Air pollution, weather and positive airway pressure treatment adherence in adults with sleep apnea: a retrospective community-based repeated-measures longitudinal study.

We assessed the relation between air pollution, weather, and adherence to positive airway pressure (PAP) therapy in a retrospective community-based repeated-measures study of adults with obstructive sleep apnea who purchased PAP devices from a registered provider between 2013 and 2017 (Ottawa, Ontario, Canada) and had at least one day of data. Daily PAP-derived data, air pollution, and weather databases were linked using postal code. The exposures were mean nocturnal (8:00 p.m. to 8:00 a.m.) (i) residential concentrations of nitrogen dioxide (NO2 ), fine particulate matter <=2.5 µm (PM2.5 ), ozone (O3 ), and Air Quality Health Index (AQHI), and (ii) temperature, relative humidity, and barometric pressure. Covariates in the main model were demographics, season, exposure year, and PAP therapy mode. We analysed 8148 adults (median age of 54 years and 61% men) and 2,071,588 days of data. Based on daily data, the median (interquartile range) daily PAP usage was 416 (323-487) min. Using mixed-effect regression analyses to incorporate daily data and clustering by individuals, we found a statistically significant decrease in adherence for increased levels of NO2 , PM2.5 , and AQHI. The largest effect was for NO2 : a decrease in daily PAP use while comparing the highest versus lowest quartiles (Qs) was 3.4 (95% confidence interval [CI] 2.8-3.9) min. Decreased PAP adherence was also associated with increased temperature (Q4 versus Q1: 2.6 [95% CI: 1.5-3.7] min) and decreased barometric pressure (Q1 versus Q4: 2.0 [95% CI 1.5-2.5] min). We observed modest but statistically significant acute effects of air pollution and weather on daily PAP adherence.

Global estimates of mortality associated with long-term exposure to outdoor fine particulate matter.

Exposure to ambient fine particulate matter (PM2.5) is a major global health concern. Quantitative estimates of attributable mortality are based on disease-specific hazard ratio models that incorporate risk information from multiple PM2.5 sources (outdoor and indoor air pollution from use of solid fuels and secondhand and active smoking), requiring assumptions about equivalent exposure and toxicity. We relax these contentious assumptions by constructing a PM2.5-mortality hazard ratio function based only on cohort studies of outdoor air pollution that covers the global exposure range. We modeled the shape of the association between PM2.5 and nonaccidental mortality using data from 41 cohorts from 16 countries-the Global Exposure Mortality Model (GEMM). We then constructed GEMMs for five specific causes of death examined by the global burden of disease (GBD). The GEMM predicts 8.9 million [95% confidence interval (CI): 7.5-10.3] deaths in 2015, a figure 30% larger than that predicted by the sum of deaths among the five specific causes (6.9; 95% CI: 4.9-8.5) and 120% larger than the risk function used in the GBD (4.0; 95% CI: 3.3-4.8). Differences between the GEMM and GBD risk functions are larger for a 20% reduction in concentrations, with the GEMM predicting 220% higher excess deaths. These results suggest that PM2.5 exposure may be related to additional causes of death than the five considered by the GBD and that incorporation of risk information from other, nonoutdoor, particle sources leads to underestimation of disease burden, especially at higher concentrations.

Associations between air pollution and cardio-respiratory physiological measures in older adults exercising outdoors.

We examined whether exercising indoors vs. outdoors reduced the cardio-respiratory effects of outdoor air pollution. Adults ≥55 were randomly assigned to exercise indoors when the Air Quality Health Index was ≥5 and outdoors on other days (intervention group, n = 37), or outdoors everyday (control group, n = 35). Both groups completed cardio-respiratory measurements before and after exercise for up to 10 weeks. Data were analyzed using linear mixed effect regression models. In the control group, an interquartile range increase in fine particulate matter (PM2.5) was associated with increases of 1.4% in heart rate (standard error (SE) = 0.7%) and 5.6% (SE = 2.6%) in malondialdehyde, and decreases of 5.6% (SE = 2.5%) to 16.5% (SE = 7.5%) in heart rate variability measures. While the hypothesized benefit of indoor vs. outdoor exercise could not be demonstrated due to an insufficient number of intervention days (n = 2), the study provides evidence of short-term effects of air pollution in older adults. ISRCTN #26552763.

