Vehicle exhaust exposure in an incident case-control study of adult asthma

Clinical impact and immunological alterations in asthmatic patients allergic to grass pollen subjected to high urban pollution in Madrid

BACKGROUND

The prevalence of asthma has increased in recent decades. Among the reasons for this increase is environmental pollution. Pollutants cause bronchial inflammation and introduce modifications in the pollen, making it more allergenic.

OBJECTIVE

Assess symptoms and medication requirements of asthmatic patients with grass allergies in Madrid (high urban pollution) and Ciudad Real (low pollution), and simultaneously evaluate the in vitro effects that pollen collected in both areas has on the immune cells of patients.

METHODS

During two pollen seasons, patients from both cities were included. The patients recorded their symptoms and the asthma medication they took daily. In both cities, pollen data, pollutants and meteorological variables were evaluated. The response to different cell populations from patients in both areas were analysed after "in vitro" stimulation with pollen from both cities.

RESULTS

The symptoms and medication use of the patients in Madrid was 29.94% higher. The NO₂ concentration in Madrid was triple that of Ciudad Real (33.4 vs. 9.1 µg/m³ of air). All other pollutants had very similar concentrations during the study period. Pollen from the high pollution area caused a significant enhancement of T-CD8+ and NK cells proliferation compared with pollen of low pollution area, independently of the patient's origin.

CONCLUSION

Asthmatic patients from Madrid have a worse clinical evolution than those from Ciudad Real because of higher levels of urban pollution, and this could be driven by the higher capacity of pollen of Madrid to activate T-CD8+ and NK cells.

Air pollution and the development of asthma from birth until young adulthood

BACKGROUND

Air pollution is associated with asthma development in children and adults, but the impact on asthma development during the transition from adolescence to adulthood is unclear. Adult studies lack historical exposures and consequently cannot assess the relevance of exposure during different periods of life. We assessed the relevance of early-life and more recent air pollution exposure for asthma development from birth until early adulthood.

METHODS

We used data of 3687 participants of the prospective Dutch PIAMA (Prevention and Incidence of Asthma and Mite Allergy) birth cohort and linked asthma incidence until age 20 years to estimated concentrations of nitrogen dioxide (NO₂), particulate matter with a diameter <2.5 μm (PM_2.5), <10 μm (PM₁₀), and 2.5-10 μm, and PM_2.5 absorbance ("soot") at the residential address. We assessed overall and age-specific associations with air pollution exposure with discrete time-hazard models, adjusting for potential confounders.

RESULTS

Overall, we found higher incidence of asthma until the age of 20 years with higher exposure to all pollutants at the birth address (adjusted odds ratio (95% CI) ranging from 1.09 (1.01-1.18) for PM₁₀ to 1.20 (1.10-1.32) for NO₂) per interquartile range increase) that were rather persistent with age. Similar associations were observed with more recent exposure defined as exposure at the current home address. In two-pollutant models with particulate matter, associations with NO₂ persisted.

CONCLUSIONS

Exposure to air pollution, especially from motorised traffic, early in life may have long-term consequences for asthma development, as it is associated with an increased risk of developing asthma through childhood and adolescence into early adulthood.

Self-reported traffic-related air pollution and respiratory symptoms among adults in an area with modest levels of traffic

Health effects of traffic-related air pollution (TRAP) concentrations in densely populated areas are previously described. However, there is still a lack of knowledge of the health effects of moderate TRAP levels. The aim of the current study, a population-based survey including 16 099 adults (response rate 33%), was to assess the relationship between TRAP estimates and respiratory symptoms in an area with modest levels of traffic; Telemark County, Norway. Respondents reported respiratory symptoms the past 12 months and two TRAP exposure estimates: amount of traffic outside their bedroom window and time spent by foot daily along a moderate to heavy traffic road. Females reported on average more symptoms than males. Significant relationships between traffic outside their bedroom window and number of symptoms were only found among females, with the strongest associations among female occasional smokers (incidence rate ratio [IRR], 1.75, 95% confidence interval (CI) [1.16–2.62] for moderate or heavy traffic compared to no traffic). Significant relationship between time spent daily by foot along a moderate to heavy traffic road and number of symptoms was found among male daily smokers (IRR 1.09, 95% CI [1.04–1.15] per hour increase). Associations between traffic outside bedroom window and each respiratory symptom were found. Significant associations were primarily detected among females, both among smokers and non-smokers. Significant associations between time spent by foot daily along a moderate to heavy traffic road (per hour) and nocturnal dyspnoea (odds ratio (OR) 1.20, 95% CI [1.05–1.38]), nocturnal chest tightness (OR 1.13 [1.00–1.28]) and wheezing (OR 1.14 [1.02–1.29]) were found among daily smokers, primarily men. Overall, we found significant associations between self-reported TRAP exposures and respiratory symptoms. Differences between genders and smoking status were identified. The findings indicate an association between TRAP and respiratory symptoms even in populations exposed to modest levels of TRAP.

Air pollutants and primary allergy prevention

Background

Air pollutants such as particulate matter (PM2.5) and nitrogen dioxide (NO2) in outdoor air have long been suspected of causing the development of asthma and allergic rhinitis. However, a variety of systematic reviews have reached different conclusions in the last 15 years on whether these air pollutants do in actual fact play a causal role in the onset of asthma, allergic rhinitis, and eczema.

Methods

Based on published systematic reviews and the most recent publications, the current state of knowledge on epidemiological evidence is presented and the potential for primary prevention of these allergic diseases by reducing or avoiding exposure to these air pollutants evaluated.

Results

Despite conducting an extensive literature search, analyzing the most recent results, and focusing on the birth cohort studies most relevant to the question in hand, epidemiological results do not adequately support the concept of a causal relationship between the two air pollutants in question, PM2.5 and NO2, and asthma. Epidemiological studies predominantly show no effect of these air pollutants on allergic sensitization and the onset of allergic rhinitis. The small number of studies that have investigated the link between air pollutants and eczema largely revealed there to be no link.

