Gaseous air pollutants and hospitalization for respiratory disease in the neonatal period.OBJECTIVE: Current levels of ambient air pollution are associated with morbidity and mortality Morbidity and Mortality can refer to:
n. A poisonous brown gas, NO2, often found in smog and automobile exhaust fumes and synthesized for use as a nitrating agent, a catalyst, and an oxidizing agent. Noun 1. , in 11 large Canadian cities. STUDY DESIGN: Daily time-series analyses were employed and results were adjusted for day of the week, temperature, barometric pressure, and relative humidity relative humidity n. The ratio of the amount of water vapor in the air at a specific temperature to the maximum amount that the air could hold at that temperature, expressed as a percentage. . RESULTS: The percent increases in hospitalization associated with an increase in air pollution equivalent to its interquartile range In descriptive statistics, the interquartile range (IQR), also called the midspread, middle fifty and middle of the #s, is a measure of statistical dispersion, being equal to the difference between the third and first quartiles. were 3.35 [95% confidence interval confidence interval, n a statistical device used to determine the range within which an acceptable datum would fall. Confidence intervals are usually expressed in percentages, typically 95% or 99%. (CI), 1.73-4.77] for [O.sub.3], 2.85 (95% CI, 1.68-4.02) for N[O.sub.2], 1.66 (95% CI, 0.63-2.69) for S[O.sub.2], and 1.75 (95% CI, 0.48-3.02) for CO. The independent effect of all pollutants combined was 9.61% (95% CI, 4.52-14.7%). CONCLUSION: Our results suggest that neonates are experiencing adverse effects of air pollution at current levels in Canada, and that accounts for a significant proportion of hospitalizations in this subgroup. KEY WORDS: carbon monoxide, hospital admission, infants, ozone, sulfur dioxide. Environ Health Perspect 114:1751-1754 (2006). doi:10.1289/ehp.9044 available via http://dx.doi.org/ [Online 3 August 2006] ********** Current levels of ambient air pollution in the Americas, Europe, and Australia have been associated with increased respiratory and cardiac morbidity and mortality in the general population (Bascom et al. 1996; Dockery and Pope 2002; Morgan et al. 1998). The primary focus has usually been either adults or children of all ages combined, but research is needed to know whether the results are generalizable to more narrowly defined age groups which have special characteristics. Associations between ambient air pollution and pregnancy outcomes, including preterm preterm /pre·term/ (-term´) before completion of the full term; said of pregnancy or of an infant. pre·term adj. birth, low birth weight, and intrauterine growth restriction intrauterine growth restriction n. See intrauterine growth retardation. intrauterine growth retardation Fetal growth restriction Neonatology A generic term for any delay in achieving intrauterine developmental (IUGR IUGR intrauterine growth retardation (or restriction). IUGR abbr. intrauterine growth retardation IUGR Intrauterine growth retardation, see there ), have been studied in several countries (Ritz et al. 2002; Wang et al. 1997). Liu et al. (2003) found that maternal exposure to increased concentration of gaseous air pollutants, sulfur dioxide, nitrogen dioxide, and carbon monoxide during pregnancy were positively associated with preterm birth and IUGR. The number of SIDS SIDS sudden infant death syndrome. SIDS abbr. sudden infant death syndrome SIDS, n See syndrome, sudden infant death. (sudden infant death syndrome sudden infant death syndrome (SIDS) or crib death, sudden, unexpected, and unexplained death of an apparently healthy infant under one year of age (usually between two weeks and eight months old). ) deaths increased on days of high gaseous air pollution in Canada (Dales et al. 2004). Neonates, 0-28 days of age, have a unique spectrum of morbidity including clinical presentations such as "acute life-threatening events" and "respiratory distress syndrome respiratory distress syndrome or hyaline membrane disease Common complication in newborns, especially after premature birth. Symptoms include very laboured breathing, bluish skin tinge, and low blood oxygen levels. ." To understand better the contribution of pollution to neonatal morbidity, we used time-series studies to test the hypothesis that gaseous air pollutants are associated with hospital admissions for respiratory diseases among neonates in 11 large Canadian cities. We compared hospitalization rates on higher and lower air pollution days for the same population. As stated by Peng et al. (2006) the results from multicity time-series studies are robust against alternative methodologies for confounding