Do acute changes in ambient air pollution increase the risk of potentially fatal cardiac arrhythmias in patients with implantable cardioverter defibrillators?

BACKGROUND: Daily changes in ambient air pollution have been associated with cardiac morbidity and mortality. Precipitating a cardiac arrhythmia in susceptible individuals may be one mechanism. We investigated the influence of daily changes in air pollution in the Province of Ontario, Canada on the frequency of discharges from implantable cardio defibrillators (ICDs) which occur in response to potentially life threatening arrhythmias. METHODS: Using a case- crossover design, we compared ambient air pollution concentrations on the day of an ICD discharge to other days in the same month and year in 1952 patients. We adjusted for weather, lagged the exposure data from 0 to 3 days, and stratified the results by several patient-related characteristics. RESULTS: Median (interquartile range) for ozone (O3), fine particulate matter (PM2.5), sulphur dioxide (SO2) and nitrogen dioxide (NO2) were 26.0 ppb (19.4, 33.0), 6.6 µg/m3 (4.3, 10.6), 1.00 ppb (0.4,2.1), 10.0 ppb (6.0,15.3) respectively. Unlagged odds ratios (95%) for an ICD discharge associated with an interquartile range increase in pollutant were 0.97 (0.86, 1.09) for O3, 0.99 (0.92, 1.06) for PM2.5, 0.97 (0.91, 1.03) for SO2, and 1.00 (0.89, 1.12) for NO2. CONCLUSION: We found no evidence that the concentrations of ambient air pollution observed in our study were a risk factor for potentially fatal cardiac arrhythmias in patients with ICDs.

Air pollution and emergency department visits for respiratory diseases: A multi-city case crossover study.

Increasing evidence suggests that ambient air pollution is a major risk factor for both acute and chronic respiratory disease exacerbations and emergencies. The objective of this study was to determine the association between ambient air pollutants and emergency department (ED) visits for respiratory conditions in nine districts across the province of Ontario in Canada. Health, air pollutant (PM2.5, NO2, O3, and SO2), and meteorological data were retrieved from April 2004 to December 2011. Respiratory diseases were categorized as: chronic obstructive pulmonary disease (COPD, including bronchiectasis) and acute upper respiratory diseases. A case-crossover design was used to test the associations between ED visits and ambient air pollutants, stratified by sex and season. For COPD among males, positive results were observed for NO2 with lags of 3-6 days, for PM2.5 with lags 1-8, and for SO2 with lags of 4-8 days. For COPD among females, positive results were observed for O3 with lags 2-4 days, and for SO2 among lags of 3-6 days. For upper respiratory disease emergencies among males, positive results were observed for NO2 (lags 5-8 days), for O3, (lags 0-6 days), PM2.5 (all lags), and SO2 (lag 8), and among females, positive results were observed for NO2 for lag 8 days, for O3, PM2.5 among all lags. Our study provides evidence of the associations between short-term exposure to air pollution and increased risk of ED visits for upper and lower respiratory diseases in an environment where air pollutant concentrations are relatively low.

Concentration-Response Functions as an Essence of the Results from Lags.