Conclusion

If the evidence for the causal role of air pollutants in the onset of allergies is inconclusive, one must assume that it is probably not possible to achieve primary prevention of allergies by improving air quality. However, there is sufficient evidence to show that air pollutants can trigger exacerbations of allergic diseases. This alone justifies ensuring that the existing threshold values for air pollutants are adhered to, in order to protect particularly allergy sufferers from health impairments.

Traffic related air pollution and development and persistence of asthma and low lung function

BACKGROUND AND AIMS

Traffic Related Air Pollution (TRAP) exposure is known to exacerbate existing respiratory diseases. We investigated longer term effects of TRAP exposure for individuals with or without existing asthma, and with or without lower lung function.

METHODS

Associations between TRAP exposure and asthma (n = 689) and lung function (n = 599) were investigated in the prospective Tasmanian Longitudinal Health Study (TAHS). TRAP exposure at age 45 years was measured using two methods based on residential address: mean annual NO₂ exposure; and distance to nearest major road. Adjusted multinomial logistic regression was used to model the association between exposure to TRAP at 45 years and changes in asthma and lung function, using three follow ups of TAHS (45, 50 and 53 years).

RESULTS

For those who never had asthma by 45, living <200 m from a major road was associated with increased odds of new asthma that persisted from 50 to 53 years (adjusted Odds Ratio [aOR] 5.20; 95% CI 1.07, 25.4). Asthmatic participants at 45 had an increased risk of persistent asthma up to 53 years if they were living <200 m from a major road, compared with asthmatic participants living >200 m from a major road (aOR = 5.21; 95% CI 1.54, 17.6).

CONCLUSION

For middle aged adults, living <200 m for a major road (a marker of TRAP exposure) influences both the development and persistence of asthma. These findings have public health implications for asthma prevention strategies in primary and secondary settings.

Ambient air pollution, traffic noise and adult asthma prevalence: a BioSHaRE approach

We investigated the effects of both ambient air pollution and traffic noise on adult asthma prevalence, using harmonised data from three European cohort studies established in 2006-2013 (HUNT3, Lifelines and UK Biobank).Residential exposures to ambient air pollution (particulate matter with aerodynamic diameter ≤10 µm (PM10) and nitrogen dioxide (NO2)) were estimated by a pan-European Land Use Regression model for 2007. Traffic noise for 2009 was modelled at home addresses by adapting a standardised noise assessment framework (CNOSSOS-EU). A cross-sectional analysis of 646 731 participants aged ≥20 years was undertaken using DataSHIELD to pool data for individual-level analysis via a "compute to the data" approach. Multivariate logistic regression models were fitted to assess the effects of each exposure on lifetime and current asthma prevalence.PM10 or NO2 higher by 10 µg·m-3 was associated with 12.8% (95% CI 9.5-16.3%) and 1.9% (95% CI 1.1-2.8%) higher lifetime asthma prevalence, respectively, independent of confounders. Effects were larger in those aged ≥50 years, ever-smokers and less educated. Noise exposure was not significantly associated with asthma prevalence.This study suggests that long-term ambient PM10 exposure is associated with asthma prevalence in western European adults. Traffic noise is not associated with asthma prevalence, but its potential to impact on asthma exacerbations needs further investigation.

Susceptibility Factors Relevant for the Association Between Long-Term Air Pollution Exposure and Incident Asthma

In this review, we identified 15 studies in children and 10 studies in adults that assessed the association between long-term exposure to air pollution and incident asthma and that conducted stratified analyses to explore potential susceptibility factors. Overall, adult never-/former smokers seem to be at higher risk of incident asthma due to air pollution. Children without atopy and children from low socioeconomic status families also seem to be at higher risk of incident asthma due to air pollution. While interaction between air pollution and genes involved in the response to oxidative stress pathways have been explored, results are somewhat inconsistent and in need of replication. To evaluate interactions, large sample sizes are necessary, and much more research, including data pooling from existing studies, is needed to further explore susceptibility factors for asthma incidence due to long-term air pollution exposure.

Long-term exposure to traffic pollution and hospital admissions in London

Evidence on the effects of long-term exposure to traffic pollution on health is inconsistent. In Greater London we examined associations between traffic pollution and emergency hospital admissions for cardio-respiratory diseases by applying linear and piecewise linear Poisson regression models in a small-area analysis. For both models the results for children and adults were close to unity. In the elderly, linear models found negative associations whereas piecewise models found non-linear associations characterized by positive risks in the lowest and negative risks in the highest exposure category. An increased risk was observed among those living in areas with the highest socioeconomic deprivation. Estimates were not affected by adjustment for traffic noise. The lack of convincing positive linear associations between primary traffic pollution and hospital admissions agrees with a number of other reports, but may reflect residual confounding. The relatively greater vulnerability of the most deprived populations has important implications for public health.

Outdoor air pollution: a global perspective

Although the air quality in Western countries has continued to improve over the past decades, rapid economic growth in developing countries has left air quality in many cities notoriously poor. The World Health Organization estimates that urban outdoor air pollution is estimated to cause 1.3 million deaths worldwide per year. The primary health concerns of outdoor air pollution come from particulate matter less than 2.5 μm (PM2.5) and ozone (O3). Short-term exposure to PM2.5 increases cardiopulmonary morbidity and mortality. Long-term exposure to PM2.5 has been linked to adverse perinatal outcomes and lung cancer. Excessive O3 exposure is known to increase respiratory morbidity. Patients with chronic cardiopulmonary diseases are more susceptible to the adverse effects of air pollution. Counseling these patients about air pollution and the associated risks should be part of the regular management plans in clinical practice.

Ambient air pollution and adult asthma incidence in six European cohorts (ESCAPE)

BACKGROUND

Short-term exposure to air pollution has adverse effects among patients with asthma, but whether long-term exposure to air pollution is a cause of adult-onset asthma is unclear.

OBJECTIVE

We aimed to investigate the association between air pollution and adult onset asthma.

