Increased fine particle deposition in women with asymptomatic nonspecific airway hyperresponsiveness

The Impact of Air Pollution on Asthma Severity among Residents Living near the Main Industrial Complex in Oman: A Cross-Sectional Study

BACKGROUND

Asthma is a widespread chronic respiratory disease that poses a significant public health challenge. The current study investigated the associations between air pollution and asthma severity among individuals residing near the Sohar industrial port (SIP) in Oman. Despite the presence of multiple major industrial complexes in Oman, limited knowledge regarding their impact on respiratory health is accredited. Hence, the primary objective of this study is to offer valuable insights into the respiratory health consequences of industrial air pollution in Al Batinah North.

METHODS

The state health clinics' records for patient visits related to asthma were collected for the timeframe spanning 2014 to 2022. Exposure was defined as the distance from the SIP, Majan Industerial Area (MIA), and Sohar Industerial Zone (SIZ) to determine high-, intermediate-, and low-exposure zones (<6 km, 6-12 km and >12 km, respectively). Exposure effect modifications by age, gender, and smoking status were also examined.

RESULTS

The conducted cross-sectional study of 410 patients (46.1% males and 53.9% females) living in over 17 areas around SIP revealed that 73.2% of asthmatics were under 50 years old, with severity significantly associated with closeness to the port. Risk ratios were estimated to be (RR:2.42; CI95%: 1.01-5.78), (RR:1.91; CI95%: 1.01-3.6), and (RR:1.68; CI95%: 0.92-3.09) for SIP, MIP, and SIZ areas, respectively, compared to the control area. Falaj Al Qabail (6.4 km) and Majees (6 km) had the highest number of asthma patients (N 69 and N 72) and highest percentages of severe asthma cases among these patients (28% and 24%) with significant risk ratios (RR:2.97; CI95%: 1.19-7.45 and RR:2.55; CI95%: 1.00-6.48), correspondingly. Moreover, severe asthma prevalence peaked in the 25-50 age group (RR:2.05; CI95%: 1.26-3.33), and this linkage between asthma and age was much more pronounced in males than females. Smoking and exposure to certain contaminants (dust and smoke) also increased the risk of severe asthma symptoms, but their effects were less important in the high-risk zone, suggesting much more important risk factors. A neural network model accurately predicted asthma risk (94.8% accuracy), with proximity to SIP as the most influential predictor.

CONCLUSIONS

This study highlights the high asthma burden near SIP, linked to port proximity, smoking, and wind direction as major risk factors. These findings inform vital public health policies to reduce air pollution and improve respiratory health in the region, prompting national policy review.

Associations of long-term exposure to air pollution with prevalence of pulmonary nodules: A cross-sectional study in Shijiazhuang, China

A complete understanding of the associations of ambient air pollution with prevalence of pulmonary nodule is lacking. We aimed to investigate the associations of ambient air pollutants with prevalence of pulmonary nodule. A total of 9991 health examination participants was enrolled and 3166 was elected in the final in Shijiazhuang between April 1st, 2018, and December 31st, 2018. 107 participants were diagnosed in pulmonary nodule while 3059 participants were diagnosed in non-pulmonary (named control). The individual exposure of participants was evaluation by Empirical Bayesian Kriging model according to their residential or work addresses. The pulmonary nodules were found and diagnosed by health examination through chest x-ray detection. Our results suggested that there were positive associations between prevalence of pulmonary nodules and PM2.5 (OR = 1.06, 95% CI: 1.02, 1.11) as well as O3 (OR = 1.49, 95% CI: 1.35, 1.66) levels. The platelet count (PLT) acted as the mediator of pulmonary nodules related with the PM2.5 exposure, while the neutrophil-to-lymphocyte ratio (NLR) as well as platelet-to-lymphocyte ratio (PLR) were the mediators of pulmonary nodules related with the O3 exposure. This study suggests that long-term exposure to PM2.5 and O3 may significantly associated with prevalence of pulmonary nodules, and the above associations are mediated by PLT, NLR and PLR.

Do sex and gender modify the association between green space and physical health? A systematic review

A growing literature shows that green space can have protective effects on human health. As a marginalized group, women often have worse life outcomes than men, including disparities in some health outcomes. Given their marginalization, women might have "more to gain" than men from living near green spaces. Yet, limited research has deliberately studied whether green space-health associations are stronger for women or men. We conducted a systematic review to synthesize empirical evidence on whether sex or gender modifies the protective associations between green space and seven physical health outcomes (cardiovascular disease, cancer, diabetes, general physical health, non-malignant respiratory disease, mortality, and obesity-related health outcomes). After searching five databases, we identified 62 articles (including 81 relevant analyses) examining whether such effect modification existed. We classified analyses based on whether green space-health were stronger for women, no sex/gender differences were detected, or such associations were stronger for men. Most analyses found that green space-physical health associations were stronger for women than for men when considering study results across all selected health outcomes. Also, women showed stronger protective associations with green space than men for obesity-related outcomes and mortality. Additionally, the protective green space-health associations were slightly stronger among women for green land cover (greenness, NDVI) than for public green space (parks), and women were also favored over men when green space was measured very close to one's home (0-500 m). Further, the green space-health associations were stronger for women than for men in Europe and North America, but not in other continents. As many government agencies and nongovernmental organizations worldwide work to advance gender equity, our review shows that green space could help reduce some gender-based health disparities. More robust empirical studies (e.g., experimental) are needed to contribute to this body of evidence.

Effect of ambient air pollution exposure on renal dysfunction among hospitalized patients in Shanghai, China

OBJECTIVES

We investigated whether long-term ambient air pollutants (AAP) exposure was associated with estimated glomerular filtration rate (eGFR) among hospitalized patients living in urban areas of Shanghai, China.

STUDY DESIGN

This was a cross-sectional observational study.

METHODS

A total of 3622 newly hospitalized inpatients were investigated from October 2014 to May 2015. The prior year's average exposure to particulate matter (PM) of each participant was estimated using the Kriging interpolation method of ArcGIS. The estimated eGFR was calculated according to the chronic kidney disease epidemiology collaboration (CKD-EPI) equation. Both generalized linear and logistic regression models were applied to assess the associations between AAP and renal function.