Among various aspects of environmental epidemiology, one is to assess the relationships between ambient air pollution and health outcomes. The goal of this work is to estimate the associations in the form of the parametric concentration-response functions (C-RF). Various forms of the C-RFs are proposed in this short-term health effect study. Emergency department (ED) visits for all respiratory health problems are analyzed as an illustrative example. A case-crossover (CC) technique is applied as a study design. Daily cases are organized as daily counts by the same day of the week in one common month. A conditional Poisson regression is used in the constructed statistical models. Temperature and relative humidity are included in the statistical models in the form of natural splines. Ground-level ozone concentration is considered an exposure. Ozone concentration values are transformed and submitted to the statistical models. The parameters of the transformation are determined by using the goodness of fit criterion. Counts of ED visits are analyzed in relation to a sequence of lagged exposure to ozone. The C-RF shapes are constructed for each individual lag. In a final step, the set of the estimated C-RF shapes is used to create a pooled C-RF shape. The results are positive and statistically significant for nine lagged exposures, from 0 to 8 days. The following relative risks (RR) were estimated from the constructed C-RFs at 30 ppb concentration of ozone: RR = 1.0531 (95% confidence interval: 1.0231, 1.0718), 1.0462 (1.0253, 1.0677), and 1.0387, (1.0240, 1.0531), realizing the CC method, CC method + transformation, and CC method + flexible transformation, respectively. The pooled C-RF shape gives a summary of the associations between ED visits for respiratory conditions and ambient ozone. The estimated shapes indicate lower air health effects than the standard CC methods. Among three considered statistical models, the CC method + flexible transformation is the most appropriate to use according to the goodness of fit criterion.

Urban air pollution and emergency department visits related to central nervous system diseases.

Ambient air pollution has been associated with adverse neurological health outcomes. Ambient pollutants are thought to trigger oxidative stress and inflammation to which vulnerable populations, such as elderly may be particularly susceptible. Our study investigated the possible association between concentrations of ambient air pollutants and the number of emergency department (ED) visits for nervous system disorders among people residing in a large Canadian city. A time-stratified case-crossover study design combining data from the National Ambulatory Care Reporting System (NACRS) and the National Air Pollution Surveillance (NAPS) between 2004 and 2015 was used. Two air quality health indices were considered in additional to specific pollutants, including carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3) and fine particulate matter (PM2.5). Weather condition data were included in the models. ED visits with a discharge diagnosis were identified using ICD-10 codes (G00-G99). The analysis was stratified by sex and age, also by seasons. The associations were investigated in arrays organized as 18 strata and 15 time lags (in days) for each pollutant. Overall, 140,511 ED visits were included for the analysis. Most ED visits were related to episodic and paroxysmal diagnoses (G40-G47, 64%), with a majority of visits for migraines (G43, 39%). Among females, an increase of 0.1ppm ambient CO was associated with an increased risk of paroxysmal diagnoses at day 1 (RR = 1.019 (95%CI 1.004-1.033)), day 6 (1.024 (1.010-1.039)) and day 7 (1.022 (1.007-1.036). PM2.5 and SO2, and air quality indices were similarly associated with ED visits for episodic and paroxysmal disorders in days 6 and 7. Findings highlight that ambient air pollution is associated with an increased number of ED visits for nervous system disorders, particularly visits for paroxysmal diagnoses.

Urban Air Pollution and Emergency Department Visits for Neoplasms and Outcomes of Blood Forming and Metabolic Systems.

This study focused on investigating possible associations between exposure to urban air pollution and the number of emergency department (ED) visits for various health outcomes. The outcomes were grouped into four chapters of the International Classification of Diseases Tenth Revision (ICD-10) system (i.e., Chapter II-IV: "Neoplasms", "Diseases of the blood", "Endocrine, nutritional and metabolic diseases", and XVIII: "Symptoms, signs and abnormal clinical and laboratory findings"). The data were collected for the city of Toronto, Canada, (2004-2015, 4292 days). Four gaseous air pollutants (carbon monoxide (CO), nitrogen dioxide (NO2), ground level ozone (O3), and sulfur dioxide (SO2)) and fine particulate matter (PM2.5), and two calculated air quality health indexes (AQHI) based on Toronto were used. The statistical models were constructed by applying the conditional Poisson regression. The exposure was assessed over a maximum of 15 days (time lags 0-14 days). An analysis was performed with the following strata: sex, age, and seasons. Relative risks (RR) and their 95% confidence intervals (95%CI) were estimated for an increase in concentration by a one interquartile range (IQR). For the AQHI (composed of NO2, O3, and PM2.5), IQR = 1, the estimations for lag 1 and all patients, are RR = 1.023 (95%CI: 1.008, 1.038), 1.026 (1.012, 1.040), 1.013 (1.003, 1.024), and 1.007 (1.003, 1.010) for Chapters II-IV and XVIII, respectively. The results show that in the four large, analyzed health groups, the impact of air quality mainly occurs over a short period (from current day to a maximum of 3 days after exposure).