METHODS

Asthma incidence was prospectively assessed in six European cohorts. Exposures studied were annual average concentrations at home addresses for nitrogen oxides assessed for 23,704 participants (including 1,257 incident cases) and particulate matter (PM) assessed for 17,909 participants through ESCAPE land-use regression models and traffic exposure indicators. Meta-analyses of cohort-specific logistic regression on asthma incidence were performed. Models were adjusted for age, sex, overweight, education, and smoking and included city/area within each cohort as a random effect.

RESULTS

In this longitudinal analysis, asthma incidence was positively, but not significantly, associated with all exposure metrics, except for PMcoarse. Positive associations of borderline significance were observed for nitrogen dioxide [adjusted odds ratio (OR) = 1.10; 95% CI: 0.99, 1.21 per 10 μg/m3; p = 0.10] and nitrogen oxides (adjusted OR = 1.04; 95% CI: 0.99, 1.08 per 20 μg/m3; p = 0.08). Nonsignificant positive associations were estimated for PM10 (adjusted OR = 1.04; 95% CI: 0.88, 1.23 per 10 μg/m3), PM2.5 (adjusted OR = 1.04; 95% CI: 0.88, 1.23 per 5 μg/m3), PM2.5absorbance (adjusted OR = 1.06; 95% CI: 0.95, 1.19 per 10-5/m), traffic load (adjusted OR = 1.10; 95% CI: 0.93, 1.30 per 4 million vehicles × meters/day on major roads in a 100-m buffer), and traffic intensity (adjusted OR = 1.10; 95% CI: 0.93, 1.30 per 5,000 vehicles/day on the nearest road). A nonsignificant negative association was estimated for PMcoarse (adjusted OR = 0.98; 95% CI: 0.87, 1.14 per 5 μg/m3).

CONCLUSIONS

Results suggest a deleterious effect of ambient air pollution on asthma incidence in adults. Further research with improved personal-level exposure assessment (vs. residential exposure assessment only) and phenotypic characterization is needed.

Role of environmental pollutants in liver physiology: special references to peoples living in the oil drilling sites of Assam

The populations residing near polluted sites are more prone to various types of diseases. The important causes of air pollution are the suspended particulate matter, respirable suspended particulate matter, sulfur dioxide and nitrogen dioxide. As limited information is available enumerating the effect of these pollutants on liver physiology of the population living near the polluted sites; in the present study, we tried to investigate their effect on liver of the population residing near the oil drilling sites since birth. In this study, a randomly selected 105 subjects (46 subjects from oil drilling site and 61 subjects from control site) aged above 30 years were taken under consideration. The particulate matter as well as the gaseous pollutants, sulfur dioxide and nitrogen dioxide, were analyzed through a respirable dust sampler. The level of alkaline phosphatase, alanine transaminase and aspartate transaminase enzymes in serum were measured by spectrophotometer. The generalized regression model studies suggests a higher concentration of respirable suspended particulate matter, suspended particulate matter and nitrogen dioxide lowers the alkaline phosphatase level (p<0.0001) by 3.5 times (95% CI 3.1-3.9), 1.5 times (95% CI 1.4 - 1.6) and 12 times (95% CI 10.74 -13.804), respectively in the exposed group. The higher concentration of respirable suspended particulate matter and nitrogen dioxide in air was associated with increase in alanine transaminase level (p<0.0001) by 0.8 times (95% CI 0.589-1.049) and by 2.8 times (95% CI 2.067-3.681) respectively in the exposed group. The increase in nitrogen dioxide level was also associated with increase in aspartate transaminase level (p<0.0001) by 2.5 times (95% CI 1.862 – 3.313) in the exposed group as compared to control group. Thus, the study reveals that long-term exposure to the environmental pollutants may lead to liver abnormality or injury of populations living in polluted sites.

Ambient air pollution exposure and incident adult asthma in a nationwide cohort of U.S. women

RATIONALE

Limited prior data suggest an association between traffic-related air pollution and incident asthma in adults. No published studies assess the effect of long-term exposures to particulate matter less than 2.5 μm in diameter (PM2.5) on adult incident asthma.

OBJECTIVES

To estimate the association between ambient air pollution exposures (PM2.5 and nitrogen dioxide, NO2) and development of asthma and incident respiratory symptoms.

METHODS

The Sister Study is a U.S. cohort study of risk factors for breast cancer and other health outcomes (n = 50,884) in sisters of women with breast cancer (enrollment, 2003-2009). Annual average (2006) ambient PM2.5 and NO2 concentrations were estimated at participants' addresses, using a national land-use/kriging model incorporating roadway information. Outcomes at follow-up (2008-2012) included incident self-reported wheeze, chronic cough, and doctor-diagnosed asthma in women without baseline symptoms.

MEASUREMENTS AND MAIN RESULTS

Adjusted analyses included 254 incident cases of asthma, 1,023 of wheeze, and 1,559 of chronic cough. For an interquartile range (IQR) difference (3.6 μg/m(3)) in estimated PM2.5 exposure, the adjusted odds ratio (aOR) was 1.20 (95% confidence interval [CI] = 0.99-1.46, P = 0.063) for incident asthma and 1.14 (95% CI = 1.04-1.26, P = 0.008) for incident wheeze. For NO2, there was evidence for an association with incident wheeze (aOR = 1.08, 95% CI = 1.00-1.17, P = 0.048 per IQR of 5.8 ppb). Neither pollutant was significantly associated with incident cough (PM2.5: aOR = 0.95, 95% CI = 0.88-1.03, P = 0.194; NO2: aOR = 1.00, 95% CI = 0.93-1.07, P = 0.939).

CONCLUSIONS

Results suggest that PM2.5 exposure increases the risk of developing asthma and that PM2.5 and NO2 increase the risk of developing wheeze, the cardinal symptom of asthma, in adult women.

Trawler fuel exhaust and respiratory impairments: a cross-sectional pilot study among Indian fishermen working in informal sectors

BACKGROUND

An estimated half a billion people are engaged in fishing related occupations in India. Exposure to adulterated fuel exhaust is common among deep-sea fishermen, yet little is known about the potential impacts on the exposure to health.