confounding when the effects of two, or more, processes on results cannot be separated, the results are said to be confounded, a cause of bias in disease studies. confounding factor adjustment. To bias the results, a variable would need to be associated with daily changes in air pollution and also be a risk factor for neonatal hospitalization for asthma, making confounding unlikely. Methods The study population. The study population was all emergency admissions to hospital for respiratory disease in patients from birth to the age of 27 days between 1 January 1986 and 31 December 2000 in 11 of the largest Canadian cities from the Atlantic to Pacific coasts: Calgary, Edmonton, Halifax, London, Hamilton, Ottawa, Saint John Saint John, city, Canada Saint John, city (1991 pop. 74,969), S N.B., Canada, at the mouth of the St. John River on the Bay of Fundy. A major year-round port, it has an excellent harbor, large dry docks, and terminal facilities and maintains extensive , Toronto, Vancouver, Windsor, and Winnipeg. The hospitalization data were provided by the Canadian Institute for Health Information The Canadian Institute for Health Information (CIHI) is an independent, not-for-profit organization in Canada, primarily funded by the provincial and federal governments of Canada. (http://secure.cihi.ca/cihiweb/splash.html), which collects information on all urgent and emergency admissions in Canada; the availability of this information is made possible by the fact that acute care general medical hospitals in Canada This is a list of hospitals in Canada. Alberta
respiratory disease, respiratory illness adult respiratory distress syndrome, ARDS, wet lung, white lung - acute lung injury characterized by coughing and rales; inflammation of the described by the International Classification of Disease, 9th Revision (ICD-9; World Health Organization 1975) code: asphyxia asphyxia (ăsfĭk`sēə), deficiency of oxygen and excess of carbon dioxide in the blood and body tissues. Asphyxia, often referred to as suffocation, usually results from an interruption of breathing due to mechanical blockage of the (799.0), respiratory failure Respiratory Failure Definition Respiratory failure is nearly any condition that affects breathing function or the lungs themselves and can result in failure of the lungs to function properly. (799.1), dyspnea dyspnea /dysp·nea/ (disp-ne´ah) labored or difficult breathing.dyspne´ic paroxysmal nocturnal dyspnea and respiratory abnormalities (786.0), respiratory distress syndrome (769), unspecified birth asphyxia in live-born infant (768.9), other respiratory problems after birth (770.8), and pneumonia (486). Meteorologic me·te·or·ol·o·gy n. The science that deals with the phenomena of the atmosphere, especially weather and weather conditions. [French météorologie, from Greek and air pollution data. For each city, the following daily data were provided by Environment Canada Environment Canada (EC), legally incorporated as the Department of the Environment under the Department of the Environment Act ( R.S., 1985, c. E-10 ), is the department of the Government of Canada with responsibility for coordinating environmental policies and and the National Air Pollution Monitoring System (http://www.mb.ec.gc.ca/index.en.html): mean, maximum, and minimum temperature; mean relative humidity; maximum 24-hr change in barometric pressure; and daily measurements of S[O.sub.2], N[O.sub.2], CO, and ozone throughout the 15-year study period. Most cities had several monitoring stations. Averaging data over all monitors within each city created daily summary pollution exposure measures. Daily average values for N[O.sub.2], S[O.sub.2], CO, and [O.sub.3] were used in our analysis. Twenty-four-hour averaged particulate matter particulate matter n. Abbr. PM Material suspended in the air in the form of minute solid particles or liquid droplets, especially when considered as an atmospheric pollutant. Noun 1. < 10 [micro]m in median aerodynamic diameter Drug particles for pulmonary delivery are typically characterized by aerodynamic diameter rather than geometric diameter. The velocity at which the drug settles is proportional to the aerodynamic diameter, da. (P[M.sub.10]) and sulfates (S[O.sub.4]) were measured every sixth day. Statistical Methods The air pollution, neonatal respiratory hospital admission, and weather variables, measured over the course of the study, were each expressed as a time series. We correlated daily variations in the number of neonatal hospitalization with daily variations in ambient concentrations of air pollutants by using a random-effects regression model for count data (Burnett et al. 1997). Because the response of interest is counts, the residual variation was assumed to be proportional