Health exposure assessment and policy analysis

Many of the existing models in regard to health, environment and development answer very few questions of concern to health planners. The models need to be precise and specific. Potential impacts of environmental pollutants on human health are evaluated on the basis of quantitative health risk assessment (QHRA). Distribution and transport of pollutants; human exposure to the pollutant; and toxicology and pharmacokinetics of a pollutant in human beings are the elements involved in health modelling.

In the present paper, age‐specific human exposures to air pollutants (suspended particulate matter, sulphur dioxide and nitrogen dioxide) have been analysed and estimated for two cities, Delhi and Nagpur, in India. The analysis, which is based on age‐specific breathing rates, body weights and occupancy factors for residential, commercial and industrial zones, highlights the exposure‐risks due to suspended particulate matter (SPM), SO₂ and NO₂. Amongst several interesting inferences which the analysis brings out is the fact that children suffer most from air pollution induced health‐risks. Interfacing the present model with toxicokinetic and pharmaco‐dynamic models will facilitate more precise quantification and assessment of health‐risks.     

Traffic related air pollution and acute hospital admission for respiratory diseases in Drammen, Norway 1995–2000

The aim of this study was to estimate the associations between seven ambient air pollutants [particulate matter (PM₁₀), nitrous dioxide (NO₂), sulfur dioxide (SO₂), ozone (O₃), benzene, formaldehyde and toluene] and acute hospital admissions for respiratory diseases in Drammen, Norway 1995–2000. Time-series analysis of counts was performed by means of generalized additive models with log link and Poisson distribution. The results showed that benzene was the pollutant having the strongest association with respiratory diseases for the total study period, the relative risk of an interquartile increase of benzene was 1.095 with 95% confidence interval: 1.031–1.163. The corresponding results were 1.049 (0.990–1.112) for formaldehyde, 1.044 (1.000–1.090) for toluene, 1.064 (1.019–1.111) for NO₂, 1.043 (1.011–1.075) for SO₂, 0.990 (0.936–1.049) for O₃ and 1.022 (0.990–1.055) for PM₁₀. Dividing the total study period into two 3-year periods, there was a substantial reduction in the exposure levels of the volatile organic compounds (benzene, formaldehyde and toluene) from the first to the second period. Separate analyses for the second time period showed weaker association between these pollutants and the health outcome. This study provides further evidence for short-term respiratory health effects of traffic related air pollution.     

Associations between daily mortalities from respiratory and cardiovascular diseases and air pollution in Hong Kong, China

Objective: To investigate the association between ambient concentrations of air pollutants and respiratory and cardiovascular mortalities in Hong Kong.

Methods: Retrospective ecological study. A Poisson regression of concentrations of daily air pollutants on daily mortalities for respiratory and cardiovascular diseases in Hong Kong from 1995 to the end of 1998 was performed using the air pollution and health: the European approach (APHEA) protocol. The effects of time trend, seasonal variations, temperature, and humidity were adjusted. Autocorrelation and overdispersion were corrected. Daily concentrations of nitrogen dioxide (NO₂), sulphur dioxide (SO₂), ozone (O₃), and particulate matter <10 µm in aerodynamic diameter (PM₁₀) were averaged from eight monitoring stations in Hong Kong. Relative risks (RRs) of respiratory and cardiovascular mortalities (per 10 µg/m³ increase in air pollutant concentration) were calculated.

Results: Significant associations were found between mortalities for all respiratory diseases and ischaemic heart diseases (IHD) and the concentrations of all pollutants when analysed singly. The RRs for all respiratory mortalities (for a 10 µg/m³ increase in the concentration of a pollutant) ranged from 1.008 (for PM₁₀) to 1.015 (for SO₂) and were higher for chronic obstructive pulmonary diseases (COPD) with all pollutants except SO₂, ranging from 1.017 (for PM₁₀) to 1.034 (for O₃). RRs for IHD ranged from 1.009 (for O₃) to 1.028 (for SO₂). In a multipollutant model, O₃ and SO₂ were significantly associated with all respiratory mortalities, whereas NO₂ was associated with mortality from IHD. No interactions were detected between any of the pollutants or with the winter season. A dose-response effect was evident for all air pollutants. Harvesting was not found in the short term.