OBJECTIVE

The aim of this study was to investigate whether fuel emission exposure was associated with increased respiratory impairments among fishermen who were occupationally exposed to fuel exhaust compared to fisherman occupationally unexposed to fuel exhaust.

METHODS

This cross-sectional study compared the prevalence of respiratory symptoms and lung function variables between 152 marine-water and 107 fresh water fishermen considering the use of fuel-driven trawlers. Data were obtained from questionnaires and computerized spirometer.

RESULTS

Fishermen exposed to trawler fuel exhaust reported more than double the number of respiratory symptoms compared to the unexposed fisherman (86·2 vs. 40·2%). They also had a significantly higher chance experiencing chronic cough (adjusted OR = 3·51, 95% confidence interval (CI) = 2·09-6·35), chronic phlegm (8·61, 4·76-15·97), and wheezing (4·29, 2·55-7·61) symptoms. Finally, there was a significant reduction of the ratio of mid portion of forced expiratory flow rate and forced vital capacity (FEF25-75/FVC) in the exposed fishermen compared to the unexposed (0·84 vs. 0·73 second(-1), P = 0·015).

CONCLUSION

Fuel exhaust may negatively impact on the respiratory health of Indian fishermen. More attention and surveillance of occupational health for fishermen in India is needed.

Environment and asthma in adults

The present review addresses recent advances and especially challenging aspects regarding the role of environmental risk factors in adult-onset asthma, for which the causes are poorly established. In the first part of the review, we discuss aspects regarding some environmental risk factors for adult-onset asthma: air pollution, occupational exposures with a focus on an emerging risk represented by exposure to cleaning agents (both at home and in the workplace), and lifestyle and nutrition. The second part is focused on perspectives and challenges, regarding relevant topics on which research is needed to improve the understanding of the role of environmental factors in asthma. Aspects of exposure assessment, the complexity of multiple exposures, the interrelationships of the environment with behavioral characteristics and the importance of studying biological markers and gene-environment interactions to identify the role of the environment in asthma are discussed. We conclude that environmental and lifestyle exposures play an important role in asthma or related phenotypes. The changes in lifestyle and the environment in recent decades have modified the specific risk factors in asthma even for well-recognized risks such as occupational exposures. To better understand the role of the environment in asthma, the use of objective (quantitative measurement of exposures) or modern tools (bar code, GPS) and the development of multidisciplinary collaboration would be very promising. A better understanding of the complex interrelationships between socio-economic, nutritional, lifestyle and environmental conditions might help to study their joint and independent roles in asthma.

Controlled exposure to diesel exhaust causes increased nitrite in exhaled breath condensate among subjects with asthma

OBJECTIVE

To determine whether oxidative/nitrosative stress plays a role in the acute effects of diesel exhaust (DE) on subjects with asthma.

METHODS

In this crossover study, 16 subjects with mild to moderate asthma were exposed to clean filtered air or diluted DE (300 μg/m as PM2.5) for 1 hour with intermittent exercise.

RESULTS

Airway hyperreactivity increased 24 hours after exposure to DE compared with clean filtered air (PC20, 14.9 mg/mL vs 19.7 mg/mL; P = 0.012). Nitrite in exhaled breath condensate was elevated immediately after diesel exposure (P = 0.052) and remained elevated 4 and 24 hours after exposure.

CONCLUSIONS

After exposure to DE, subjects with asthma demonstrated increased airway hyperreactivity and obstruction. Increased nitrite in exhaled breath condensate, in the absence of increased exhaled nitric oxide, suggests a noninflammatory oxidative stress mechanism by which DE affects the lung.

Respiratory health effects of ambient air pollution: an update

There is new evidence for ambient air pollution (AAP) leading to an increased incidence of respiratory diseases in adults. Research has demonstrated that co-exposures have the potential to dramatically augment the effects of AAP and lower the threshold of effect of a given pollutant. Interactions between genes related to oxidative stress and AAP seem to significantly alter the effect of AAP on an individual and population basis. A better definition of vulnerable populations may bolster local or regional efforts to remediate AAP. Advances in genetic research tools have the potential to identify candidate genes that can guide further research.

Air pollution, genetics, and allergy: an update

PURPOSE OF REVIEW

Air pollution has been increasingly associated with diverse adverse health outcomes, including airway diseases. Data suggest that gene-environment interactions are important in this context. However, evidence regarding causal effects of exposure and development of allergic conditions specifically remains immature. We review the developments of the past 18 months regarding air pollution, genetics and epigenetics, and allergy.

RECENT FINDINGS

Conflicting evidence for air pollution as causative in the development of allergic disease persists. However, recent data support the associations between long-term exposure to traffic-related pollutants and newly developed sensitization in children. Studies from India and China demonstrate the global burden of health-related costs attributed to air pollutants and allergic diseases. The effect of exposure seems to be modified by coexposures of allergens as well as genetic variants, particularly those moderating response to oxidative stress. Potential links between exposures and epigenetic (DNA methylation) changes with consequences for disease development are also reinforced.

SUMMARY

Data over the past 18 months support prior literature that air pollutants cause exacerbation, and possibly onset, of allergic disease. Regarding the onset of asthma specifically, the evidence of causality has grown significantly, but it remains difficult to separate allergic from nonallergic asthma. Effect of modification by genetic variants and epigenetic changes warrants further study.