to the expected response, accommodating overdispersion or underdispersion relative to Poisson variation. Neonatal respiratory admissions, air pollution, and weather can vary seasonally and may have other unexplained time trends that can cause confounding (Peng et al. 2006). We adjusted for temporal trends in neonatal respiratory admissions, including day of the week, and effects of weather on neonatal respiratory admissions using piecewise constant functions that varied by 30, 90, 180, 270, and 365 days throughout the study period. This approach, used to address the low counts of neonatal respiratory admissions in some cities, has been previously used by Dales et al. (2004) to study SIDS. We then selected a model with time period that either minimized the Akaike Information Criterion Akaike's information criterion, developed by Hirotsugu Akaike under the name of "an information criterion" (AIC) in 1971 and proposed in Akaike (1974), is a measure of the goodness of fit of an estimated statistical model. It is grounded in the concept of entropy. (AIC AIC Association des Infermières Canadiennes. ; Akaike 1973), or maximized the evidence that the model residuals did not display any type of structure, including serial correlation serial correlation The relationship that one event has to a series of past events. In technical analysis, serial correlation is used to test whether various chart formations are useful in projecting a security's future price movements. , using Bartlett's test Bartlett's test (Snedecor and Cochran, 1983) is used to test if k samples have equal variances. Equal variances across samples is called homoscedasticity or homogeneity of variances. . We examined serial correlation structure in the residuals after fitting models with functions that were constant over time intervals. The above steps were implemented separately for each city. Using S-PLUS (version 6.2; Insightful, Seattle, WA, USA), we tested the association between weather and respiratory admissions with a nonlinear model and natural spline In computer graphics, a smooth curve that runs through a series of given points. The term is often used to refer to any curve, because long before computers, a spline was a flat, pliable strip of wood or metal that was bent into a desired shape for drawing curves on paper. See Bezier and B-spline. functions of weather variables to remove unwanted temporal trends. These variables included daily minimum and maximum temperature, mean daily temperature, 24-hr change in barometric pressure, and mean relative humidity. Three lags (0, 1, and 2 days) were examined for each of these weather variables. The model containing the latter three weather variables minimized the AIC and was selected as the predictive weather model for daily neonatal respiratory hospitalization. Finally, air pollutants, with lags, were added to the model containing weather variables. We tested time lags between daily pollution concentration and daily neonatal respiratory admissions of 0-5 days. Results for the lag associated with the largest T ratio--the ratio of percentage increase in admissions to the standard error. Once the final model was selected, the percent change in daily hospitalization and the accompanying standard errors in relative risks were generated for each city. The results for each city were pooled. We calculated the estimates of the pooled effect size mean [+ or -] SE by using a fixed- or random-effects model. This weights the individual city effects by the inverse of the between and within-city variance. We used a random-effects model whenever the between-city variance was > 0, even if the heterogeneity among effect-size estimates for individual cities was not statistically significant. We assessed the presence of statistical heterogeneity in effect size between cities using the chi-square statistic. Pooled estimates were expressed as the percentage increase in neonatal hospitalization associated with an increase in the concentration of air pollutants equivalent to the interquartile range among all cities (Burnett et al. 1995). As stated by Peng et al. (2006), the results from multicity time-series studies are robust against alternative methodologies for confounding adjustment. To bias the results, a variable would need to be associated with daily changes in air pollution and also be a risk factor for neonatal hospitalization for asthma, making confounding unlikely. Results The frequency of occurrence of the ICD ICD International Classification of Diseases (of the World Health Organization); intrauterine contraceptive device. ICD abbr. codes used in this study, presented in Table 1, was relatively low over the 15-year period of observation, with respiratory distress syndrome being the most