Conclusions: Mortality risks were detected at current ambient concentrations of air pollutants. The associations with the particulates and some gaseous pollutants when analysed singly were consistent with many reported in temperate countries. PM₁₀ was not associated with respiratory or cardiovascular mortalities in multipollutant analyses.

     

Respiratory health effects among schoolchildren and their relationship to air pollutants in Korea

The objective of this study is to investigate the relationship between five air pollutants (PM₁₀, SO₂, NO₂, O₃, CO) measured on the daily basis, and adverse health symptoms using epidemiological surveillance data. The generalized estimated equation (GEE) model, a logistic regression analysis model, was used to estimate the effects of air pollution on children's daily health symptoms, focusing on the morbidity including both respiratory and allergic symptoms in four different cities. Analysis of the effects of each pollutant on children's respiratory and allergic symptoms demonstrated that CO affected all symptoms in all the study areas. When the concentration of SO₂ and NO₂ was elevated, upper respiratory symptoms increased significantly. In contrast, when the concentration of O₃ rose, the symptoms decreased significantly. The relationship between measured concentrations and health symptoms was site-dependent for each pollutant.     

中国空气污染与不良出生结局的研究进展

目的 对中国空气污染与不良出生结局的相关研究进展进行综述。方法 通过检索万方、中国知网（CNKI）、PubMed、Science Direct、Web of Science等数据库2016年6月30日前发表的中国人群空气污染物暴露与不良出生结局相关文献,按照制定的纳入排除标准进行筛选,并对纳入的27篇文献进行综述。结果 中国孕产妇妊娠期间空气动力学直径≤10 μm的颗粒物（PM₁₀）、二氧化硫（SO₂）、二氧化氮（NO₂）、总悬浮颗粒物（TSP）暴露可能增加低出生体重发病风险;妊娠期间暴露PM₁₀、SO₂、NO₂可能增加早产发病风险;妊娠期间暴露SO₂、NO₂、臭氧（O₃）、PM₁₀可能增加先天性心脏缺陷及其他出生缺陷发病风险。结论 中国孕产妇妊娠期间空气污染物暴露可能增加不良出生结局发病风险,需进一步开展研究探讨其相关性。     

Respiratory Effects of Air Pollutants among Asthmatics in Central Taiwan

The authors investigated the relationship between respiratory effects and air pollutants among asthmatics in central Taiwan. A total of 12,926 subjects were selected from 8 junior high schools. Data about monthly hospital admissions for respiratory illnesses were collected over a period of 1 yr from the National Insurance Bureau. Data included how frequently subjects purchased medication and the respiratory symptoms recorded by clinic and hospital personnel. Pulmonary function tests were administered to 20% of the total study population, which was selected randomly. Data about monthly levels of air pollutants (i.e., particulate matter 10 μm and less [PM₁₀], ozone [O₃], sulfur dioxide [SO₂], and nitrogen dioxide [NO₂]) were provided by Taiwan's Environmental Protection Agency. The prevalence rates of asthma were correlated significantly with NO₂ (r = .63) and O₃ (r= .51) concentrations. Levels of NO₂ and PM₁₀ were correlated significantly with monthly hospital admissions. Forced vital capacity, forced expiratory volume in 1 sec, and peak expiratory flow for asthmatics in central Taiwan were 6–11 % lower than normal predicted values for the general Taiwanese student population, adjusted for age, height, and weight. In conclusion, the increased risk of asthma and the frequency of monthly hospital admissions among asthmatics may be correlated positively with pollution levels—especially NO₂ and PM₁₀.     

Does exposure to air pollution in urban parks have socioeconomic, racial or ethnic gradients?