Urban vs. rural factors that affect adult asthma

In this review, our aim was to examine the influence of geographic variations on asthma prevalence and morbidity among adults, which is important for improving our understanding, identifying the burden, and for developing and implementing interventions aimed at reducing asthma morbidity. Asthma is a complex inflammatory disease of multifactorial origin, and is influenced by both environmental and genetic factors. The disparities in asthma prevalence and morbidity among the world's geographic locations are more likely to be associated with environmental exposures than genetic differences. In writing this article, we found that the indoor factors most consistently associated with asthma and asthma-related symptoms in adults included fuel combustion, mold growth, and environmental tobacco smoke in both urban and rural areas. Asthma and asthma-related symptoms occurred more frequently in urban than in rural areas, and that difference correlated with environmental risk exposures, SES, and healthcare access. Environmental risk factors to which urban adults were more frequently exposed than rural adults were dust mites,high levels of vehicle emissions, and a westernized lifestyle.Exposure to indoor biological contaminants in the urban environment is common.The main risk factors for developing asthma in urban areas are atopy and allergy to house dust mites, followed by allergens from animal dander. House dust mite exposure may potentially explain differences in diagnosis of asthma prevalence and morbidity among adults in urban vs. rural areas. In addition, the prevalence of asthma morbidity increases with urbanization. High levels of vehicle emissions,Western lifestyles and degree of urbanization itself, may affect outdoor and thereby indoor air quality. In urban areas, biomass fuels have been widely replaced by cleaner energy sources at home, such as gas and electricity, but in most developing countries, coal is still a major source of fuel for cooking and heating, particularly in winter. Moreover, exposure to ETS is common at home or at work in urban areas.There is evidence that asthma prevalence and morbidity is less common in rural than in urban areas. The possible reasons are that rural residents are exposed early in life to stables and to farm milk production, and such exposures are protective against developing asthma morbidity. Even so, asthma morbidity is disproportionately high among poor inner-city residents and in rural populations. A higher proportion of adult residents of nonmetropolitan areas were characterized as follows:aged 55 years or older, no previous college admission, low household income, no health insurance coverage, and could not see a doctor due to healthcare service availability, etc. In rural areas, biomass fuels meet more than 70% of the rural energy needs. Progress in adopting modern energy sources in rural areas has been slow. The most direct health impact comes from household energy use among the poor, who depend almost entirely on burning biomass fuels in simple cooking devices that are placed in inadequately ventilated spaces. Prospective studies are needed to assess the long-term effects of biomass smoke on lung health among adults in rural areas.Geographic differences in asthma susceptibility exist around the world. The reason for the differences in asthma prevalence in rural and urban areas may be due to the fact that populations have different lifestyles and cultures, as well as different environmental exposures and different genetic backgrounds. Identifying geographic disparities in asthma hospitalizations is critical to implementing prevention strategies,reducing morbidity, and improving healthcare financing for clinical asthma treatment. Although evidence shows that differences in the prevalence of asthma do exist between urban and rural dwellers in many parts of the world, including in developed countries, data are inadequate to evaluate the extent to which different pollutant exposures contribute to asthma morbidity and severity of asthma between urban and rural areas.

The social determinants of health and pandemic H1N1 2009 influenza severity

OBJECTIVES

We explored the effects of social determinants of health on pandemic H1N1 2009 influenza severity and the role of clinical risk factors in mediating such associations.

METHODS

We used multivariate logistic regression with generalized estimating equations to examine the associations between individual- and ecological-level social determinants of health and hospitalization for pandemic H1N1 2009 illness in a case-control study in Ontario, Canada.

RESULTS

During the first pandemic phase (April 23-July 20, 2009), hospitalization was associated with having a high school education or less and living in a neighborhood with high material or total deprivation. We also observed the association with education in the second phase (August 1-November 6, 2009). Clinical risk factors for severe pandemic H1N1 2009 illness mediated approximately 39% of the observed association.

CONCLUSIONS

The main clinical risk factors for severe pandemic H1N1 2009 illness explain only a portion of the associations observed between social determinants of health and hospitalization, suggesting that the means by which the social determinants of health affect pandemic H1N1 2009 outcomes extend beyond clinically recognized risk factors.

Heavy vehicle traffic is related to wheeze among schoolchildren: a population-based study in an area with low traffic flows

BACKGROUND

An association between traffic air pollution and respiratory symptoms among children has been reported. However, the effects of traffic air pollution on asthma and wheeze have been very sparsely studied in areas with low traffic intensity in cold climate with poor dispersion. We evaluated the impact of vehicle traffic on childhood asthma and wheeze by objective exposure assessment.

METHODS

As a part of the Obstructive Lung Disease in Northern Sweden (OLIN) studies, a questionnaire was sent to the families of all children attending first or second grade in Luleå (72,000 inhabitants) in Northern Sweden in 2006. The age of the children was 7-8 years and the participation rate was 98% (n = 1357). Skin prick tests were performed in 1224 (89%) children. The home addresses were given geographical coordinates and traffic counts were obtained from the local traffic authorities. A proximity model of average daily traffic and average daily heavy vehicle traffic within 200 meters from each participant's home address was used. The associations between traffic exposure and asthma and wheeze, respectively, were analysed in an adjusted multiple logistic regression model.

RESULTS

Exposure to high traffic flows was uncommon in the study area; only 15% of the children lived within 200 meters from a road with a traffic flow of ≥8000 vehicles per day. Living closer than 200 meters from a road with ≥500 heavy vehicles daily was associated with current wheeze, odds ratio 1.7 (confidence interval 1.0-2.7). A dose-response relation was indicated. An increased risk of asthma was also seen, however not significant, odds ratio 1.5 (confidence interval 0.8-2.9). Stratified analyses revealed that the effect of traffic exposure was restricted to the non-sensitized phenotype of asthma and wheeze. The agreement between self-reported traffic exposure and objective measurements of exposure was moderate.

CONCLUSIONS

This study showed that already at low levels of exposure, vehicle traffic is related to an increased risk of wheeze among children. Thus, the global burden of traffic air pollution may be underestimated.

Use of a total traffic count metric to investigate the impact of roadways on asthma severity: a case-control study

BACKGROUND

This study had two principal objectives: (i) to investigate the relationship between asthma severity and proximity to major roadways in Perth, Western Australia; (ii) to demonstrate a more accurate method of exposure assessment for traffic pollutants using an innovative GIS-based measure that fully integrates all traffic densities around subject residences.

METHODS

We conducted a spatial case-control study, in which 'cases' were defined as individuals aged under 19 years of age with more severe asthma (defined here as two or more emergency department contacts with asthma in a defined 5-year period) versus age- and gender-matched 'controls' with less severe asthma (defined here as one emergency department contact for asthma). Traffic exposures were measured using a GIS-based approach to determine the lengths of the roads falling within a buffer area, and then multiplying them by their respective traffic counts.