common of the respiratory diagnoses studied and asphyxia the least common. Details on population size and the mean of air pollution and meteorologic data are presented in Table 2. [O.sub.3] concentrations ranged from 13.3 ppb in Vancouver to 23.1 ppb in Saint John, with a population-weighted average of 17.0. N[O.sub.2] concentrations ranged from 9.2 ppb in Saint John to 25.6 ppb in Calgary, with a pooled average of 21.8. S[O.sub.2] concentrations ranged from 1.2 ppb in Winnipeg to 10.1 in Halifax, with a pooled average of 4.3 ppb, and CO concentrations ranged from 0.4 in London and to 1.2 ppm in Toronto, with a pooled average of 1.0 ppm. Pairwise Pearson correlations between pollutants were quite variable between cities. Correlations between N[O.sub.2], S[O.sub.2], and CO were all positive although they varied from 0.13 to 0.76 (Table 3). Correlations between P[M.sub.10] and [O.sub.3] and other pollutants varied from negative to positive, -0.55 to 0.71. We tested the association between air pollutants and hospitalization using lags of 0-5 days. Averaged over cities, the mean lags providing the greatest association were 2 days for [O.sub.3], 2 days for S[O.sub.2], 1 day for N[O.sub.2], and 1.8 days for CO. Based on minimization of the AIC, temperature was included in the models for Edmonton and Halifax. Relative humidity on the same day was included in all models except the two aforementioned cities. In addition, relative humidity lagged 1 day was included for Calgary, Vancouver, Windsor, and Winnipeg. Change in barometric pressure over the day did not enter the models. All individual pollutants were associated with increased respiratory hospitalizations, with N[O.sub.2] having the strongest effect whether or not adjusted for the other gases (Table 4). The independent effects of each gas remained stable whether or not adjusted for the effects of the other gases. The percent increases in hospitalization associated with an increase in air pollution equivalent to its interquartile range were 3.35 [95% confidence interval (CI), 1.73-4.77] for [O.sub.3], 2.85 (95% CI, 1.68-4.02) for N[O.sub.2], 1.66 (95% CI, 0.63-2.69) for S[O.sub.2], and 1.75 (95% CI, 0.48-3.02) for CO. The total effect of all gaseous pollutants was a 9.61% (4.52-14.7%) increase in respiratory admissions, with an increase in pollutants equivalent to their interquartile range. To determine the degree to which P[M.sub.10] may have confounded the findings, we restriced the analyses to every sixth day, when these pollutants were measured during the years 1986-2000. The gases remained statistically significant, with the largest difference in effect-size estimate found for the association between hospitalizations and S[O.sub.2]: 2.06% (95% CI, 1.04-3.08%) for the daily model versus 1.41% (95% CI, 0.35-2.47%) for the model restricted to every sixth day. Discussion Although admissions for respiratory disease are uncommon in neonates compared with adults, we were able to detect a significant association with gaseous air pollutants. If the association was causal, air pollution at ambient levels seen in Canada may account for 16% of admissions. Our results are consistent with previously observed associations in older children and adults between air pollution and respiratory symptoms, lung function, hospitalization, and mortality. The two strongest effects observed were with N[O.sub.2] and [O.sub.3]. A large meta-analysis of studies from around the world found consistent associations between mortality and N[O.sub.2] even when adjusted for other pollutants (Stieb et al. 2002). Associations have also been found linking all air pollutant gases with lung function impairment in both children and adults (Gauderman et al. 2000; Peters et al. 1999a, 1999b). In other observational studies observational studies, n.pl an investigational method involving description of the associations be-tween interventions and outcomes. Outcomes research and practice audits are examples of this investigational method. , acute changes in N[O.sub.2] have been associated with sudden infant death syndrome in Canada, infant mortality (hardware) infant mortality - It is common lore among hackers (and in the electronics industry at large) that the chances of sudden hardware failure drop off exponentially with a machine's time since first use (that is, until the relatively distant time at which enough mechanical in Mexico City Mexico City Spanish Ciudad de México City (pop., 2000: city, 8,605,239; 2003 metro. area est., 18,660,000), capital of Mexico. Located at an elevation of 7,350 ft (2,240 m), it is officially coterminous with the Federal District, which occupies 571 sq mi , and asthma symptoms in children (Dales et al. 2004; Delfino et al. 2002; Loomis et al. 1999). Exposures