Air Pollution and the Effectiveness of Positive Airway Pressure Therapy in Individuals With Sleep Apnea: A Retrospective Community-Based Repeated-Measures Longitudinal Study.

BACKGROUND: Ambient air pollution may affect the severity of untreated OSA, but it is unknown whether air pollution adversely impacts the effectiveness of positive airway pressure (PAP) therapy. RESEARCH QUESTION: Do short-term changes in outdoor air pollution adversely impact adults with OSA using PAP therapy? STUDY DESIGN AND METHODS: We conducted a retrospective community-based repeated-measures longitudinal study of adults with OSA who purchased a PAP device from a registered equipment provider between 2013 and 2017 (Ontario, Canada) and had data on the daily device-derived residual apnea-hypopnea index (AHIFlow). We linked daily PAP-derived data to air pollution databases using postal codes. The primary exposures were mean nocturnal (8 pm to 8 am) residential concentrations of ozone, fine particulate matter, nitrogen dioxide, carbon monoxide, sulfur dioxide, and the Air Quality Health Index (AQHI). Potential confounders considered were demographics, season and year of exposure, initial OSA severity, other PAP parameters, and climate-related variables. RESULTS: Eight thousand one hundred forty-eight adults were analyzed with a median of 89 days (interquartile range [IQR], 29-302 days) of observation during which PAP was used for ≥ 4 h. The median daily AHIFlow was 1.2/h (IQR, 0.5-2.5/h). In mixed multivariate regression analyses, an increase in air pollution was associated with a statistically significant increase in AHIFlow for most statistical models. The largest effect was for the AQHI: an increase in AHIFlow while comparing highest vs lowest quartiles was 0.07/h (95% CI, 0.05-0.10/h). INTERPRETATION: We demonstrated a modest but statistically significant increase in residual respiratory events during PAP therapy associated with an increase in air pollution concentrations.

Ambient air pollution and emergency department visits in Toronto, Canada.

To investigate the acute impact of various air pollutants on various disease groups in the urban area of the city of Toronto, Canada. Statistical models were developed to estimate the relative risk of an emergency department visit associated with ambient air pollution concentration levels. These models were generated for 8 air pollutants (lagged from 0 to 14 days) and for 18 strata (based on sex, age group, and season). Twelve disease groups extracted from the International Classification of Diseases 10th Revision (ICD-10) were used as health classifications in the models. The qualitative results were collected in matrices composed of 18 rows (strata) and 15 columns (lags) for each air pollutant and the 12 health classifications. The matrix cells were assigned a value of 1 if the association was positively statistically significant; otherwise, they were assigned to a value of 0. The constructed matrices were totalized separately for each air pollutant. The resulting matrices show qualitative associations for grouped diseases, air pollutants, and their corresponding lagged concentrations and indicate the frequency of statistically significant positive associations. The results are presented in colour-gradient matrices with the number of associations for every combination of patient strata, pollutant, and lag in corresponding cells. The highest number of the associations was 8 (of 12 possible) obtained for the same day exposure to carbon monoxide, nitrogen dioxide, and days with elevated air quality health index (AQHI) values. For carbon monoxide, the number of the associations decreases with the increasing lags. For this air pollutant, there were almost no associations after 8 days of lag. In the case of nitrogen dioxide, the associations persist even for longer lags. The numerical values obtained from the models are provided for every pollutant. The constructed matrices are a useful tool to analyze the impact of ambient air pollution concentrations on public health.

Air Pollution and Emergency Department Visits for Disease of the Genitourinary System.

