hygienists Notice of Intended Change (ACGIH NIC: 0.2 mg/m(3)). The cross-shift decrement in PEF observed from workers exposed to > or =0.2 mg/m(3) was slightly higher than that of the exposure level of < or =0.2 mg/m(3) at p=0.207 while significant differences among categorized exposure groups (2 categories, <0.5 and > or =0.5 mg/m(3), or 3 categories, <0.2, 0.2-0.5 and > or =0.5 mg/m(3)) were not detected. In order to find out whether there is a specific level that allows us to predict cross-shift decrements in PEF, several statistical models were constructed. Logistic regression showed that the MWF concentration, whether treated as a continuous variable or a categorical variable, was not significantly associated with cross-shift decrements dichotomized by a cutoff of either 10% or 15% in PEF. We couldn't find evidence of a significant PEF decrement increase with increasing exposure category. Thus, we concluded that PEF decrements measured in workers exposed to MWF mist concentrations greater than either 0.2 mg/m(3) or 0.5 mg/m(3) was not significantly different from those found in workers exposed to lower MWF mist concentrations. Further study is needed to establish the level of MWF mineral mist predicting non-malignant respiratory health effects.

Interaction between ozone and airborne particulate matter in office air

This study investigated the hypotheses that humans are affected by air pollution caused by ozone and house dust, that the effect of simultaneous exposure to ozone and dust in the air is larger than the effect of these two pollutants individually, and that the effects can be measured as release of cytokines and changes of the respiratory function. Experimental exposures of eight atopic but otherwise healthy subjects were performed in a climate chamber under controlled conditions. The three controlled exposures were about 75 microg/m3 total suspended particulate matter, 0.3 p.p.m. ozone, and the combination of these. The exposure duration was 3 h. The outcome measures were interleukins and cells in nasal lavages (NAL), respiratory function, bronchial metacholine responsiveness, rhinometry symptoms and general well-being in a questionnaire and time course of general irritation on a visual analogue scale. Indications of interactions between exposure types were demonstrated for peak expiratory flow (PEF) (P<0.05) and for discomfort symptoms (P<0.03). Non-significant interactions were found for the concentration of interleukin-8 in NAL. The combined exposure was found to cause significantly more effects than either ozone exposures or dust exposures. This is interpreted as indications of a potentiation caused by the combined exposures to dust and ozone. The findings in this study are based on a limited number of subjects and thus should not be over-interpreted. However, they support the hypothesis that ozone at relatively high concentrations interacts with dust exposures to cause decrements in PEF and increase in discomfort measures. If confirmed at lower ozone and dust concentrations this finding could help to explain many problems with indoor air quality reported in offices throughout the world.

Acute effects of urban air pollution on respiratory health of children with and without chronic respiratory symptoms.

OBJECTIVES: To investigate to what extent different components of air pollution are associated with acute respiratory health effects in children with and without chronic respiratory symptoms. METHODS: During three consecutive...

Healthy women's PEF variations with ambient summer concentrations of PM10, PM2.5, SO42-, H+, and O3.

The relationship between ambient air pollution and daily change in peak expiratory flow (PEF) was studied in a sample of 473 nonsmoking women (age 19 to 43 yr) in Virginia over summers 1995- 1996. Daily 24-h averages of particulate matter (PM2.5 and PM10), fine particulate sulfate (SO42-) and strong acid (H+), hourly ozone (O3), and select meteorologic variables (e.g., temperature) were collected at a regional outdoor monitoring site. Subjects took PEF measurements twice daily for a 2-wk period using a standard MiniWright peak flow meter. Concurrent measures for summer periods of 24-h PM2.5 (micrograms/m3) ranged from 3.5 to 59.7; H+ (nmol/m3) from 0 to 250; maximal daily 8-h average O3 (ppb) from 17.0 to 87.6. Morning PEF decrements were significantly associated with H+ and PM2. 5. An increase of 50 etamol/m3 of H+ and 10 micrograms/m3 of PM2.5 related to decreases of 0.89 (95% CI = 0.21 to 1.57) and 0.73 (95% CI = 0.07 to 1.38) L/min in morning PEF, respectively. Ozone was the only exposure related to evening PEF with 5-d cumulative lag exposure showing the greatest effect; 7.65 L/ min (95% CI = 2.25 to 13.0) decrease per 30 ppb O3 increase. Separate physiologic effects were observed for summer ambient concentrations of two different pollutants (PEF decrements related to PM2.5 in morning and O3 in evening) at concentrations below the new U.S. EPA 24-h ambient air quality standard for PM2.5 and 8-h standard for O3.