during pregnancy have been associated with low birth weight in Seoul, Korea, and IUGR in Vancouver, Canada (Ha et al. 2001; Liu et al. 2003). Controlled human exposures to N[O.sub.2] have demonstrated small increases in bronchial bronchial /bron·chi·al/ (brong´ke-al) pertaining to or affecting one or more bronchi. bron·chi·al adj. Relating to the bronchi, the bronchial tubes, or the bronchioles. reactivity (Folinsbee 1992) and an enhanced effect of allergen-induced bronchoconstriction (Strand et al. 1998). In mice, N[O.sub.2] exposure increases morbidity from Mycoplasma mycoplasma Any of the bacteria that make up the genus Mycoplasma. They are among the smallest of bacterial organisms. The cell varies from a spherical or pear shape to that of a slender branched filament. pulmonis (Parker et al. 1989) and mortality from Klebsiella Pneumoniae Klebsiella pneu·mo·ni·ae n. Friedlander's bacillus. (Ehrlich 1966; Gauderman et al. 2000; Peters et al. 1999a, 1999b; Stieb et al. 2002). The effects of N[O.sub.2] in large observational studies have been found at lower concentrations than those investigated in laboratory studies. Several possible reasons exist. The much larger sample size in population studies allows the ability to detect smaller effects. The laboratory studies control for other confounding variables better than can be done in an observational study In statistics, the goal of an observational study is to draw inferences about the possible effect of a treatment on subjects, where the assignment of subjects into a treated group versus a control group is outside the control of the investigator. . Perhaps N[O.sub.2] is simply a marker of other toxicants in a complex mixture of pollutants that share a common source. Nevertheless, our findings of increased neonatal morbidity from air pollution gases are consistent with other studies of early life. Particulates such as N[O.sub.2] are also markers of exposure to vehicular traffic. Although our study focused on air pollution gases, we had an opportunity to assess the effects of P[M.sub.10] measured every sixth day. A 10-[micro]g/[m.sup.3] increase in P[M.sub.10] has been associated with a 0.51-1% increase in all-cause mortality (Burnett et al. 1995) and a 1-4% increase in hospital visits (Pope et al. 1995). Our results were of similar magnitude, although in a different age group. We found a 1.5-2.1% increase in hospitalization among neonates associated with a 15-[micro]g/[m.sup.3] increase in P[M.sub.10], of similar magnitude to studies of other age groups. A more recent cohort study A cohort study is a form of longitudinal study used in medicine and social science. It is one type of study design. In medicine, it is usually undertaken to obtain evidence to try to refute the existence of a suspected association between cause and disease; failure to refute of cystic fibrosis cystic fibrosis (sĭs`tĭk fībrō`sĭs), inherited disorder of the exocrine glands (see gland), affecting children and young people; median survival is 25 years in females and 30 years in males. patients found that living in an area with a 10-[micro]g/[m.sup.3] higher concentration of P[M.sub.10] was associated with an 8% (95% CI, 2-15%) increase in the odds of at least two disease exacerbations requiring hospitalization or home intravenous antibiotics (Goss n. 1. Gorse. et al. 2004). For a 100-ppb increase in the daily one-hour maximum of [O.sub.3], Thurston and Ito (1999) reported that the relative risk of respiratory hospitalization for all ages was 1.18 (95% CI, 1.1-1.3), and the 1-sec forced expiratory volume forced expiratory volume n. Abbr. FEV The maximum volume of air that can be expired from the lungs in a specific time interval when starting from maximum inspiration. in children attending summer camps decreased by 50.0 (SE = 7.0) mL. Most of the literature on air pollution and health includes both adults and children together. The many reports of air pollution and children's health Children's Health Definition Children's health encompasses the physical, mental, emotional, and social well-being of children from infancy through adolescence. either excluded neonates (Farrow farrow see farrowing. et al. 1997; Gouveia and Fletcher 2000; Ha et al. 2003; Woodruff et al. 1997) or did not study them separately from all children (Burnett et al. 2001, 1994; Loomis et al. 1999). Yet neonates have a unique set of respiratory diagnoses such as acute life-threatening events and respiratory distress syndrome, whereas older children commonly suffer from asthma, croup croup (kr  p), acute obstructive laryngitis in young children, usually between the ages of three and six. , and