RESULTS

One-year PM₁₀ exposure was associated with lower eGFR; each standard deviation (SD) increase in PM₁₀ was significantly associated with the increased prevalence of CKD [adjusted odds ratio (OR) 1.11; 95% confidence interval (CI): 1.02, 1.21], and lower eGFR by -0.40 (95%CI: -0.80, -0.01) ml/min/1.73 m². Moreover, the effect of PM₁₀ was significantly greater in people over 65 years old.

CONCLUSION

Our results supported that exposure to ambient PM₁₀ increased the risk of CKD and negatively affected renal function among Chinese adults.

Overweight modifies the association between long-term ambient air pollution and prehypertension in Chinese adults: the 33 Communities Chinese Health Study

BACKGROUND

Research regarding the interaction of ambient air pollution and overweight on prehypertension is scarce. We aimed to test whether overweight modifies the association between long-term exposure to ambient air pollution and prehypertension in Chinese adults.

METHODS

A total of 16,188 Chinese adults, aged 18-74 years old, from 33 communities in 3 Northeastern Chinese cities were evaluated. Three-year average levels of particles with an aerodynamic diameter ≤ 10 μm (PM₁₀), sulfur dioxides (SO₂), nitrogen dioxides (NO₂), and ozone (O₃) were calculated at monitoring stations. Generalized additive models and 2-level regression analyses were applied.

RESULTS

We observed significant interactions between air pollutants and overweight on prehypertension and blood pressure. The associations of PM₁₀, SO₂, NO₂, and O₃ with prehypertension were significant among overweight participants (Prevalence Rate Ratios (PRRs) per interquartile range (IQR) of air pollutants: 1.14-1.20), but not among normal weight participants (PRRs: 0.98-1.04). PM₁₀, SO₂, and O₃ were significantly associated with systolic blood pressure (SBP), and the magnitudes of these associations were higher among overweight adults (increases in SBP per IQR of air pollutants: 1.82-4.53 mmHg) than those among normal weight adults (increases in SBP: 0.42-0.61 mmHg). For diastolic blood pressure (DBP), significant associations were mainly observed in overweight participants (increases in DBP: 0.80-1.63 mmHg). Further stratified analyses showed that all these interactions were stronger in women, the older, and participants living in areas with lower income levels or higher population density.

CONCLUSIONS

Being overweight may enhance the effects of ambient air pollution on prehypertension and blood pressure in Chinese adults.

Epidemiological study of PM2.5 and risk of COPD-related hospital visits in association with particle constituents in Chuncheon, Korea

Background and objective

Aside from smoking, which is already recognized as a strong risk factor for COPD, interest in the impact of particulate matter (PM) on COPD is increasing. This study aimed to investigate the effect of PM, especially with an aerodynamic diameter ≤2.5 µm (PM2.5), and its chemical constituents on the exacerbation of COPD.

Methods

Data on hospital visits including admission and outpatient clinic visits for exacerbation of COPD in Chuncheon, Korea, between 2006 and 2012 were extracted from the National Health Insurance Service database. PM2.5 and its chemical constituents were measured on the roof of the four-story Kangwon National University Natural Sciences building once every 3 days. Meteorological data were provided by the Korean Meteorological Administration.

Results

During the study period, the mean level of PM2.5 was 35.0±25.2 µg/m3, and the number of daily hospital visits were 6.42±4.28 and 2.07±1.93 for males and females, respectively. The number of COPD-related hospital visits increased with increasing PM2.5 after adjusting for meteorological covariates and females tended to be more affected sooner than males. Among the PM2.5 constituents, Al, Si, and elemental carbon were associated with increased hospital visits and there was a difference according to sex. In males, some constituents of PM2.5 were related to an increased risk of a hospital visit, mainly on the first and second days of measurement (Lag1 and Lag2). In contrast, there was no significant increase in the risk of hospital visits due to any of the PM2.5 constituents in females.

Conclusion

Concentrations of PM2.5 mass and some of the PM2.5 constituents were associated with increased COPD-related hospital visits in Chuncheon.

Is prehypertension more strongly associated with long-term ambient air pollution exposure than hypertension? Findings from the 33 Communities Chinese Health Study

Numerous studies have evaluated the effects of long-term exposure to ambient air pollution on hypertension. However, little information exists regarding its effects on prehypertension, a very common, but understudied cardiovascular indicator. We evaluated data from 24,845 adults (ages 18-74 years) living in three Northeastern Chinese cities in 2009. Blood pressure (BP) was measured by trained observers using a standardized mercuric-column sphygmomanometer. Three-year (from 2006 to 2008) average concentrations of particles with an aerodynamic diameter ≤10 μm (PM₁₀), sulfur dioxide (SO₂), nitrogen dioxides (NO₂), and ozone (O₃) were calculated using data from monitoring stations. Effects were analyzed using generalized additive models and two-level regression analyses, controlling for covariates. We found positive associations of all pollutants with prehypertension (e.g. odds ratio (OR) was 1.17 (95% confidence interval (CI), 1.09-1.25) per interquartile range (IQR) of PM₁₀) in a fully adjusted model, as compared to normotensive participants. These associations were stronger than associations with hypertension (e.g. OR was 1.03 (95% CI, 1.00, 1.07) per IQR of PM₁₀). We have also found positive associations of all studied pollutants with systolic and diastolic BP: e.g., associations with PM₁₀ per IQR were 1.24 mmHg (95% CI, 1.03-1.45) for systolic BP and 0.47 mmHg (95% CI, 0.33-0.61) for diastolic BP. Further, we observed that associations with BP were stronger in women and in older participants (systolic BP only). In conclusion, long-term exposure to ambient air pollution was more strongly associated with prehypertension than with hypertension, especially among females and the elderly. Thus, interventions to reduce air pollution are of great significance for preventing future cardiovascular events, particularly among individuals with prehypertension.