Little is known about the levels of air pollution at public parks where regular exercise takes place or in park-adjacent neighborhoods where people have easy access to parks. In this study we investigated the ambient concentrations of criteria pollutants nitrogen dioxide (NO₂), fine particulate (PM_2.5) and ozone (O₃) at public parks and in park-adjacent neighborhoods for metropolitan Los Angeles. Socioeconomic and racial-ethnic inequalities in exposure to the three criteria pollutants were also investigated using multiple linear regression models. In addition, differences in inhalation doses from breathing the three +criteria pollutants were investigated for the top and bottom quartile racial composition in the parks and neighborhoods. Our research showed that although public parks had on average the lowest pollutant concentrations of NO₂ and PM_2.5, they had relatively high O₃ concentrations. Park-adjacent neighborhoods, by contrast, had the highest NO₂ and PM_2.5 concentrations, but the lowest O₃ concentrations. Higher exposures to NO₂ and PM_2.5 were systematically identified for the lower socioeconomic position or higher minority population neighborhoods. For children and adolescents aged 6–15 engaging in high and moderate intensity activities in and around public parks, those from the top quartile of primarily Hispanic neighborhoods had much higher (63%) inhaled doses of NO₂ compared to the bottom quartile counterpart. PM_2.5 showed a similar but less pronounced pattern of inhalation doses. Evidence of socioeconomic and racial-ethnic gradients was found in air pollution exposure and inhalation doses in and around the urban parks in Los Angeles. This suggests that patterns of exposure inequality found in other environmental justice research are present in exposures in and around urban parks.     

Cell type specificity of female lung cancer associated with sulfur dioxide from air pollutants in Taiwan: An ecological study

Background  

Many studies have examined the association between air pollutants (including sulfur dioxide [SO₂], carbon monoxide [CO], nitrogen dioxide [NO₂], nitric oxide [NO], ozone [O₃], and particulate matter < 10 μm [PM₁₀]) and lung cancer. However, data from previous studies on pathological cell types were limited, especially for SO₂ exposure. We aimed to explore the association between SO₂ exposure from outdoor air pollutants and female lung cancer incidence by cell type specificity.     

Health effect of mixtures of ozone,nitrogen dioxide,and fine particulates in 85 US counties

Despite substantial improvements in ambient air quality in the past decades, ozone (O₃), nitrogen dioxide (NO₂), and fine particulate matter (PM_2.5) remain as concerns. As these pollutants exist as mixtures in ambient environments, some combinations of these pollutants may be more harmful to human health than other combinations. Identifying harmful pollutant mixtures can help develop multi-pollutant control strategies to better protect health. Current methods exhibit limitations in identifying harmful mixtures. We aim to identify harmful compositions of three-pollutant mixtures in 85 US counties during 1999–2010. We developed a new method called PANCAKE to quantify O₃-NO₂-PM_2.5 mixtures. O₃-NO₂-PM_2.5 mixtures are categorized into 27 composition types based on combinations of different O₃, NO₂, and PM_2.5 levels. We identified harmful compositions by estimating the effect of each composition of O₃-NO₂-PM_2.5 mixture compared to the reference composition on cardiovascular admissions among Medicare patients. We found that a mixture with relatively low levels of some pollutants combined with relatively high levels of other pollutants can be equally or more harmful than a mixture with high levels of all pollutants. Eight out of the 27 composition types, often with NO₂ levels >?17.3 ppb and PM_2.5 levels >?8.8 μg/m³ combined with any levels of O₃, were associated with significantly increased cardiovascular admission rates compared to the reference composition. These harmful compositions overall occurred in about 40–50% of days in winter, metropolitan areas, or the East North Central region. Mixture composition plays an important role in determining health risks and may be worth considering when developing air pollution control strategies.     

Ambient PM2.5, O3, and NO2 Exposures and Associations with Mortality over 16 Years of Follow-Up in the Canadian Census Health and Environment Cohort (CanCHEC)

Background

Few studies examining the associations between long-term exposure to ambient air pollution and mortality have considered multiple pollutants when assessing changes in exposure due to residential mobility during follow-up.

Objective

We investigated associations between cause-specific mortality and ambient concentrations of fine particulate matter (≤ 2.5 μm; PM_2.5), ozone (O₃), and nitrogen dioxide (NO₂) in a national cohort of about 2.5 million Canadians.

Methods

We assigned estimates of annual concentrations of these pollutants to the residential postal codes of subjects for each year during 16 years of follow-up. Historical tax data allowed us to track subjects’ residential postal code annually. We estimated hazard ratios (HRs) for each pollutant separately and adjusted for the other pollutants. We also estimated the product of the three HRs as a measure of the cumulative association with mortality for several causes of death for an increment of the mean minus the 5th percentile of each pollutant: 5.0 μg/m³ for PM_2.5, 9.5 ppb for O₃, and 8.1 ppb for NO₂.