RESULTS

We examined the spatial relationship between emergency department contacts for asthma at three different buffer sizes: 50 metres, 100 metres and 150 metres. No effect was noted for the 50 metre buffer (OR = 1.07; 95% CI: 0.91-1.26), but elevated odds ratios were observed with for crude (unadjusted) estimates OR = 1.21 (95% CI: 1.00-1.46) for 100 metre buffers and OR = 1.25 (95% CI: 1.02-1.54) for 150 metre buffers. For adjusted risk estimates, only the 150 metre buffer yielded a statistically significant finding (OR = 1.24; 95% CI:1.00-1.52).

CONCLUSIONS

Our study revealed a significant 24% increase in the risk of experiencing multiple emergency department contacts for asthma for every log-unit of traffic exposure. This study provides support for the hypothesis that traffic related air pollution increases the frequency of health service contacts for asthma. This study used advanced GIS techniques to establish traffic-weighted buffer zones around the geocoded residential location of subjects to provide an accurate assessment of exposure to traffic emissions, thereby providing a quantification of the ranges over which pollutants may exert a health effect.

A review of low-level air pollution and adverse effects on human health: implications for epidemiological studies and public policy

The aim of this study was to review original scientific articles describing the relationship between atmospheric pollution and damage to human health. We also aimed to determine which of these studies mentioned public policy issues. Original articles relating to atmospheric pollution and human health published between 1995 and 2009 were retrieved from the PubMed database and analyzed. This study included only articles dealing with atmospheric pollutants resulting primarily from vehicle emissions. Three researchers were involved in the final selection of the studies, and the chosen articles were approved by at least two of the three researchers. Of the 84 non-Brazilian studies analyzed, 80 showed an association between atmospheric pollution and adverse effects on human health. Moreover, 66 showed evidence of adverse effects on human health, even at levels below the permitted emission standards. Three studies mentioned public policies aimed at changing emission standards. Similarly, the 29 selected Brazilian studies reported adverse associations with human health, and 27 showed evidence of adverse effects even at levels below the legally permitted emission standards. Of these studies, 16 mentioned public policies aimed at changing emission standards. Based on the Brazilian and non-Brazilian scientific studies that have been conducted, it can be concluded that, even under conditions that are compliant with Brazilian air quality standards, the concentration of atmospheric pollutants in Brazil can negatively affect human health. However, as little discussion of this topic has been generated, this finding demonstrates the need to incorporate epidemiological evidence into decisions regarding legal regulations and to discuss the public policy implications in epidemiological studies.

Adult asthma and traffic exposure at residential address, workplace address, and self-reported daily time outdoor in traffic: A two-stage case-control study

Background

Most epidemiologic studies use traffic at residential address as a surrogate for total traffic exposure when investigating effects of traffic on respiratory health. This study used GIS (Geographical Information Systems) to estimate traffic exposure, not only on residential, but also on workplace address, in addition to survey questions on time spent in traffic during commuting or other daily activities.

The aim was to investigate 1) if there is an association between traffic exposure and prevalence of adult asthma and asthma symptoms, and 2) if so, does this association become stronger using more complete traffic exposure information.

Methods

This study was conducted in two stages: A first cross-sectional survey in Southern Sweden 2004 (n = 24819, 18-80 years, response rate 59%) was followed by a case-control study in 2005 to obtain more detailed exposure and confounder information (n = 2856, asthmatics and controls (1:3), 86% response rate). In the first survey, only residential address was known. In the second survey, questions about workplace addresses and daily time spent in traffic were also included. Residential and workplace addresses were geocoded and linked with GIS to road data and dispersion modelled outdoor concentrations of NO_x (annual mean, 250 × 250 m resolution).

Results

Living within 50 m of a road (measured by GIS) with traffic intensity of >10 cars/minute (compared with no road within this distance) was associated with an increased prevalence of asthma, (OR = 1.8, 95% CI = (1.1-2.8), and with asthma symptoms last 12 months. No statistically significant effects were seen for traffic exposure at workplace address, daily time spent in traffic, or commuting time to work, after adjustment for confounders. A combined total exposure estimate did not give a stronger association with asthma prevalence or asthma symptoms.

Conclusions

Traffic exposure at close proximity to residential address showed association with asthma prevalence and asthma symptoms last 12 months, among adults in southern Sweden. The associations were not stronger when accounting for total traffic exposure. This could reflect exposure misclassfication at workplace address and for other daily time in traffic, but also that residential address remains the main determinant for traffic exposure among adults.

Carbon footprinting of North American emergency medical services systems

OBJECTIVES

This study was undertaken to characterize the carbon emissions from a broad sample of North American emergency medical services (EMS) agencies, and to begin the process of establishing voluntary EMS-related emission targets.

METHODS

Fifteen diverse North American EMS systems with more than 550,000 combined annual responses and serving a population of 6.3 million reported their direct and purchased ("Tier 2") energy consumption for one year. We calculated total carbon dioxide equivalent (CO(2)e) emissions using Environmental Protection Agency, Energy Information Administration, and locality-specific emission conversion factors. We also calculated per-response and population-based emissions. We report descriptive summary data.

RESULTS

Participants included government "third-service" (n = 4), public utility model (n = 1), private contractor (n = 6), and rural rescue squad (n = 4) systems. Call volumes ranged from 800 to 114,280 (median 20,093; interquartile range [IQR] 1,100-55,217). Emissions totaled 46,941,690 pounds of CO(2)e (21,289 metric tons); 75% of emissions were from diesel or gasoline. For systems providing complete Tier 2 data, median emissions per response were 80.7 (IQR 65.1-106.5) pounds of CO(2)e and median emissions per service-area resident were 7.8 (IQR 4.7-11.2) pounds of CO(2)e. Two systems reported aviation fuel consumption for air medical services, with emissions of 2,395 pounds of CO(2)e per flight, or 0.7 pounds of CO(2)e per service-area resident.