Ambient air pollution and years of life lost in Ningbo, China

To evaluate the burden of air pollution on years of life lost (YLL) in addition to mortality, we conducted a time series analysis based on the data on air pollution, meteorological conditions and 163,704 non-accidental deaths of Ningbo, China, 2009–2013. The mean concentrations of particulate matter with aerodynamic diameter <10 μm, particulate matter with aerodynamic diameter <2.5 μm, sulfur dioxide and nitrogen dioxide were 84.0 μg/m³, 60.1 μg/m³, 25.1 μg/m³ and 41.7 μg/m³, respectively. An increase of 10-μg/m³ in particulate matter with aerodynamic diameter <10 μm, particulate matter with aerodynamic diameter <2.5 μm, sulfur dioxide and nitrogen dioxide was associated with 4.27 (95% confidence interval [CI] 1.17–7.38), 2.97 (95% CI −2.01–7.95), 29.98 (95% CI 19.21–40.76) and 16.58 (95% CI 8.19–24.97) YLL, respectively, and 0.53% (95% CI 0.29–0.76%), 0.57% (95% CI 0.20–0.95%), 2.89% (95% CI 2.04–3.76%), and 1.65% (95% CI 1.01–2.30%) increase of daily death counts, respectively. The impact of air pollution lasted for four days (lag 0–3), and were more significant in the elderly than in the young population for both outcomes. These findings clarify the burden of air pollution on YLL and highlight the importance and urgency of air pollution control in China.

Can the Air Pollution Index be used to communicate the health risks of air pollution?

The validity of using the Air Pollution Index (API) to assess health impacts of air pollution and potential modification by individual characteristics on air pollution effects remain uncertain. We applied distributed lag non-linear models (DLNMs) to assess associations of daily API, specific pollution indices for PM10, SO2, NO2 and the weighted combined API (APIw) with mortality during 2003-2011 in Guangzhou, China. An increase of 10 in API was associated with a 0.88% (95% confidence interval (CI): 0.50, 1.27%) increase of non-accidental mortality at lag 0-2 days. Harvesting effects appeared after 2 days' exposure. The effect estimate of API over lag 0-15 days was statistically significant and similar with those of pollutant-specific indices and APIw. Stronger associations between API and mortality were observed in the elderly, females and residents with low educational attainment. In conclusion, the API can be used to communicate health risks of air pollution.

Gender-specific differences of interaction between obesity and air pollution on stroke and cardiovascular diseases in Chinese adults from a high pollution range area: A large population based cross sectional study

BACKGROUND

Little information exists regarding the interaction effects of obesity with long-term air pollution exposure on cardiovascular diseases (CVDs) and stroke in areas of high pollution. The aim of the present study is to examine whether obesity modifies CVD-related associations among people living in an industrial province of northeast China.

METHODS

We studied 24,845 Chinese adults, aged 18 to 74 years old, from three Northeastern Chinese cities in 2009 utilizing a cross-sectional study design. Body weight and height were measured by trained observers. Overweight and obesity were defined as a body mass index (BMI) between 25-29.9 and ≥30 kg/m(2), respectively. Prevalence rate and related risk factors of cardiovascular and cerebrovascular diseases were investigated by a questionnaire. Three-year (2006-2008) average concentrations of particulate matter (PM10), sulfur dioxide (SO2), nitrogen dioxides (NO2), and ozone (O3) were measured by fixed monitoring stations. All the participants lived within 1 km of air monitoring sites. Two-level logistic regression (personal level and district-specific pollutant level) was used to examine these effects, controlling for covariates.

RESULTS

We observed significant interactions between exposure and obesity on CVDs and stroke. The associations between annual pollutant concentrations and CVDs and stroke were strongest in obese subjects (OR 1.15-1.47 for stroke, 1.33-1.59 for CVDs), less strong in overweight subjects (OR 1.22-1.35 for stroke, 1.07-1.13 for CVDs), and weakest in normal weight subjects (OR ranged from 0.98-1.01 for stroke, 0.93-1.15 for CVDs). When stratified by gender, these interactions were significant only in women.

CONCLUSIONS

Study findings indicate that being overweight and obese may enhance the effects of air pollution on the prevalence of CVDs and stroke in Northeastern metropolitan China. Further studies will be needed to investigate the temporality of BMI relative to exposure and onset of disease.

Gender-specific differences in associations of overweight and obesity with asthma and asthma-related symptoms in 30 056 children: result from 25 districts of Northeastern China

OBJECTIVE

The relationship between obesity and allergic respiratory diseases in childhood is still controversial. Furthermore, significant debate on the issue of whether or not gender modifies this association also exists due to inconsistent findings. The objective of this study is to evaluate the association between obesity and respiratory health in children, and to investigate the modifications of gender on this association.

METHODS

30 056 children (aged 2-14 years) were randomly selected from 25 districts within 7 cities in Northeastern China in 2009. A standard questionnaire from the American Thoracic Society was used to characterize the children's histories of respiratory symptoms and illnesses. Child weight and height were measured, and obesity was calculated with an age and sex-specific body mass index.

RESULTS

The overall prevalence rates of obesity and overweightness were 14.08% and 12.32%, respectively. Compared to the children with normal body weights, asthma and asthma-related symptoms were more prevalent in overweight and obese children. Analysis stratified by gender showed that obesity was associated with more respiratory symptoms and diseases in females than in males. A significant association between obesity and diagnosed asthma [adjusted odds ratio (aOR) = 1.28; 95% confidence interval (CI): 1.02-1.60], as well as current wheezing (aOR = 1.46; 95%CI: 1.20-1.79) was found in females but not in males.

CONCLUSIONS

There is an association between asthma symptoms and obesity in these Chinese children, and obesity had a significantly larger effect on females than males.

Allergic predisposition modifies the effects of pet exposure on respiratory disease in boys and girls: the seven northeast cities of China (SNECC) study

BACKGROUND

The relationship between pet exposure and the respiratory disease in childhood has been a controversial topic, much is still unknown about the nature of the associations between pet exposure and children's respiratory health stratified by gender and allergic predisposition. The objective of the present study was to assess the relationship between pet exposure and respiratory symptoms in Chinese children, and to investigate the modified effects of gender and allergic predisposition on such relationship.

METHODS

31,049 children were selected from 25 districts of 7 cities in Northeast China in 2009. Information on respiratory health and exposure to home environmental factors was obtained via a standard questionnaire designed by the American Thoracic Society.