Results

PM_2.5, O₃, and NO₂ were associated with nonaccidental and cause-specific mortality in single-pollutant models. Exposure to PM_2.5 alone was not sufficient to fully characterize the toxicity of the atmospheric mix or to fully explain the risk of mortality associated with exposure to ambient pollution. Assuming additive associations, the estimated HR for nonaccidental mortality corresponding to a change in exposure from the mean to the 5th percentile for all three pollutants together was 1.075 (95% CI: 1.067, 1.084). Accounting for residential mobility had only a limited impact on the association between mortality and PM_2.5 and O₃, but increased associations with NO₂.

Conclusions

In this large, national-level cohort, we found positive associations between several common causes of death and exposure to PM_2.5, O₃, and NO₂.

Citation

Crouse DL, Peters PA, Hystad P, Brook JR, van Donkelaar A, Martin RV, Villeneuve PJ, Jerrett M, Goldberg MS, Pope CA III, Brauer M, Brook RD, Robichaud A, Menard R, Burnett RT. 2015. Ambient PM_2.5, O₃, and NO₂ exposures and associations with mortality over 16 years of follow-up in the Canadian Census Health and Environment Cohort (CanCHEC). Environ Health Perspect 123:1180–1186; http://dx.doi.org/10.1289/ehp.1409276     

Ambient air pollution and lipoprotein-associated phospholipase A₂ in survivors of myocardial infarction

Background: Increasing evidence suggests a proatherogenic role for lipoprotein-associated phospholipase A₂ (Lp-PLA2). A meta-analysis of published cohorts has shown that Lp-PLA2 is an independent predictor of coronary heart disease events and stroke.Objective: In this study, we investigated whether the association between air pollution and cardiovascular disease might be partly explained by increased Lp-PLA2 mass in response to exposure.Methods: A prospective longitudinal study of 200 patients who had had a myocardial infarction was performed in Augsburg, Germany. Up to six repeated clinical examinations were scheduled every 4–6 weeks between May 2003 and March 2004. Supplementary to the multicenter AIRGENE protocol, we assessed repeated plasma Lp-PLA2 concentrations. Air pollution data from a fixed monitoring site representing urban background concentrations were collected. We measured hourly means of particle mass [particulate matter (PM) < 10 µm (PM₁₀) and PM < 2.5 µm (PM_2.5) in aerodynamic diameter] and particle number concentrations (PNCs), as well as the gaseous air pollutants carbon monoxide (CO), sulfur dioxide (SO₂), ozone (O₃), nitric oxide (NO), and nitrogen dioxide (NO₂). Data were analyzed using mixed models with random patient effects.Results: Lp-PLA2 showed a positive association with PM₁₀, PM_2.5, and PNCs, as well as with CO, NO₂, NO, and SO₂ 4–5 days before blood withdrawal (lag 4–5). A positive association with O₃ was much more immediate (lag 0). However, inverse associations with some pollutants were evident at shorter time lags.Conclusion: These preliminary findings should be replicated in other study populations because they suggest that the accumulation of acute and subacute effects or the chronic exposure to ambient particulate and gaseous air pollution may result in the promotion of atherosclerosis, mediated, at least in part, by increased levels of Lp-PLA2.     

GSTM1, GSTT1, and GSTP1 Polymorphisms and Associations between Air Pollutants and Markers of Insulin Resistance in Elderly Koreans