bronchiolitis Bronchiolitis DefinitionBronchiolitis is an acute viral infection of the small air passages of the lungs called the bronchioles. Description Bronchiolitis is extremely common. , and adults are admitted with asthma, pneumonia and chronic obstructive pulmonary disease chronic obstructive pulmonary disease n. Abbr. COPD A chronic lung disease, such as asthma or emphysema, in which breathing becomes slowed or forced. . We could not find previous studies of air pollution and hospitalization for neonatal respiratory disease, but the findings are consistent with the few published studies focusing on neonatal mortality Noun 1. neonatal mortality - the death rate during the first 28 days of life neonatal mortality rate death rate, deathrate, fatality rate, mortality rate, mortality - the ratio of deaths in an area to the population of that area; expressed per 1000 per year . Lin et al. (2004) reported that a 23.3-[micro]g/[m.sup.3] increase in P[M.sub.10] was associated with a 4% (95% CI, 2-6%) increase in total daily mortality in neonates in Sao Paulo, Brazil, whereas a 9.2-[micro]g/[m.sup.3] increase in S[O.sub.2] was associated with a 6% (95% CI, 4-8%) increase in mortality. The combined effects of the two pollutants was 6.3% (95% CI, 6.1-6.5%), indicating that the S[O.sub.2] alone could explain most of the effect. No significant effect of N[O.sub.2], CO, or [O.sub.3] could be detected, although an average of 6.1 deaths occurred daily over the 1,096 days of study. Bobak and Leon (1999) performed a case-control study case-control study, n an investigation employing an epidemiologic approach in which previously existing incidents of a medical condition are used in lieu of gathering new information from a randomized population. of live births in the Czech Republic Czech Republic, Czech Česká Republika (2005 est. pop. 10,241,000), republic, 29,677 sq mi (78,864 sq km), central Europe. It is bordered by Slovakia on the east, Austria on the south, Germany on the west, and Poland on the north. between 1989 and 1991. Each infant death was matched with 20 living infants who were of the same sex and born on the same day. No significant effect of total suspended particulates (TSP), S[O.sub.2], or N[O.sub.2] was found in the 1,684 cases of death in the neonatal period, adjusted for unspecified socioeconomic factors, gestational age ges·ta·tion·al age n. See estimated gestational age. Gestational age The estimated age of a fetus expressed in weeks, calculated from the first day of the last normal menstrual period. , and birth weight. Exposure to environmental tobacco smoke environmental tobacco smoke (ETS/passive smoke), n the gaseous by-product of burning tobacco products, including but not limited to commercially manufactured cigarettes and cigars; contains toxic elements harmful to the health of adults and children was not known. TSP and S[O.sub.2] were significantly associated with respiratory (n = 111 cases) but not all-cause deaths (n = 810) in the postneonatal period, with rate ratios of 1.95 (95% CI, 1.1-3.5) and 1.74 (95% CI, 1.0-3.0) respectively for an increase of 50 [micro]g/[m.sup.3]. Lipfert et al. (2000) matched the U.S. Environmental Protective Agency's air pollution database with the National Linked Birth/Infant Death Data Set of the National Center for Health Statistics National Center for Health Statistics (NCHS) is part of the Centers for Disease Control and Prevention (CDC), which is part of the United States Department of Health and Human Services. NCHS is the United States' principal health statistics agency. for 1990. Annual averages of air pollution were estimated for each infant based on the county of birth. S[O.sub.4] and P[M.sub.10] were positively associated with total neonatal deaths, and P[M.sub.10] was associated with neonatal respiratory deaths, adjusted for mother's smoking, marital status marital status, n the legal standing of a person in regard to his or her marriage state. , race, infant's month of birth, and average heating degree days. There were no associations with CO, and associations with S[O.sub.2] and N[O.sub.2] were not reported. Dales et al. (2004) reported that between 1984 and 1999, daily increases in S[O.sub.2] and N[O.sub.2] equivalent to their interquartile ranges were associated with an 18% increase in daily SIDS. The study was based on infant deaths occurring in the same Canadian cities on which the present study is based. Even earlier in life, there is emerging evidence suggesting adverse effects of air pollution. In British Columbia, lower birth weight has been found in areas of higher air pollution adjusting for maternal age maternal age, n the age of the mother at the period of conception. , parity, infant sex, gestational age or birth weight, and month of birth (Liu et al. 2003). However, socioeconomic status socioeconomic status, n the position of an individual on a socio-economic scale that measures such factors as education, income, type of occupation, place of residence, and in some populations, ethnicity and religion. , a potential confounder, was not accounted for in the study. 