RESULTS

Children with an allergic predisposition were found to have more frequent exposure to pets than those without an allergic predisposition (18.5% vs. 15.4%). In children without an allergic predisposition, pet exposure was associated with increased susceptibility to respiratory symptoms/diseases, with girls being more susceptible than boys. No association was found between pet exposure and respiratory symptoms/diseases in boys with an allergic predisposition. In girls with an allergic predisposition, association was found between doctor-diagnosed asthma and pet exposure of their mother during pregnancy (adjusted odds ratio (ORs)=2.03; 95% confidence interval (CI): 1.01-4.33), and their current pet exposure (ORs=1.37; 95%CI: 1.00-1.88).

CONCLUSIONS

Pet exposure in children without an allergic predisposition was associated with increased susceptibility to respiratory disease, with girls being more susceptible than boys.

Susceptibility to air pollution effects on mortality in Seoul, Korea: a case-crossover analysis of individual-level effect modifiers

Air pollution's mortality effects may differ by subpopulation; however, few studies have investigated this issue in Asia. We investigated susceptibility to air pollutants on total, cardiovascular, and respiratory mortality in Seoul, Korea for the period 2000-2007. We applied time-stratified case-crossover analysis, which allows direct modeling of interaction terms, to estimate susceptibility based on sex, age, education, marital status, and occupation. An interquartile range increase in pollution was associated with odds ratios of 0.94 (95% confidence interval, 0.25-1.62), 2.27 (1.03-3.53), 1.94 (0.80-3.09), and 2.21 (1.00-3.43) for total mortality and 1.95 (0.64-3.27), 4.82 (2.18-7.54), 3.64 (1.46-5.87), and 4.32 (1.77-6.92) for cardiovascular mortality for PM(10), nitrogen dioxide (NO(2)), sulfur dioxide (SO(2)), and carbon monoxide (CO), respectively. Ozone effect estimates were positive, but not statistically significant. Results indicate that some populations are more susceptible than others. For total or cardiovascular mortality, associations were higher for males, those 65-74 years, and those with no education or manual occupation for some pollutants. For example, the odds ratio for SO(2) and cardiovascular mortality was 1.19 (1.03-1.37) times higher for those with manual occupations than professional occupations. Our findings provide evidence that some populations are more susceptible to the effects of air pollution than others, which has implications for public policy and risk assessment for susceptible subpopulations.

Long-term exposure to ambient air pollution and mortality due to cardiovascular disease and cerebrovascular disease in Shenyang, China

Background

The relationship between ambient air pollution exposure and mortality of cardiovascular and cerebrovascular diseases in human is controversial, and there is little information about how exposures to ambient air pollution contribution to the mortality of cardiovascular and cerebrovascular diseases among Chinese. The aim of the present study was to examine whether exposure to ambient-air pollution increases the risk for cardiovascular and cerebrovascular disease.

Methodology/Principal Findings

We conducted a retrospective cohort study among humans to examine the association between compound-air pollutants [particulate matter <10 µm in aerodynamic diameter (PM₁₀), sulfur dioxide (SO₂) and nitrogen dioxide (NO₂)] and mortality in Shenyang, China, using 12 years of data (1998–2009). Also, stratified analysis by sex, age, education, and income was conducted for cardiovascular and cerebrovascular mortality. The results showed that an increase of 10 µg/m³ in a year average concentration of PM₁₀ corresponds to 55% increase in the risk of a death cardiovascular disease (hazard ratio [HR], 1.55; 95% confidence interval [CI], 1.51 to 1.60) and 49% increase in cerebrovascular disease (HR, 1.49; 95% CI, 1.45 to 1.53), respectively. The corresponding figures of adjusted HR (95%CI) for a 10 µg/m³ increase in NO₂ was 2.46 (2.31 to 2.63) for cardiovascular mortality and 2.44 (2.27 to 2.62) for cerebrovascular mortality, respectively. The effects of air pollution were more evident in female that in male, and nonsmokers and residents with BMI<18.5 were more vulnerable to outdoor air pollution.

Conclusion/Significance

Long-term exposure to ambient air pollution is associated with the death of cardiovascular and cerebrovascular diseases among Chinese populations.

A growing role for gender analysis in air pollution epidemiology

Epidemiologic studies of air pollution effects on respiratory health report significant modification by sex, although results are not uniform. Importantly, it remains unclear whether modifications are attributable to socially derived gendered exposures, to sex-linked physiological differences, or to some interplay thereof. Gender analysis, which aims to disaggregate social from biological differences between males and females, may help to elucidate these possible sources of effect modification. Studies of children suggest stronger effects among boys in early life and among girls in later childhood. The qualitative review describes possible sources of difference in air pollution response between women and men, which may vary by life stage, coexposures, hormonal status, or other factors. The sources of observed effect modifications remain unclear, although gender analytic approaches may help to disentangle gender and sex differences in pollution response. A framework for incorporating gender analysis into environmental epidemiology is offered, along with several potentially useful methods from gender analysis.

A framework for examining social stress and susceptibility to air pollution in respiratory health

There is growing interest in disentangling the health effects of spatially clustered social and physical environmental exposures and in exploring potential synergies among them, with particular attention directed to the combined effects of psychosocial stress and air pollution. Both exposures may be elevated in lower-income urban communities, and it has been hypothesized that stress, which can influence immune function and susceptibility, may potentiate the effects of air pollution in respiratory disease onset and exacerbation. In this paper, we review the existing epidemiologic and toxicologic evidence on synergistic effects of stress and pollution, and describe the physiologic effects of stress and key issues related to measuring and evaluating stress as it relates to physical environmental exposures and susceptibility. Finally, we identify some of the major methodologic challenges ahead as we work toward disentangling the health effects of clustered social and physical exposures and accurately describing the interplay among these exposures. As this research proceeds, we recommend careful attention to the relative temporalities of stress and pollution exposures, to nonlinearities in their independent and combined effects, to physiologic pathways not elucidated by epidemiologic methods, and to the relative spatial distributions of social and physical exposures at multiple geographic scales.

A growing role for gender analysis in air pollution epidemiology

OBJECTIVE

Epidemiologic studies of air pollution effects on respiratory health report significant modification by sex, although results are not uniform. Importantly, it remains unclear whether modifications are attributable to socially derived gendered exposures, to sex-linked physiological differences, or to some interplay thereof. Gender analysis, which aims to disaggregate social from biological differences between males and females, may help to elucidate these possible sources of effect modification.