Background: Previous studies have suggested that diabetes mellitus (DM) is an outcome of exposure to air pollution, and metabolic detoxification genes affect air pollution–related outcomes.Objectives: We evaluated associations between air pollutants and markers of insulin resistance (IR), an underlying mechanism of type 2 DM, and effect modification by GSTM1, GSTT1, and GSTP1 genotypes among elderly participants in the Korean Elderly Environmental Panel (KEEP) study.Methods: We recruited 560 people ≥ 60 years of age and obtained blood samples from them up to three times between 2008 and 2010. For air pollution exposure, we used ambient air pollutant [i.e., particulate matter ≤ 10 µm in diameter (PM₁₀), sulfur dioxide (SO₂), ozone (O₃), and nitrogen dioxide (NO₂)] monitoring data. We measured levels of fasting glucose and insulin and derived the homeostatic model assessment (HOMA) index to assess IR. Mixed-effect models were used to estimate associations between air pollutants and IR indices on the same day or lagged up to 10 days prior, and effect modification by GSTM1, GSTT1, and GSTP1 genotypes.Results: Interquartile range increases in PM₁₀, O₃, and NO₂ were significantly associated with IR indices, depending on the lag period. Associations were stronger among participants with a history of DM and among those with GSTM1-null, GSTT1-null, and GSTP1 AG or GG genotypes.Conclusions: Our results suggest that PM₁₀, O₃, and NO₂ may increase IR in the elderly, and that GSTM1-null, GSTT1-null, and GSTP1 AG or GG genotypes may increase susceptibility to potential effects of ambient air pollutants on IR.     

Health effects of short-term inhalation of nitrogen dioxide and ozone mixtures.

The effects of single and multiple daily 3-hour exposures to nitrogen dioxide (NO₂) and ozone (O₃) mixtures on the resistance to streptococcal pneumonia were investigated. The concentrations of NO₂ ranged from 1.5 to 5.0 ppm, and those of O₃, from 0.05 to 0.5 ppm. The effect of a single exposure to the mixture was additive, whereby the excess mortality rates were equivalent to those induced by the inhalation of each individual pollutant. The ability to clear inhaled bacteria from the lungs was diminished in mice exposed to the NO₂O₃ mixtures for 3 hours. This impairment was manifested by the increased frequency of isolation of Streptococcus from the lungs for up to 6 days after the respiratory challenge. Excess mortalities observed after 20 daily 3-hour exposures suggested that a synergistic effect might be present upon repeated inhalation of pollutant mixtures, that made them more effective in reducing resistance to respiratory infection. The results emphasize the need for the establishment of primary air quality standards for short-term NO₂ exposures.     

Air pollution and population health: a global challenge

“Air pollution and population health” is one of the most important environmental and public health issues. Economic development, urbanization, energy consumption, transportation/motorization, and rapid population growth are major driving forces of air pollution in large cities, especially in megacities. Air pollution levels in developed countries have been decreasing dramatically in recent decades. However, in developing countries and in countries in transition, air pollution levels are still at relatively high levels, though the levels have been gradually decreasing or have remained stable during rapid economic development. In recent years, several hundred epidemiological studies have emerged showing adverse health effects associated with short-term and long-term exposure to air pollutants. Time-series studies conducted in Asian cities also showed similar health effects on mortality associated with exposure to particulate matter (PM), sulfur dioxide (SO₂), nitrogen dioxide (NO₂) and ozone (O₃) to those explored in Europe and North America. The World Health Organization (WHO) published the “WHO Air Quality Guidelines (AQGs), Global Update” in 2006. These updated AQGs provide much stricter guidelines for PM, NO₂, SO₂ and O₃. Considering that current air pollution levels are much higher than the WHO-recommended AQGs, interim targets for these four air pollutants are also recommended for member states, especially for developing countries in setting their country-specific air quality standards. In conclusion, ambient air pollution is a health hazard. It is more important in Asian developing countries within the context of pollution level and population density. Improving air quality has substantial, measurable and important public health benefits.     

Joint Impact of Key Air Pollutants on COVID-19 Severity: Prediction based on Toxicogenomic Data Analysis

Considering that some researchers point to a possible influence of air pollution on COVID-19 transmission, severity, and death rate, the aim of our in silico study was to determine the relationship between the key air pollutants [sulphur dioxide (SO), carbon monoxide (CO), ₂particulate matter (PM_x), nitrogen dioxide (NO₂), and ozone (O₃)] and COVID-19 complications using the publicly available toxicogenomic analytical and prediction tools: (i) Comparative Toxicogenomic Database (CTD) to identify genes common to air pollutants and COVID-19 complications; (ii) GeneMANIA to construct a network of these common and related genes; (iii) ToppGene Suite to extract the most important biological processes and molecular pathways; and (iv) DisGeNET to search for the top gene-disease pairs. SO₂, CO, PM_x, NO₂, and O₃ interacted with 6, 6, 18, 9, and 12 COVID-19-related genes, respectively. Four of these are common for all pollutants (IL10, IL6, IL1B, and TNF) and participate in most (77.64 %) physical interactions. Further analysis pointed to cytokine binding and cytokine-mediated signalling pathway as the most important molecular function and biological process, respectively. Other molecular functions and biological processes are mostly related to cytokine activity and inflammation, which might be connected to the cytokine storm and resulting COVID-19 complications. The final step singled out the link between the CEBPA gene and acute myelocytic leukaemia and between TNFRSF1A and TNF receptor-associated periodic fever syndrome. This indicates possible complications in COVID-19 patients suffering from these diseases, especially those living in urban areas with poor air quality.Key words: carbon monoxide, cytokines, disease complications, in silico, nitrogen dioxide, ozone, particulate matter, SARS-CoV-2, sulphur dioxide     