The aim of this study is to determine associations between ambient air pollution and the number of emergency department (ED) visits for diseases of the genitourinary tract in Toronto, Canada. We used the National Ambulatory Care Reporting System (NACRS) database to obtain the related ED visits and developed statistical models using daily data on ED visits, temperature, relative humidity, and outdoor air pollution concentration levels. The NACRS database contains data on hospital-based and community-based ambulatory care. The environmental data were retrieved from the National Air Pollution Surveillance (NAPS) program. The NAPS is the main source of ambient air quality data in Canada. We considered 2 air quality health indexes and 6 air pollutants: daily means of fine particulate matter PM2.5, O3, CO, NO2, SO2, and also maximum 8-hour average ozone. For every air pollutant, we fit 270 models (15 lags × 18 strata). We found that same-day air pollution concentrations have the highest number of statistically significantly positive associations with ED visits for genitourinary health outcomes. A total of 133 positive associations were identified over the 14 days lag. In subgroup (strata) analysis, females older than 60 years of age were found to have the most positive associations. In particular, nitrogen dioxide was found to be highly associated with ED visits for females over 60; an increase in NO2 was associated with an increased relative risk (RR) of ED visits when lagged over 0, 1, and 2 days (RR = 1.040 [95% confidence interval: 1.028, 1.052], 1.020 [1.009, 1.032], and 1.025 [1.013, 1.036], respectively). The values of risks are reported for a 1 interquartile range increase in concentration (8.8 ppb). Our results suggest that urban ambient air pollution affect the number of ED visits due to genitourinary system conditions.

Air pollution and emergency department visits for chest pain and weakness in Edmonton, Canada.

OBJECTIVES: Chest pain or weakness can be first signal of health problems. Many studies demonstrate that these conditions can be related to air pollution. This work uses time-series data to investigate the association. MATERIAL AND METHODS: This is a study of 68,714 emergency department (ED) visits for chest pain (ICD-9: 786) and of 66,092 ED visits for weakness (ICD-9: 780). The hierarchical method was applied to analyse the associations between daily counts of ED visits for chest pain and weakness (separately) and the levels of the air pollutants and meteorological variables. The counts of visits for all patients, males and females were analysed separately by whole period (I-XII), warm (IV-IX) and cold (X-III). RESULTS: The results are presented in the form of the excess risks associated with an increase in the interquartile range (IQR) for the pollutant. Chest pain: 2.4% (95% CI: 1.0-3.9) for CO, females, I-XII; 3.8% (95% CI: 0.0-7.8) for NO(2), males, IV-IX; 4.5% (95% CI: 0.9-8.3) for O(3) (1-day lagged), males, IV-IX; 2.8% (95% CI: 0.5-5.2), for PM(10), males, X-III; 2.0% (95% CI: 0.0-4.0), for SO(2), females, X-III; 2.1% (95% CI: 0.2-4.0) for PM(2.5), all, X-III. Weakness: 2.1% (95% CI: 0.4-3.7) for CO (2-day lagged), males, X-III; 3.4% (95% CI: 1.0-5.9) for NO(2) (2-day lagged), males, X-III; 2.4% (95% CI: 0.9-3.9) for SO(2), females, I-XII; 4.6% (95% CI: 1.0-8.2) for O(3) (1-day lagged), females, IV-IX. CONCLUSIONS: Obtained findings provide support for the hypothesis that ED visits for chest pain and weakness are associated with exposure to ambient air pollution.

Air Pollution and Emergency Department Visits for Mental Disorders among Youth.