DATA SOURCES AND DATA EXTRACTION

A PubMed literature search was performed in July 2009, using the terms "respiratory" and any of "sex" or "gender" or "men and women" or "boys and girls" and either "PM2.5" (particulate matter <or= 2.5 microm in aerodynamic diameter) or "NO2" (nitrogen dioxide). I reviewed the identified studies, and others cited therein, to summarize current evidence of effect modification, with attention to authors' interpretation of observed differences. Owing to broad differences in exposure mixes, outcomes, and analytic techniques, with few studies examining any given combination thereof, meta-analysis was not deemed appropriate at this time.

DATA SYNTHESIS

More studies of adults report stronger effects among women, particularly for older persons or where using residential exposure assessment. Studies of children suggest stronger effects among boys in early life and among girls in later childhood.

CONCLUSIONS

The qualitative review describes possible sources of difference in air pollution response between women and men, which may vary by life stage, coexposures, hormonal status, or other factors. The sources of observed effect modifications remain unclear, although gender analytic approaches may help to disentangle gender and sex differences in pollution response. A framework for incorporating gender analysis into environmental epidemiology is offered, along with several potentially useful methods from gender analysis.

A framework for examining social stress and susceptibility to air pollution in respiratory health

OBJECTIVE

There is growing interest in disentangling the health effects of spatially clustered social and physical environmental exposures and in exploring potential synergies among them, with particular attention directed to the combined effects of psychosocial stress and air pollution. Both exposures may be elevated in lower-income urban communities, and it has been hypothesized that stress, which can influence immune function and susceptibility, may potentiate the effects of air pollution in respiratory disease onset and exacerbation. In this paper, we attempt to synthesize the relevant research from social and environmental epidemiology, toxicology, immunology, and exposure assessment to provide a useful framework for environmental health researchers aiming to investigate the health effects of environmental pollution in combination with social or psychological factors.

DATA SYNTHESIS

We review the existing epidemiologic and toxicologic evidence on synergistic effects of stress and pollution, and then describe the physiologic effects of stress and key issues related to measuring and evaluating stress as it relates to physical environmental exposures and susceptibility. Finally, we identify some of the major methodologic challenges ahead as we work toward disentangling the health effects of clustered social and physical exposures and accurately describing the interplay among these exposures.

CONCLUSIONS

There is still tremendous work to be done toward understanding the combined and potentially synergistic health effects of stress and pollution. As this research proceeds, we recommend careful attention to the relative temporalities of stress and pollution exposures, to nonlinearities in their independent and combined effects, to physiologic pathways not elucidated by epidemiologic methods, and to the relative spatial distributions of social and physical exposures at multiple geographic scales.

Real-time measurement of particulate matter deposition in the lung

Air pollution and cigarette smoke are recognized health risks. A method was developed for the measurement of the deposition fraction (DF) of polydisperse particulate matter (PM) in human airways. Ten normal volunteers [three females, age range 18-67 years, mean age (SD) 43.9 (14)] made single breath exhalations after inhalation to total lung capacity. The exhaled breath was diverted to a multichannel laser diffraction chamber where the particulate profiler measured 0.3 - 1.0-microm particles. DF was inversely related to expiration flow-rate, 0.69 (0.02) at 4 l min-1 and 0.5 (0.01) at 13 l min-1, respectively (p<0.05), and was influenced by the inhalation flow-rate [0.70 (0.02) at 3 l min-1 and 0.59 (0.02) at 13 l min-1, respectively (p<0.05)], while no differences were found between nasal and oral inhalation (0.68 (0.05) versus 0.67 (0.06), p>0.05). Higher breath holding times were associated with elevated DF [0.74 (0.02) at 20 s, and 0.62 (0.05) without breath holding (p<0.01)]. When the expiratory flow was controlled and the breath hold time standardized, DF was reproducible (CV = 4.85%). PM can be measured in the exhaled breath and its DF can be quantified using a portable device. These methods may be useful in studies investigating the health effects of air pollution and tobacco smoke.

Season, sex, age, and education as modifiers of the effects of outdoor air pollution on daily mortality in Shanghai, China: The Public Health and Air Pollution in Asia (PAPA) Study

BACKGROUND

Various factors can modify the health effects of outdoor air pollution. Prior findings about modifiers are inconsistent, and most of these studies were conducted in developed countries.

OBJECTIVES

We conducted a time-series analysis to examine the modifying effect of season, sex, age, and education on the association between outdoor air pollutants [particulate matter < 10 microm in aerodynamic diameter (PM(10)), sulfur dioxide, nitrogen dioxide, and ozone] and daily mortality in Shanghai, China, using 4 years of daily data (2001-2004).

METHODS

Using a natural spline model to analyze the data, we examined effects of air pollution for the warm season (April-September) and cool season (October-March) separately. For total mortality, we examined the association stratified by sex and age. Stratified analysis by educational attainment was conducted for total, cardiovascular, and respiratory mortality.

RESULTS

Outdoor air pollution was associated with mortality from all causes and from cardiorespiratory diseases in Shanghai. An increase of 10 mug/m(3) in a 2-day average concentration of PM(10), SO(2), NO(2), and O(3) corresponds to increases in all-cause mortality of 0.25% [95% confidence interval (CI), 0.14-0.37), 0.95% (95% CI, 0.62-1.28), 0.97% (95% CI, 0.66-1.27), and 0.31% (95% CI, 0.04-0.58), respectively. The effects of air pollutants were more evident in the cool season than in the warm season, and females and the elderly were more vulnerable to outdoor air pollution. Effects of air pollution were generally greater in residents with low educational attainment (illiterate or primary school) compared with those with high educational attainment (middle school or above).

CONCLUSIONS

Season, sex, age, and education may modify the health effects of outdoor air pollution in Shanghai. These findings provide new information about the effects of modifiers on the relationship between daily mortality and air pollution in developing countries and may have implications for local environmental and social policies.

[Monte-Carlo-Model for the aerosol bolus dispersion in the human lung--part 1: theoretical model description and application]

Aerosol bolus dispersion, which has excited enormous interest in lung medicine due to its possible use as an efficient toolfor the non-invasive clinical diagnosis of lung function, was simulated by a Monte Carlo model based on the concept of effective diffusivities and a stochastic lung geometry. The mathematical approach enabled the computation of essential characteristics of the exhaled bolus (half width, standard deviation, skewness, and mode shift) as well as the estimation of their dependence upon the volumetric lung depth (VLD) of the inhaled bolus. Results of the dispersion model generally show a very good correspondence with preliminary published experimental data. Half width and standard deviation of the exhaled bolus increase with VLD according to specific functions, whereas skewness and mode shift are subject to a decrease. While no correlation between bolus dispersion and flow rate could be worked out with the model, dispersion linearly increased with total lung capacity (TLC).