Ambient air pollution and emergency department visits among children and adults in Casablanca,Morocco

This study presents the relationships between ambient air pollutants and morbidity and emergency department visits among children and adults performed in Great Casablanca, the most populated and economic region in Morocco. This research was analyzed using conditional Poisson model for the period 2011–2013. In the period of study, the daily average concentrations of SO₂, NO₂, O₃ and PM₁₀ in Casablanca were 209.4 µg/m³, 61 µg/m³, 113.2 µg/m³ and 75.1 µg/m³, respectively. In children less than 5 years old, risk of asthma could be increased until 12% per 10 µg/m³ increase in NO₂, PM10, SO₂ and O₃. In children over 5 years and adults, an increase of 10 µg/m³ air pollutant can cause an increase until 3% and 4% in respiratory consultations and acute respiratory infection, respectively. Similarly, impact on emergency department visits due to respiratory and cardiac illness was established. Our results suggest a not negligible impact on morbidity of outdoor air pollution by NO₂, SO₂, O₃, and PM₁₀.     

Associations between size-segregated particle number concentrations and respiratory mortality in Beijing, China

Numerous studies have described the adverse associations between particle mass and respiratory health. The aim of the study was to analyze the associations of particle properties, especially size-segregated particle number concentrations (PNC), and respiratory mortality in Beijing, P.R. China. We gathered daily values of respiratory mortality and air pollution data of the Beijing urban area. Generalized additive models were used to estimate the associations. Single pollutant models showed that delayed concentrations of SO₂, total PNCs, and PNC of 300–1000 nm were adversely associated with total respiratory mortality. There was an indication that adverse health effects of PNCs might be stronger for stagnant air masses. Two-pollutant models verified the independence of associations of total PNCs of other pollutants (SO₂, NO₂, and PM₁₀). In conclusion, particle number concentrations, especially accumulation mode particles, might be factors influencing the adverse associations between particulate matter and respiratory health.     

The Po River Delta (North Italy) Indoor Epidemiological Study: Effects of Pollutant Exposure on Acute Respiratory Symptoms and Respiratory Function in Adults

The authors studied the effects of relatively low doses of nitrogen dioxide and respirable suspended particulate matter (i.e., < 2.5 μ) on acute respiratory symptoms and on peak expiratory flow in 383 adults (15–72 yr of age) who lived in the Po River Delta area, located near Venice. During 2 wk—1 wk in winter and 1 wk in summer—the authors monitored each participant's house to measure nitrogen dioxide (in parts per billion) and respirable suspended particulate (μg/m³) concentration. Information on sex, age, height, weight, daily activity patterns, active and passive smoking, chronic respiratory diseases, daily peak expiratory flow, and presence of acute respiratory symptoms during the weeks monitoring occurred were also collected. Peak expiratory flow variation was studied as mean amplitude percentage (i.e., amplitude/mean) and percentage of diurnal variation (maximum/minimum). The exposure indices to nitrogen dioxide (nitrogen dioxide-index of exposure) and to respirable suspended particulate matter (respirable suspended particulate matter-index of exposure) were computed as the product of pollutant concentration and time of exposure. The authors considered indices as “low” or “high” on the basis of the median value. The median nitrogen dioxide was 20 ppb in winter and 14 ppb in summer; the highest nitrogen dioxide levels occurred in the kitchen in the winter (33 ppb) and summer (20 ppb). The median respirable suspended particulate matter was 68 μg/m³ in winter and 45 μg/m³ in summer. Only in winter were there significant associations between bronchitic/asthmatic symptoms and “high” nitrogen dioxide and respirable suspended particulate matter indices. In subjects who did not smoke, a significant influence of the “high” respirable suspended particulate matter-index of exposure was also observed in summer. With respect to peak expiratory flow and its variability, respirable suspended particulate matter-index of exposure was associated with an increase of both amplitude/mean and maximum/mean; however, with respect to the nitrogen dioxide-index of exposure, the association was significant only in subjects with chronic respiratory diseases (i.e., asthma and bronchitis). These relationships were significant only in winter. In conclusion, the results of the current study indicate that there is an association between relatively low doses of pollutants and acute respiratory symptoms and peak expiratory flow in adults.     