CONCLUSION

EMS operations produce substantial carbon emissions, primarily from vehicle-related fuel consumption. The 75th percentiles from our data suggest 106.5 pounds of CO(2)e per unit response and/or 11.2 pounds of CO(2)e per service-area resident as preliminary maximum emission targets. Air medical services can anticipate higher per-flight but lower population-based emissions.

Traffic-related air pollution, oxidative stress genes, and asthma (ECHRS)

BACKGROUND

Traffic-related air pollution is related with asthma, and this association may be modified by genetic factors.

OBJECTIVES

We investigated the role of genetic polymorphisms potentially modifying the association between home outdoor levels of modeled nitrogen dioxide and asthma.

METHODS

Adults from 13 cities of the second European Community Respiratory Health Survey (ECRHS II) were included (n = 2,920), for whom both DNA and outdoor NO(2) estimates were available. Home addresses were geocoded and linked to modeled outdoor NO(2) estimates, as a marker of local traffic-related pollution. We examined asthma prevalence and evaluated polymorphisms in genes involved in oxidative stress pathways [gluthatione S-transferases M1 (GSTM1), T1 (GSTT1), and P1 (GSTP1) and NAD(P)H:quinine oxidoreductase (NQO1)], inflammatory response [tumor necrosis factor alpha (TNFA)], immunologic response [Toll-like receptor 4 (TLR4)], and airway reactivity [adrenergic receptor beta2 (ADRB2)].

RESULTS

The association between modeled NO(2) and asthma prevalence was significant for carriers of the most common genotypes of NQO1 rs2917666 [odds ratio (OR) = 1.54; 95% confidence interval (CI), 1.10-2.24], TNFA rs2844484 (OR = 2.02; 95% CI, 1.30-3.27). For new-onset asthma, the effect of NO(2) was significant for the most common genotype of NQO1 rs2917666 (OR = 1.52; 95% CI, 1.09-2.16). A significant interaction was found between NQO1 rs2917666 and NO(2) for asthma prevalence (p = 0.02) and new-onset asthma (p = 0.04).

CONCLUSIONS

Genetic polymorphisms in the NQO1 gene are related to asthma susceptibility among persons exposed to local traffic-related air pollution. This points to the importance of antioxidant pathways in the protection against the effects of air pollution on asthma.

Home outdoor NO2 and new onset of self-reported asthma in adults

BACKGROUND

Few studies have investigated new onset of asthma in adults in relation to air pollution. The aim of this study is to investigate the association between modeled background levels of traffic-related air pollution at the subjects' home addresses and self-reported asthma incidence in a European adult population.

METHODS

Adults from the European Respiratory Health Survey were included (n = 4185 from 17 cities). Subjects' home addresses were geocoded and linked to outdoor nitrogen dioxide (NO2) estimates, as a marker of local traffic-related pollution. We obtained this information from the 1-km background NO2 surface modeled in APMoSPHERE (Air Pollution Modelling for Support to Policy on Health and Environmental Risk in Europe). Asthma incidence was defined as reporting asthma in the follow-up (1999 to 2001) but not in the baseline (1991 to 1993).

RESULTS

A positive association was found between NO2 and asthma incidence (odds ratio 1.43; 95% confidence interval = 1.02 to 2.01) per 10 microg/m. Results were homogeneous among centers (P value for heterogeneity = 0.59).

CONCLUSIONS

We found an association between a marker of traffic-related air pollution and asthma incidence in European adults.

Traffic exposure associated with allergic asthma and allergic rhinitis in adults. A cross-sectional study in southern Sweden

Background

There is conflicting evidence that traffic-related air pollution is a risk factor for allergic conditions. Few studies have investigated this in adults. In adults, a high proportion of asthma, rhinitis and eczema is triggered by non-allergic factors. We investigated traffic as a risk factor for allergic versus non-allergic asthma and rhinitis, and eczema, in adults.

A questionnaire from 2000 (n = 9319, 18–77 years) provided individual data about disease outcome and self-reported traffic exposure. Additional exposure assessments were obtained using Geographical Informations Systems (GIS). Residential addresses were linked to the national Swedish Road Database and to a pollutant database with modelled annual means of NO_x (Nitrogen Oxids).

Results

Living within 100 m from a road with a traffic intensity of >10 cars/min (24 hour mean) was associated with prevalence of current asthma reported to be triggered by allergic factors (OR = 1.83, 95% CI = 1.23–2.72) and with allergic rhinitis (OR = 1.30, 95%CI = (1.05–1.61). No relation was seen with asthma or rhinitis triggered by other factors. Living within 100 m of a road with >10 cars/min was also associated with hand-eczema during the last 12 months (OR = 1.63, 95% CI = 1.19–2.23), but not with allergic eczema or diagnosed hand-eczema. Consistent results were seen using self-reported traffic, but the associations with NO_x were less consistent.

Conclusion

Exposure to traffic was associated with a higher prevalence of allergic asthma and allergic rhinitis, but not with asthma or rhinitis triggered by non-allergic factors. This difference was suggested by the overall pattern, but only clear using GIS-measured traffic intensity as a proxy for traffic exposure. An association was also found with hand-eczema during the last 12 months. We suggest that asthma and rhinitis should not be treated as homogenous groups when estimating effects from traffic in adults.

Traffic-related air pollution associated with prevalence of asthma and COPD/chronic bronchitis. A cross-sectional study in Southern Sweden

Background

There is growing evidence that air pollution from traffic has adverse long-term effects on chronic respiratory disease in children, but there are few studies and more inconclusive results in adults. We examined associations between residential traffic and asthma and COPD in adults in southern Sweden. A postal questionnaire in 2000 (n = 9319, 18–77 years) provided disease status, and self-reported exposure to traffic. A Geographical Information System (GIS) was used to link geocoded residential addresses to a Swedish road database and an emission database for NOx.