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Peters JM, Avol E, Gauderman WJ, Linn linn n. Scots 1. A waterfall. 2. A steep ravine. [Scottish Gaelic linne, pool, waterfall.] WS, Navidi W, London SJ, et al. 1999a. A study of twelve southern California communities with differing levels and types of air pollution. II. Effects on pulmonary function. Am J Respir Crit Care Med 159:768-775. Peters J, Avol E, Navidi W, London SJ, Gauderman WJ, Lurmann F, et al. 1999b. A study of twelve southern California communities with differing levels and types of air pollution. I. Prevalence of respiratory morbidity. Am J Resp Crit Care Med 159:760-767. Pope CA III, Bates Bates , Katherine Lee 1859-1929. American educator and writer best known for her poem "America the Beautiful," written in 1893 and revised in 1904 and 1911. DV, Raizenne ME. 1995. Health effects of particulate air pollution: time for reassessment? Environ Health Perspect 103:472-480. Ritz B, Yu F, Fruin S, Chapa G, Shaw GM, Harris JA. 2002. Ambient air pollution and risk of birth defects birth defects, abnormalities in physical or mental structure or function that are present at birth. They range from minor to seriously deforming or life-threatening. A major defect of some type occurs in approximately 3% of all births. in southern California. Am J Epidemiol 155:17-25. Statistics Canada. 1996. Census of Population. Available: http://www12.statcan.ca/english/census01/info/census96.cfm [accessed 22 September 2006]. Stieb DM, Judek S, Burnett RT. 2002. Meta-analysis of time-series studies of air pollution and morality: effects of gases and particles and the influence of cause of death, age, and season. J Air Waste Manag Assoc 52:470-484 Strand V, Svartengren M, Rak S, Barck C, Bylin G. 1998. Repeated exposure to an ambient level of N[O.sub.2] enhances asthmatic response to a nonsymptomatic allergen allergen /al·ler·gen/ (al´er-jen) an antigenic substance capable of producing immediate hypersensitivity (allergy).allergen´ic pollen allergen dose. Eur Respir J 12:6-12. Thurston GD, Ito K. 1999. Epidemiological studies of ozone exposure effects. In: Air Pollution and Health Toronto:Academic Press, 485-510. Wang X, Ding H, Ryan L, Xu X. 1997. Associations between air pollution and low birth weight: a community based study. Environ Health Perspect 105:514-520. Woodruff TJ, Grillo J, Schoendorf KC. 1997. The relationship between selected causes of postneonatal infant mortality and particulate air pollution in the United States. Environ Health Perspect 105:608-612. World Health Organization. 1975. International Classification of Disease, 9th Revision. Geneva Geneva, canton and city, Switzerland Geneva (jənē`və), Fr. Genève, canton (1990 pop. 373,019), 109 sq mi (282 sq km), SW Switzerland, surrounding the southwest tip of the Lake of Geneva. :World Health Organization. Robert E. Dales, (1,2,3) Sabit Cakmak, (3) and Marc Smith Doiron (3) (1) University of Ottawa Address correspondence to R. Dales, The Ottawa Hospital (General Campus), 501 Smyth Rd., Box 211, Ottawa, Ontario K1H 8L6 Canada. Telephone: (613) 737-8198. Fax: (613) 739-6266. E-mail: rdales@ohri.ca The authors declare they have no competing financial interests. Received 26 January 2006; accepted 3 August 2006.
Table 1. Frequency of occurrence of respiratory diagnoses in 11 Canadian
cities, 1 January 1986 to 31 December 2000.
1996 Census Dyspnea and
population Respiratory respiratory
City (x [10.sup.5]) Asphyxia failure abnormalities
Calgary 7.68 2 13 209
Edmonton 6.16 0 9 215
Halifax 1.80 0 1 46
Hamilton 2.45 1 6 181
London 1.25 1 11 82
Ottawa 9.39 1 14 173
Saint John 1.02 0 1 57
Toronto 23.85 9 22 821
Vancouver 18.32 4 30 555
Windsor 1.98 2 4 105
Winnipeg 6.88 0 15 97
Total 20 126 2,541
Respiratory Unspecified Other respiratory
distress birth asphyxia problems
City syndrome in live born after birth
Calgary 272 19 270
Edmonton 143 53 268
Halifax 1 0 14
Hamilton 107 4 76
London 21 4 110
Ottawa 99 26 104
Saint John 1 0 12
Toronto 789 189 543
Vancouver 1,510 82 367
Windsor 22 3 34
Winnipeg 21 11 110
Total 2,986 391 1,908
City Pneumonia All respiratory diagnoses
Calgary 26 811
Edmonton 54 742
Halifax 8 70
Hamilton 27 402
London 24 253
Ottawa 32 449
Saint John 3 74
Toronto 212 2,585
Vancouver 111 2,659
Windsor 21 191
Winnipeg 96 350
Total 614 8,586
Census data from Statistics Canada 1996.
Table 2. Population size, 24-hr mean air pollution levels (5th, 95th
percentiles), and weather variables for 11 Canadian cities, 1 January
1986 to 31 December 2000.