Short-Term Effects of Air Pollution on Wheeze in Asthmatic Children in Fresno,California

Background

Although studies have demonstrated that air pollution is associated with exacerbation of asthma symptoms in children with asthma, little is known about the susceptibility of subgroups, particularly those with atopy.

Objective

This study was designed to evaluate our a priori hypothesis that identifiable subgroups of asthmatic children are more likely to wheeze with exposure to ambient air pollution.

Methods

A cohort of 315 children with asthma, 6–11 years of age, was recruited for longitudinal follow-up in Fresno, California (USA). During the baseline visit, children were administered a respiratory symptom questionnaire and allergen skin-prick test. Three times a year, participants completed 14-day panels during which they answered symptom questions twice daily. Ambient air quality data from a central monitoring station were used to assign exposures to the following pollutants: particulate matter ≤ 2.5 μm in aerodynamic diameter, particulate matter between 2.5 and 10 μm in aerodynamic diameter (PM_10–2.5), elemental carbon, nitrogen dioxide (NO₂), nitrate, and O₃.

Results

For the group as a whole, wheeze was significantly associated with short-term exposures to NO₂ [odds ratio (OR) = 1.10 for 8.7-ppb increase; 95% confidence interval (CI), 1.02–1.20] and PM_10–2.5 (OR = 1.11 for 14.7-μg/m³ increase; 95% CI, 1.01–1.22). The association with wheeze was stronger for these two pollutants in children who were skin-test positive to cat or common fungi and in boys with mild intermittent asthma.

Conclusion

A pollutant associated with traffic emissions, NO₂, and a pollutant with bioactive constituents, PM_10–2.5, were associated with increased risk of wheeze in asthmatic children living in Fresno, California. Children with atopy to cat or common fungi and boys with mild intermittent asthma were the subgroups for which we observed the largest associations.     

Estimated acute effects of ambient ozone and nitrogen dioxide on mortality in the Pearl River Delta of southern China

Background and objectives: Epidemiologic studies have attributed adverse health effects to air pollution; however, controversy remains regarding the relationship between ambient oxidants [ozone (O₃) and nitrogen dioxide (NO₂)] and mortality, especially in Asia. We conducted a four-city time-series study to investigate acute effects of O₃ and NO₂ in the Pearl River Delta (PRD) of southern China, using data from 2006 through 2008.Methods: We used generalized linear models with Poisson regression incorporating natural spline functions to analyze acute mortality in association with O₃ and NO₂, with PM₁₀ (particulate matter ≤ 10 μm in diameter) included as a major confounder. Effect estimates were determined for individual cities and for the four cities as a whole. We stratified the analysis according to high- and low- exposure periods for O₃.Results: We found consistent positive associations between ambient oxidants and daily mortality across the PRD cities. Overall, 10-μg/m³ increases in average O₃ and NO₂ concentrations over the previous 2 days were associated with 0.81% [95% confidence interval (CI): 0.63%, 1.00%] and 1.95% (95% CI: 1.62%, 2.29%) increases in total mortality, respectively, with stronger estimated effects for cardiovascular and respiratory mortality. After adjusting for PM₁₀, estimated effects of O₃ on total and cardiovascular mortality were stronger for exposure during high-exposure months (September through November), whereas respiratory mortality was associated with O₃ exposure during nonpeak exposure months only.Conclusions: Our findings suggest significant acute mortality effects of O₃ and NO₂ in the PRD and strengthen the rationale for further limiting the ambient pollution levels in the area.