Traffic and outdoor air pollution levels near residences and poorly controlled asthma in adults

BACKGROUND

Air pollution may exacerbate asthma.

OBJECTIVE

To investigate associations between traffic and outdoor air pollution levels near residences and poorly controlled asthma among adults diagnosed as having asthma in Los Angeles and San Diego counties, California.

METHODS

We estimated traffic density within 500 ft of 2001 California Health Interview Survey respondents' reported residential cross-street intersections. Additionally, we assigned annual average concentrations of ozone, nitrogen dioxide, particulate matter 2.5 and 10 micrometers or less in diameter, and carbon monoxide measured at government monitoring stations within a 5-mile radius of the reported residential cross-street intersections.

RESULTS

We observed a 2-fold increase in poorly controlled asthma (odds ratio [OR], 2.11; 95% confidence interval [CI], 1.38-3.23) among asthmatic adults in the highest quintile of traffic density after adjusting for age, sex, race, and poverty. Similar increases were seen for nonelderly adults, men, and women, although associations seemed strongest in elderly adults (OR, 3.00; 95% CI, 1.13-7.91). Ozone exposures were associated with poorly controlled asthma among elderly adults (OR, 1.70; 95% CI, 0.91-3.18 per 1 pphm) and men (OR, 1.76; 95% CI, 1.05-2.94 per 1 pphm), whereas particulate matter 10 micrometers or less seemed to affect primarily women (OR, 2.06; 95% CI, 1.17-3.61), even at levels below the national air quality standard.

CONCLUSIONS

Heavy traffic and high air pollution levels near residences are associated with poorly controlled asthma.

The growing burden of chronic obstructive pulmonary disease and lung cancer in women: examining sex differences in cigarette smoke metabolism

Smoking-related lung diseases such as chronic obstructive pulmonary disease (COPD) and lung cancer are growing epidemics in women in the United States and elsewhere. Although some of this disturbing trend in women can be attributed to changing smoking habits, there is emerging evidence that women may be biologically more susceptible to the harmful effects of cigarette smoke than are men. Estrogen and related compounds may up-regulate the expression of cytochrome P450 (CYP) enzymes in lungs and liver, which are involved in the metabolism of various constituents of cigarette smoke. Although metabolism of foreign substances is usually beneficial in eliminating potential toxins from the body, in some instances the metabolic process can transform harmless substances into toxic chemicals through a process called metabolic bioactivation. One important xenobiotic substrate for CYP enzymes in cigarette smoke is polycyclic aromatic hydrocarbon, which in its native form is relatively harmless in small doses but upon bioactivation by CYP enzymes, can become very toxic substances for the lungs. In this article, we explore CYP and other related pathways as potential mechanisms and targets of future research and novel discoveries to curb the growing epidemic of COPD and lung cancer in women.

Glutathione S-transferase genotypes modify lung function decline in the general population: SAPALDIA cohort study

Background

Understanding the environmental and genetic risk factors of accelerated lung function decline in the general population is a first step in a prevention strategy against the worldwide increasing respiratory pathology of chronic obstructive pulmonary disease (COPD). Deficiency in antioxidative and detoxifying Glutathione S-transferase (GST) gene has been associated with poorer lung function in children, smokers and patients with respiratory diseases. In the present study, we assessed whether low activity variants in GST genes are also associated with accelerated lung function decline in the general adult population.

Methods

We examined with multiple regression analysis the association of polymorphisms in GSTM1, GSTT1 and GSTP1 genes with annual decline in FEV1, FVC, and FEF_25–75 during 11 years of follow-up in 4686 subjects of the prospective SAPALDIA cohort representative of the Swiss general population. Effect modification by smoking, gender, bronchial hyperresponisveness and age was studied.

Results

The associations of GST genotypes with FEV1, FVC, and FEF_25–75 were comparable in direction, but most consistent for FEV1. GSTT1 homozygous gene deletion alone or in combination with GSTM1 homozygous gene deletion was associated with excess decline in FEV1 in men, but not women, irrespective of smoking status. The additional mean annual decline in FEV1 in men with GSTT1 and concurrent GSTM1 gene deletion was -8.3 ml/yr (95% confidence interval: -12.6 to -3.9) relative to men without these gene deletions. The GSTT1 effect on the FEV1 decline comparable to the observed difference in FEV1 decline between never and persistent smoking men. Effect modification by gender was statistically significant.

Conclusion

Our results suggest that genetic GSTT1 deficiency is a prevalent and strong determinant of accelerated lung function decline in the male general population.

Clinical perspectives on pulmonary systemic and macromolecular delivery

The large epithelial surface area, the high organ vascularization, the thin nature of the alveolar epithelium and the immense capacity for solute exchange are factors that led the lung to serve as an ideal administration route for the application of drugs for treatment of systemic disorders. However, the deposition behaviour of aerosol particles in the respiratory tract depends on a number of physical (e.g. properties of the particle), chemical (e.g. properties of the drug) and physiological (e.g. breathing pattern, pulmonary diseases) factors. If these are not considered, it will not be possible to deposit a reproducible and sufficient amount of drug in a predefined lung region by means of aerosol inhalation. The lack of consideration of such issues led to many problems in inhalation drug therapy for many years mainly because physiological background of aerosol inhalation was not fully understood. However, over the last 20 years, there has been considerable progress in aerosol research and in the understanding of the underlying mechanisms of particle inhalation and pulmonary particle deposition. As a consequence, an increasing number of studies have been performed for the lung administration of drugs using a variety of different inhalation techniques. This review describes the physical and in part some of the physiological requirements that need to be considered for the optimization of pulmonary drug delivery to target certain lung regions.

Bronchial hyperresponsiveness and the development of asthma and COPD in asymptomatic individuals: SAPALDIA cohort study

BACKGROUND

Bronchial hyperresponsiveness (BHR) is a common feature of asthma. However, BHR is also present in asymptomatic individuals and its clinical and prognostic significance is unclear. We hypothesised that BHR might play a role in the development of chronic obstructive pulmonary disease (COPD) as well as asthma.