Although exposure to ambient air pollution has been linked to mental health problems, little is known about its potential effects on youth. This study investigates the association between short-term exposure to air pollutants and emergency department (ED) visits for mental health disorders. The National Ambulatory Care Reporting System database was used to retrieve ED visits for young individuals aged 8-24 years in Toronto, Canada. Daily average concentrations of nitrogen dioxide (NO2), fine particulate matter (PM2.5), and daily maximum 8 h ozone (O3) were calculated using measurement data from seven fixed stations. A case-crossover (CC) design was implemented to estimate the associations between ED visits and air pollution concentrations. Mental health ED visits were identified using International Classification of Diseases 10th Revision (ICD-10) codes, with seven categories considered. Models incorporating air pollutants and ambient temperature (with lags of 0-5 days) using a time-stratified CC technique were applied. Multivariable regression was performed by sex, three age groups, and seven types of mental health disorders to calculate relative risk (RR). The RRs were reported for one interquartile range (IQR) change in the air pollutant concentrations. Between April 2004 and December 2015 (4292 days), there were 83,985 ED visits for mental-health related problems in the target population. Several exposures to air pollutants were shown to have associations with ED visits for mental health including same day exposure to fine particulate matter (IQR = 6.03 µg/m3, RR = 1.01 (95% confidence interval: 1.00-1.02), RR = 1.02 (1.00-1.03)) for all and female-only patients, respectively. One-day lagged exposure was also associated with ED visits for PM2.5 (RR = 1.02 (1.01-1.03)), for nitrogen dioxide (IQR = 9.1 ppb, RR = 1.02 (1.00-1.04)), and ozone (IQR = 16.0 ppb, RR = 1.06 (1.01-1.10)) for males. In this study, urban air pollution concentration-mainly fine particulate matter and nitrogen dioxide-is associated with an increased risk for ED visits for adolescents and young adults with diagnosed mental health disorders.

Effect of ambient air pollution on the incidence of appendicitis.

BACKGROUND: The pathogenesis of appendicitis is unclear. We evaluated whether exposure to air pollution was associated with an increased incidence of appendicitis. METHODS: We identified 5191 adults who had been admitted to hospital with appendicitis between Apr. 1, 1999, and Dec. 31, 2006. The air pollutants studied were ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide, and suspended particulate matter of less than 10 micro and less than 2.5 micro in diameter. We estimated the odds of appendicitis relative to short-term increases in concentrations of selected pollutants, alone and in combination, after controlling for temperature and relative humidity as well as the effects of age, sex and season. RESULTS: An increase in the interquartile range of the 5-day average of ozone was associated with appendicitis (odds ratio [OR] 1.14, 95% confidence interval [CI] 1.03-1.25). In summer (July-August), the effects were most pronounced for ozone (OR 1.32, 95% CI 1.10-1.57), sulfur dioxide (OR 1.30, 95% CI 1.03-1.63), nitrogen dioxide (OR 1.76, 95% CI 1.20-2.58), carbon monoxide (OR 1.35, 95% CI 1.01-1.80) and particulate matter less than 10 micro in diameter (OR 1.20, 95% CI 1.05-1.38). We observed a significant effect of the air pollutants in the summer months among men but not among women (e.g., OR for increase in the 5-day average of nitrogen dioxide 2.05, 95% CI 1.21-3.47, among men and 1.48, 95% CI 0.85-2.59, among women). The double-pollutant model of exposure to ozone and nitrogen dioxide in the summer months was associated with attenuation of the effects of ozone (OR 1.22, 95% CI 1.01-1.48) and nitrogen dioxide (OR 1.48, 95% CI 0.97-2.24). INTERPRETATION: Our findings suggest that some cases of appendicitis may be triggered by short-term exposure to air pollution. If these findings are confirmed, measures to improve air quality may help to decrease rates of appendicitis.

Air pollution and emergency department visits for cardiac and respiratory conditions: a multi-city time-series analysis.