Results

Living within 100 m of a road with >10 cars/minute (compared with having no heavy road within this distance) was associated with prevalence of asthma diagnosis (OR = 1.40, 95% CI = 1.04–1.89), and COPD diagnosis (OR = 1.64, 95%CI = 1.11–2.4), as well as asthma and chronic bronchitis symptoms. Self-reported traffic exposure was associated with asthma diagnosis and COPD diagnosis, and with asthma symptoms. Annual average NOx was associated with COPD diagnosis and symptoms of asthma and chronic bronchitis.

Conclusion

Living close to traffic was associated with prevalence of asthma diagnosis, COPD diagnosis, and symptoms of asthma and bronchitis. This indicates that traffic-related air pollution has both long-term and short-term effects on chronic respiratory disease in adults, even in a region with overall low levels of air pollution.

A systematic review of the relation between long-term exposure to ambient air pollution and chronic diseases

We conducted a systematic review of all studies published between 1950 and 2007 of associations between long-term exposure to ambient air pollution and the risks in adults of nonaccidental mortality and the incidence and mortality from cancer and cardiovascular and respiratory diseases. We searched bibliographic databases for cohort and case-control studies, abstracted characteristics of their design and conduct, and synthesized the quantitative findings in tabular and graphic form. We assessed heterogeneity, estimated pooled effects for specific pollutants, and conducted sensitivity analyses according to selected characteristics of the studies. Our analysis showed that long-term exposure to PM2.5 increases the risk of nonaccidental mortality by 6% per a 10 microg/m3 increase, independent of age, gender, and geographic region. Exposure to PM2.5 was also associated with an increased risk of mortality from lung cancer (range: 15% to 21% per a 10 microg/m3 increase) and total cardiovascular mortality (range: 12% to 14% per a 10 microg/m3 increase). In addition, living close to busy traffic appears to be associated with elevated risks of these three outcomes. Suggestive evidence was found that exposure to PM2.5 is positively associated with mortality from coronary heart diseases and exposure to SO2 increases mortality from lung cancer. For the other pollutants and health outcomes, the data were insufficient data to make solid conclusions.

Recent evidence for adverse effects of residential proximity to traffic sources on asthma

PURPOSE OF REVIEW

A growing body of evidence indicates that residential proximity to traffic sources increases the risk for asthma and asthma exacerbations. In this review we have considered publications from 2006-2007 that examined the impact of residential traffic-related exposures on asthma occurrence and severity.

RECENT FINDINGS

In these studies, exposures were estimated using traffic metrics based on residential distances from major roads and freeways, traffic densities around homes, and models of traffic exposure. Overall, residential proximity to traffic sources was associated with increased asthma occurrence and exacerbations in both children and adults. Land-use regression models were superior to individual traffic metrics in explaining the variability of traffic-related pollutants. Susceptibility may also play a role in variation in the effects of traffic on asthma.

SUMMARY

There is consistent evidence that living near traffic sources is associated with asthma occurrence and exacerbations. Future studies have the opportunity to improve exposure estimates by measuring traffic-related pollutants near homes and schools and including time/activity patterns in prediction models. Further research is also warranted to investigate the differential impact of traffic by genetic and other susceptibility factors and to identify specific pollutants that underlie the adverse effect of traffic on asthma.

Perceived annoyance and asthmatic symptoms in relation to vehicle exhaust levels outside home: a cross-sectional study

BACKGROUND

Exhaust emissions from vehicles is a well known problem with both epidemiological and experimental studies showing increasing adverse health effects with elevating levels. Many of the studies concerning vehicle exhausts and health are focused on health outcomes where the proportion attributed to exhaust is low, while there is less information on early and more frequent subjective indicators of adverse effects.

METHODS

The primary aim of this study was to study perceived annoyance in relation to vehicle exhaust concentrations using modelled levels of nitrogen dioxide outside the home as an indicator with high spatial resolution. Almost 2800 persons in a random sample from three Swedish cities (Umea, Uppsala and Gothenburg) responded to our questionnaire. Questions were asked to determine the degree of annoyance related to vehicle exhausts and also the prevalence of irritating and asthmatic symptoms. Exposure was described for each participants home address by meteorological dispersion models with a 50 meter resolution.

RESULTS

We found a significant increase of peoples' self-assessed annoyance with rising levels of NO2. The odds of being very annoyed by vehicle exhausts increased by 14% per 1 microg/m3 increase of the NO2 level (odds ratio (OR) = 1.14, 95% confidence interval (CI) = 1.11-1.18), and the odds of reporting the air as daily or almost daily irritating increased by 9% (OR = 1.09, 95% CI = 1.05-1.13). Also the odds of reporting asthmatic symptoms increased significantly with elevated NO2 levels (OR = 1.04, 95% CI = 1.01-1.07).

CONCLUSION

This study found the degree of annoyance related to vehicle exhaust and irritating and asthmatic symptoms to be significantly dependent on the levels of traffic related pollutants outside the home. The detailed exposure assessment lowers the degree of misclassification as compared to between-city analyses, which makes the results more accurate and applicable on the local scale.

Asthma and air quality

PURPOSE OF REVIEW

There is evidence for an association between asthma and air pollutants, including ozone, NO2 and particulate matter. Since these pollutants are ubiquitous in the urban atmosphere and typically correlated with each other it has been difficult to ascertain the specific sources of air pollution responsible for the observed effects. Similarly, uncertainty in determining a causal agent, or multiple agents, has complicated efforts to identify the mechanisms involved in pollution-mediated asthma events and whether air pollution may cause asthma as well as exacerbate preexisting cases.

RECENT FINDINGS

Numerous studies have examined specific sources of air pollution and their relationship to asthma. This review summarizes recent work conducted, specifically, on traffic pollution and presents results that elucidate several plausible biological mechanisms for the observed effects. Of note are studies linking susceptibility to several genetic polymorphisms. Together, these studies suggest that remaining uncertainties in the asthma-air pollution association may be addressed through enhanced assessment of both exposures and outcomes.

SUMMARY

Air-pollution research is evolving rapidly; in the near future, clinicians and public health agencies may be able to use this new information to provide recommendations for asthmatics that go beyond only paying attention to the air-pollution forecast.