METHODS

In 1991 respiratory symptoms and BHR to methacholine were evaluated in 7126 of the 9651 participants in the SAPALDIA cohort study. Eleven years later 5825 of these participants were re-evaluated, of whom 4852 performed spirometric tests. COPD was defined as an FEV1/FVC ratio of <0.70.

RESULTS

In 1991 17% of participants had BHR, of whom 51% were asymptomatic. Eleven years later the prevalence of asthma, wheeze, and shortness of breath in formerly asymptomatic subjects with or without BHR was, respectively, 5.7% v 2.0%, 8.3% v 3.4%, and 19.1% v 11.9% (all p<0.001). Similar differences were observed for chronic cough (5.9% v 2.3%; p = 0.002) and COPD (37.9% v 14.3%; p<0.001). BHR conferred an adjusted odds ratio (OR) of 2.9 (95% CI 1.8 to 4.5) for wheezing at follow up among asymptomatic participants. The adjusted OR for COPD was 4.5 (95% CI 3.3 to 6.0). Silent BHR was associated with a significantly accelerated decline in FEV1 by 12 (5-18), 11 (5-16), and 4 (2-8) ml/year in current smokers, former smokers and never smokers, respectively, at SAPALDIA 2.

CONCLUSIONS

BHR is a risk factor for an accelerated decline in FEV1 and the development of asthma and COPD, irrespective of atopic status. Current smokers with BHR have a particularly high loss of FEV1.

Individual-level modifiers of the effects of particulate matter on daily mortality

Consistent evidence has shown a positive association between particulate matter with an aerodiameter of less than or equal to 10 mum (PM(10)) and daily mortality. Less is known about the modification of this association by factors measured at the individual level. The authors examined this question in a case-crossover study of 20 US cities. Mortality events (1.9 million) were obtained for nonaccidental, respiratory, heart disease, and stroke mortality between 1989 and 2000. PM(10) concentrations were obtained from the US Environmental Protection Agency. The authors examined the modification of the PM(10)-mortality association by sociodemographics, location of death, season, and secondary diagnoses. They found different patterns of PM(10)-mortality associations by gender and age but no differences by race. The level of education was inversely related to the risk of mortality associated with PM(10). PM(10)-related, out-of-hospital deaths were more likely than were in-hospital deaths, as were those occurring during spring/fall versus summer/winter. A secondary diagnosis of diabetes modified the effect of PM(10) for respiratory and stroke mortality. Pneumonia was a positive effect modifier for deaths from all causes and stroke, while secondary stroke modified the effects for all-cause and respiratory deaths. The findings suggest that more attention must be paid to population characteristics to identify greater likelihood of exposures and susceptibility and, as a result, to improve policy making for air pollution standards.

Association of ambient air pollution with respiratory hospitalization in a government-designated "area of concern": the case of Windsor, Ontario

This study is part of a larger research program to examine the relationship between ambient air quality and health in Windsor, Ontario, Canada. We assessed the association between air pollution and daily respiratory hospitalization for different age and sex groups from 1995 to 2000. The pollutants included were nitrogen dioxide, sulfur dioxide, carbon monoxide, ozone, particulate matter 10 microm in diameter (PM10), coefficient of haze (COH), and total reduced sulfur (TRS). We calculated relative risk (RR) estimates using both time-series and case-crossover methods after controlling for appropriate confounders (temperature, humidity, and change in barometric pressure). The results of both analyses were consistent. We found associations between NO2, SO2, CO, COH, or PM10 and daily hospital admission of respiratory diseases especially among females. For females 0-14 years of age, there was 1-day delayed effect of NO2 (RR = 1.19, case-crossover method), a current-day SO2 (RR = 1.11, time series), and current-day and 1- and 2-day delayed effects for CO by case crossover (RR = 1.15, 1.19, 1.22, respectively). Time-series analysis showed that 1-day delayed effect of PM10 on respiratory admissions of adult males (15-64 years of age), with an RR of 1.18. COH had significant effects on female respiratory hospitalization, especially for 2-day delayed effects on adult females, with RRs of 1.15 and 1.29 using time-series and case-crossover analysis, respectively. There were no significant associations between O3 and TRS with respiratory admissions. These findings provide policy makers with current risks estimates of respiratory hospitalization as a result of poor ambient air quality in a government designated "area of concern."

Do subject characteristics modify the effects of particulate air pollution on daily mortality among the elderly?

OBJECTIVE

Studies have reported associations between mortality and air pollution, but questions subsist on the identification of susceptible subgroups in the population. We studied individual characteristics that modify the relationship between particulate air pollution and mortality among elderly.

METHOD

We examined 527 nonaccidental deaths (197 cardiorespiratory deaths) among the 1469 subjects from the Personnes Agees QUID cohort in Bordeaux between 1988 and 1997. Air pollution was measured as black smoke by urban monitoring background stations. We used a case crossover approach and calculated odds ratio by conditional logistic regression models.

RESULTS

We observed associations between the third lag day and cardiorespiratory mortality for an increase of 10 microg/m3 of black smoke (odds ratio = 1.30, 95% confidence interval: 1.01-1.68).

CONCLUSIONS

Our results provide insight into factors possibly conferring susceptibility to the acute effect of urban air pollution.

Airborne infection with Bacillus anthracis--from mills to mail

The lack of identified exposures in 2 of the 11 cases of bioterrorism-related inhalation anthrax in 2001 raised uncertainty about the infectious dose and transmission of Bacillus anthracis. We used the Wells-Riley mathematical model of airborne infection to estimate 1) the exposure concentrations in postal facilities where cases of inhalation anthrax occurred and 2) the risk for infection in various hypothetical scenarios of exposure to B. anthracis aerosolized from contaminated mail in residential settings. These models suggest that a small number of cases of inhalation anthrax can be expected when large numbers of persons are exposed to low concentrations of B. anthracis. The risk for inhalation anthrax is determined not only by bacillary virulence factors but also by infectious aerosol production and removal rates and by host factors.