Modulation of the acute respiratory effects of winter air pollution by serum and dietary antioxidants: a panel study.

This study investigated whether a high dietary intake or serum concentration of antioxidant (pro-) vitamins could attenuate the acute respiratory effects of air pollution in panels of adults (n = 227) aged 50-70 yrs with chronic respiratory symptoms in two winters starting in 1993/1994. Subjects performed daily peak expiratory flow (PEF) measurements in the morning and evening and reported the occurrence of respiratory symptoms in two regions (urban and nonurban) each winter. Logistic regression analysis was used with the prevalences of large PEF decrements as dependent variables and air pollution levels as independent variables. Analyses were performed separately for subjects below and above the median levels of serum beta-carotene and the intake of dietary vitamin C and beta-carotene. Subjects with low levels of serum beta-carotene more often had large PEF decrements when particles <10 microm in diameter or black smoke levels which were higher compared to subjects with high levels of serum beta-carotene. The same results tended to be observed for dietary vitamin C or beta-carotene, but there were less significant air pollution effects in the low dietary antioxidant group. The results suggest that serum beta-carotene and to a lesser extent dietary vitamin C and beta-carotene may attenuate peak expiratory flow decrements due to air pollution in subjects with chronic respiratory symptoms.

Association between PM10 and decrements in peak expiratory flow rates in children: reanalysis of data from five panel studies.

Panel studies have found 1-3% increases in reports of acute respiratory symptoms associated with each 10 microg x m(-3) increase in ambient concentrations of particles with a 50% cut-off aerodynamic diameter of 10 microm (PM10). Statistically significant decrements in population mean peak expiratory flow (PEF) have also been observed but their magnitude is only about 0.1% for the same exposure. This study evaluated whether this difference is due to the different measurement scales used for the expression of the effects of air pollution on PEF and respiratory symptoms. The association between the prevalence of large decrements in PEF (more than 10% or 20% below the median) and PM10 concentrations was analysed using data from five recent panel studies. The effect estimates were compared to the effect estimates from original studies based on the population mean PEF. The decrement in the population mean PEF for an increase of 10 microg x m(-3) of the same-day PM10 concentration was 0.07%, averaged over all panels. A significant relative increase of 2.7% (95% confidence interval 1.6-3.8) in the prevalence of PEF decrements greater than 10% was associated with the same exposure. In conclusion, defining the peak expiratory flow response by the prevalence of large decrements provides effect estimates of a comparable magnitude to effect estimates for the prevalence of reports of acute lower respiratory symptoms.

Reversible pulmonary responses to formaldehyde. A study of clinical anatomy students.

Epidemiologic studies of irritants are difficult to perform using standard epidemiologic methods for several reasons, including the reversible nature of the health outcomes, the selection of sensitive individuals from the study population, and the wide heterogeneity in normal responses to irritants. This study examined the feasibility of using repeated measurements of peak expiratory flow (PEF) and reported symptoms to study respiratory irritants and their effects in students exposed to formaldehyde during a clinical anatomy laboratory course. We studied 24 physical therapy students dissecting cadavers for 3 h per week over a 10-wk period. Formaldehyde exposures in the breathing zone ranged from 0.49 to 0.93 ppm (geometric mean +/- geometric SD, 0.73 +/- 1.22). Irritant symptoms increased strongly over the course of the average laboratory period, but this effect was stronger at the beginning than at the end of the semester. PEF measured before each laboratory session declined over the semester by an average of about 10 L/min (2% of baseline), a trend that was statistically significant in random-effects regression models. After 14 wk away from the laboratory, the group's mean baseline PEF had returned to its preexposure level. Mean PEF also declined over each laboratory period, although this effect was attenuated over the course of the semester. Other important predictors of cross-laboratory PEF decrements were asthma and reporting throat irritation during the laboratory. It appears that mild irritant effects can be detected in naive subjects using a repeated monitoring design and relatively simple instrumentation.