BACKGROUND: Relatively few studies have been conducted of the association between air pollution and emergency department (ED) visits, and most of these have been based on a small number of visits, for a limited number of health conditions and pollutants, and only daily measures of exposure and response. METHODS: A time-series analysis was conducted on nearly 400,000 ED visits to 14 hospitals in seven Canadian cities during the 1990 s and early 2000s. Associations were examined between carbon monoxide (CO), nitrogen dioxide (NO2), ozone (O3), sulfur dioxide (SO2), and particulate matter (PM 10 and PM2.5), and visits for angina/myocardial infarction, heart failure, dysrhythmia/conduction disturbance, asthma, chronic obstructive pulmonary disease (COPD), and respiratory infections. Daily and 3-hourly visit counts were modeled as quasi-Poisson and analyses controlled for effects of temporal cycles, weather, day of week and holidays. RESULTS: 24-hour average concentrations of CO and NO2 lag 0 days exhibited the most consistent associations with cardiac conditions (2.1% (95% CI, 0.0-4.2%) and 2.6% (95% CI, 0.2-5.0%) increase in visits for myocardial infarction/angina per 0.7 ppm CO and 18.4 ppb NO2 respectively; 3.8% (95% CI, 0.7-6.9%) and 4.7% (95% CI, 1.2-8.4%) increase in visits for heart failure). Ozone (lag 2 days) was most consistently associated with respiratory visits (3.2% (95% CI, 0.3-6.2%), and 3.7% (95% CI, -0.5-7.9%) increases in asthma and COPD visits respectively per 18.4 ppb). Associations tended to be of greater magnitude during the warm season (April - September). In particular, the associations of PM 10 and PM2.5 with asthma visits were respectively nearly three- and over fourfold larger vs. all year analyses (14.4% increase in visits, 95% CI, 0.2-30.7, per 20.6 microg/m3 PM 10 and 7.6% increase in visits, 95% CI, 5.1-10.1, per 8.2 microg/m3 PM2.5). No consistent associations were observed between three hour average pollutant concentrations and same-day three hour averages of ED visits. CONCLUSION: In this large multicenter analysis, daily average concentrations of CO and NO2 exhibited the most consistent associations with ED visits for cardiac conditions, while ozone exhibited the most consistent associations with visits for respiratory conditions. PM 10 and PM2.5 were strongly associated with asthma visits during the warm season.

Air pollution and ED visits for chest pain.

This was a study of 157,028 emergency department (ED)-diagnosed visits for chest pain (International Classification of Diseases, Ninth Revision [ICD-9]: 786) in 6 cities in Canada. The generalized linear mixed methods technique was applied to analyze the relations between daily counts of ED visits for chest pain on the levels of ambient air pollutants after adjusting for meteorological variables. The daily counts of visits were analyzed separately for the whole period (January-December), warm (April-September), and cold (October-March). The results are presented in the form of the excess risks associated with an increase in the mean values of the pollutant concentrations. The highest increase was obtained for nitrogen dioxide (NO2) exposure in the warm period as follows: 5.9% (95% confidence interval, 3.3-5.8) for mean value equals to 20.1 ppb. The associations of ED visits for chest pain with air pollution are very similar to the associations of ED visits related to cardiac problems.

Air pollution and daily ED visits for migraine and headache in Edmonton, Canada.

BACKGROUND: A variety of environmental factors have been identified as possible triggers for migraine and other headache syndromes. OBJECTIVE: We analyzed associations between air pollution and emergency department (ED) visits for migraine and headache. METHODS: Analysis was based on 56,241 ED visits for migraine and 48,022 ED visits for headache to Edmonton hospitals between 1992 and 2002. A Poisson model of counts hierarchically clustered by day of week, month, and year was applied using generalized linear mixed models. Temperature and relative humidity were included as covariates. RESULTS: Females accounted for 78.5% of migraine visits and 56.3% of headache visits. An interquartile range (IQR) increase (6.2 microg/m3) in daily average particulate matter of median aerodynamic diameter less than 2.5 microm (PM2.5) was associated with increases in visits of 3.3% for migraine (95% confidence interval [CI]: 0.6-6.0), lagged 2 days, and 3.4% for headache (95% CI: 0.3-6.6), lagged 0 days, among females in the cold season (October-March). PM2.5 was also associated with cold season migraine visits among females at lag 0 and 1 day (P < .1). In the warm period (April-September), a 2.3-ppb IQR increase in sulfur dioxide was associated with a 2.5% increase in migraine visits (95% CI: 0.3-4.6) among females, whereas a 12.8-ppb IQR increment in nitrogen dioxide was associated with a 6.8% increase in headache visits (95% CI: 1.5-12.5) for males. CONCLUSIONS: Findings provide preliminary evidence of an association between air pollution and ED visits for migraine and nonspecific headache. Findings were most consistent for particulate matter.

Air pollution and daily emergency department visits for depression.