Liquid ventilation: an adjunct for respiratory management

Although significant advances in respiratory care have reduced mortality of patients with respiratory failure, morbidity persists, often resulting from iatrogenic mechanisms. Mechanical ventilation with gas has been shown to initiate as well as exacerbate underlying lung injury, resulting in progressive structural damage and release of inflammatory mediators within the lung. Alternative means to support pulmonary gas exchange while preserving lung structure and function are therefore required. Perfluorochemical (PFC) liquids are currently used clinically in a number of ways, such as intravascular PFC emulsions for volume expansion/oxygen carrying/angiography and intracavitary neat PFC liquid for image contrast enhancement or vitreous fluid replacement. As a novel approach to replace gas as the respiratory medium, liquid assisted ventilation (LAV) with PFC liquids has been investigated as an alternative respiratory modality for over 30 years. Currently, there are several theoretical and practical applications of LAV in the immature or mature lung at risk for acute respiratory distress and injury associated with mechanical ventilation.

Impulse oscillometry in healthy nonsmokers and asymptomatic smokers: effects of bronchial challenge with methacholine

The clinical application of respiratory impedance measurements by oscillation techniques for monitoring bronchial challenge testing is hampered by the fact that data in healthy nonsmokers and asymptomatic smokers are very limited. The objective of this study was to analyze the changes in impedance to a methacholine provocation test in healthy nonsmokers and asymptomatic smokers, and to investigate whether smokers show a different response compared to nonsmokers. The response to methacholine challenge was assessed by impulse oscillometry (IOS) (resistance R and reactance X at 5, 10, 15, 20, 25, and 35 Hz) and spirometry (FEV1, MEF50) in 105 healthy subjects (55 nonsmokers: "NS"; 50 asymptomatic smokers: "S") in whom the provocation dose of 2.44 mg methacholine did not result in a fall of FEV1 below 20% predicted of the baseline value. The baseline reactance X values of S were significantly lower compared to NS from 10 to 35 Hz (p < or = 0.01), whereas S and NS did not differ in resistance R over the whole frequency spectrum from 5 to 35 Hz. S showed a significantly higher mean baseline resonant frequency X(f0); i.e., the frequency at which inertial forces are equal and opposite to elastic forces, compared to NS (NS: X(fo) = 10.8+/-2.9 Hz; S = 12.6+/-4.0 Hz, p = 0.01). In both groups methacholine challenge resulted in an increase in R (f) especially at 5 and 10 Hz, and a marked decrease in X(f) over the whole frequency spectrum. In S a significantly higher decrease of postchallenge X5Hz and X10Hz was measured compared to NS (NS: deltaX(5Hz) = -0.044+/-0.003; S: deltaX(5HZ) = -0.083+/-0.013; p = 0.0017. NS: deltaX(10Hz) = -0.050+/-0.001; S: deltaX(10Hz) = -0.082+/-0.017; p = 0.008). R and X at low frequencies showed a three to four times higher postchallenge reaction compared to FEV1. Pre- and postchallenge FEV1 did not correlate with resistance R (f) and reactance X(f) over the whole frequency spectrum. In S perchallenge X(f) values from 10 to 35 HZ were significantly lower, and postchallenge decrease of X5Hz and X10Hz values were significantly higher compared to that of NS, whereas pre- and postchallenge R(f) values were similar in both groups. These results can be explained by changes in the elastic properties of the lung induced by a diffuse subclinical respiratory bronchiolitis.

Detection of particles within the nasal airways before and after nasal decongestion

Cleansing of the air is one of the most important functions of the nose. The aim of this investigation was to determine the influence of decongestion of the nasal mucosa with xylometazoline on the intranasal particle deposition at different sites of the nasal cavity. During respiration of an aerosol of starch particles, the non-deposited particles in the air were laseroptically detected in 10 healthy volunteers by a transnasally placed suction probe at different locations within the nasal cavity. The anterior nasal segment was the main area of intranasal particle deposition before and after decongestion of the nasal mucosa. Particle deposition after nasal decongestion was not significantly different from the values before application of xylometazoline. Decongestion of the nasal mucosa and increase in nasal cavity diameter seems not to influence particle deposition of inhaled and exhaled air within a short period after onset of the maximal decongestive effect of xylometazoline.

Saline aerosol bolus dispersion. II. The effect of conductive airway alteration

In a companion study (Verbanck S, Schuermans D, Vincken W, and Paiva M, J Appl Physiol 90: 1754-1762, 2001), we investigated whether saline aerosol bolus tests could also be used to detect proximal, as opposed to peripheral, airway alterations. We studied 10 never-smokers before and after histamine challenge, obtaining, for various volumetric lung depths (VLD), saline bolus-derived indexes computed by discarding aerosol concentrations below either 50% of the exhaled bolus maximum (half-width, H) or below cutoffs ranging from 5 to 25% (standard deviation, sigma(5%)-sigma(25%)) and skew (sk(5)-sk(25%)). Multiple-breath N(2) washout-derived indexes of conductive (S(cond)) and acinar (S(acin)) ventilation inhomogeneity were also determined. After histamine, S(cond) significantly increased (P = 0.008) whereas S(acin) remained unaffected, indicating purely conductive airway alteration. Consistent with this observation, sk(5%) (or sk(25%)) was increased to the same extent at all VLD, and sigma(5%) was increased preferentially at low VLD. By contrast, H and sigma(25%) displayed preferential increases at high VLD, a pattern similar to that induced by peripheral alterations. The present work shows that proximal airway alteration can be reliably identified by saline bolus tests only if these include measurements at low and high VLD and if bolus dispersion is quantified as a standard deviation with a low cutoff.

Race, gender, and social status as modifiers of the effects of PM10 on mortality

Interest has recently been focused on which populations are most at risk of premature mortality induced by air pollution. This coincides with greater concern about environmental justice. We analyzed total mortality in the four largest US cities with daily measurements of particulate matter less than 10 microns (PM10) and combined the results to determine whether race, sex, and education are potential modifiers of the effects of PM10 on mortality. We computed daily counts of deaths stratified by sex, race, and education in each city and investigated their associations with PM10 in a Poisson regression model. We combined the results by using inverse variance weighted averages. We found evidence of effect modification by sex, with the slope in female deaths one third larger than in male deaths, whereas for social factors and race we found only weak evidence of effect modification. In general, the effect modification appeared modest compared with other reports of substantial effect modification by medical conditions.