OBJECTIVES: To investigate the potential correlation between ambient air pollution exposure and emergency department (ED) visits for depression. MATERIALS AND METHODS: A hierarchical clusters design was used to study 27 047 ED visits for depression in six cities in Canada. The data used in the analysis contain the dates of visits, daily numbers of diagnosed visits, and daily mean concentrations of air pollutants as well as the meteorological factors. The generalized linear mixed models technique was applied to data analysis. Poisson models were fitted to the clustered counts of ED visits with a single air pollutant, temperature and relative humidity. RESULTS: Statistically significant positive correlations were observed between the number of ED visits for depression and the air concentrations of carbon monoxide (CO), nitrogen dioxide (NO2), sulphur dioxide (SO2) and particulate matter (PM10). The percentage increase in daily ED visits was 15.5% (95% CI: 8.0-23.5) for CO per 0.8 ppm and 20.0% (95% CI: 13.3-27.2) for NO2 per 20.1 ppb, for same day exposure in the warm weather period (April-September). For PM10, the largest increase, 7.2% (95% CI: 3.0-11.6) per 19.4 ug/m3, was observed for the cold weather period (October-March). CONCLUSIONS: The results support the hypothesis that ED visits for depressive disorder correlate with ambient air pollution, and that a large majority of this pollution results from combustion of fossil fuels (e.g. in motor vehicles).

Ambient sulphur dioxide exposure and emergency department visits for migraine in Vancouver, Canada.

OBJECTIVES: Ambient exposure to sulphur dioxide (SO2) has been previously associated with emergency department (ED) visits for migraine headaches. In the present study, the objective was to examine the relationship between ED visits for migraine and ambient sulphur dioxide concentrations. DESIGN AND METHODS: This was a time-series study of 1059 ED visits for migraine (ICD-9: 346) recorded at a Vancouver hospital between 1999 and 2003 (1 520 days). Air pollution levels of SO2 were measured by fixed-site monitoring stations. The generalized linear mixed models technique was applied to regress daily counts of ED visits for migraine on the levels of the pollutant after adjusting for meteorological conditions: temperature and relative humidity. The analysis was stratified by season and gender. RESULTS: Positive and statistically significant correlations were observed for SO2 exposure and ED visits for migraine for females during colder months (October-March). The percentage increase in daily visits was 16.8% (95% CI: 1.2-34.8) for a 4-day average (of daily mean concentrations) SO2 level, for an interquartile range (IQR) increase of 1.9 ppb. CONCLUSIONS: Our findings provide additional support for a consistent correlation between migraine headache and air pollution (SO2).

Emergency department visits for migraine and headache: a multi-city study.

OBJECTIVES: We set out to examine associations between ambient air pollution concentrations and emergency department (ED) visits for migraine/headache in a multi-city study. MATERIALS AND METHODS: We designed a time-series study of 64 839 ED visits for migraine (ICD-9: 346) and of 68 495 ED visits for headache (ICD-9: 784) recorded at hospitals in five different cities in Canada. The data (days) were clustered according to the hierarchical structure (location, year, month, day of week). The generalised linear mixed models technique was applied to fit the logarithm of clustered daily counts of ED visits for migraine, and separately for headache, on the levels of air pollutants, after adjusting for meteorological conditions. The analysis was performed by sex (all, male, female) and for three different seasonal periods: whole (January-December), warm (April-September), and cold (October-March). RESULTS: For female ED visits for migraine, positive associations were observed during the warm season for sulphur dioxide (SO2), and in the cold season for particulate matter (PM2.5) exposures lagged by 2-days. The percentage increase in daily visits was 4.0% (95% CI: 0.8-7.3) for SO2 mean level change of 4.6 ppb, and 4.6% (95% CI: 1.2,-8.1) for PM2.5 mean level change of 8.3 microg/m3. For male ED visits for headache, the largest association was obtained during the warm season for nitrogen dioxide (NO2), which was 13.5% (95% CI: 6.7-20.7) for same day exposure. CONCLUSIONS: Our findings support the associations between air pollutants and the number of ED visits for headache.