City [O.sub.3] (ppb) N[O.sub.2] (ppb) S[O.sub.2] (ppb)
Calgary 17.8 (4.7, 32.3) 25.6 (13.3, 41.0) 3.6 (1.0, 8.0)
Edmonton 17.0 (4.0, 33.1) 24.6 (11.5, 43) 2.7 (0, 6.0)
Halifax 20.8 (9, 35) 15.1 (3, 28) 10.1 (2, 23)
Hamilton 19.0 (3.3, 41.8) 20.8 (11, 34) 8.2 (1.7, 17.5)
London 22.3 (6, 46) 20.0 (8, 35) 3.7 (0, 11)
Ottawa 16.4 (4.5, 31.0) 21.2 (7, 38) 3.9 (0, 10)
Saint John 23.1 (10.7, 38.5) 9.2 (2, 21) 8.3 (0.5, 23.5)
Toronto 18.3 (5, 36.7) 25.1 (14, 39) 4.5 (0.2, 11.3)
Vancouver 13.3 (3.2, 24.9) 19.0 (11.4, 30.2) 4.6 (1.2, 9.8)
Windsor 18.7 (3, 42) 24.9 (11, 41) 7.6 (1.7, 15.7)
Winnipeg 18.5 (6, 34) 15.2 (6, 28) 1.2 (0, 3.5)
Population 17.0 21.8 4.3
weighted
average
City CO (ppb) Mean temperature ([degrees]C)
Calgary 0.9 (0.4, 2.0) 4.5 (-15.5, 18.4)
Edmonton 1.1 (0.4, 2.4) 3.0 (-19.5, 18.1)
Halifax 0.8 (0.3, 1.7) 6.4 (-10.4, 10.3)
Hamilton 0.9 (0.2, 1.6) 7.9 (-9.4, 22.8)
London 0.4 (0, 1.2) 7.9 (-9.7, 22.9)
Ottawa 0.9 (0.2, 1.9) 6.3 (-15, 23)
Saint John 0.7 (0.1, 1.7) 5.1 (-12.6, 18.6)
Toronto 1.2 (0.6, 1.9) 8.1 (-9.6, 23.4)
Vancouver 0.9 (6.4, 1.9) 10.5 (1.5, 19.1)
Windsor 0.8 (0, 1.5) 9.8 (-7.3, 25.1)
Winnipeg 0.6 (0.3, 1.0) 3.1 (-22.6, 22.1)
Population 1.0 7.2
weighted
average
24-hr change in
City barometric pressure % Relative humidity
Calgary 0.0 (-1.1, 1.13) 61.2 (37, 86)
Edmonton 0.0 (-1.2, 1.2) 68.6 (47, 88)
Halifax 0.0 (-1.7, 1.6) 77.5 (54, 96)
Hamilton 0.0 (-1.3, 1.3) 73.5 (50, 95)
London 0.0 (-1.25, 1.27) 75.7 (55, 93)
Ottawa 0.0 (-1.5, 1.5) 69.4 (46, 91)
Saint John 0.0 (-1.6, 1.5) 75.4 (52, 95)
Toronto 0.0 (-1.4, 1.3) 71.9 (52, 90)
Vancouver 0.0 (-1.1, 1.2) 79.3 (64, 94)
Windsor 0.0 (-1.2, 1.3) 70.8 (51, 91)
Winnipeg 0.0 (-1.4, 1.4) 71.9 (49, 91)
Population 48.1 72.3
weighted
average
Table 3. Range of Pearson pairwise correlations between pollutants by
city for 11 Canadian cities, 1 January 1986 to 31 December 2000.
P[M.sub.10] [O.sub.3] N[O.sub.2] S[O.sub.2]
P[M.sub.10]
[O.sub.3] -0.29 to 0.41
N[O.sub.2] -0.26 to 0.69 -0.55 to 0.05
S[O.sub.2] -0.09 to 0.61 -0.41 to 0.13 0.20 to 0.67
CO -0.13 to 0.71 -0.54 to -0.01 0.13 to 0.76 0.19 to 0.66
Table 4. The pooled estimate of percent increase (95% CI) in neonatal
respiratory hospital admissions associated with an increase in air
pollution concentration increase equal in magnitude to its interquartile
range. Data from 11 Canadian cities, 1 January 1986 to 31 December 2000.
Air pollutants Interquartile range Single-pollutant model (a)
[O.sub.3] (ppb) 12.0 3.21 (1.72 to 4.70)
N[O.sub.2] (ppb) 10.0 2.94 (1.93 to 3.95)
S[O.sub.2] (ppb) 3.8 2.06 (1.04 to 3.08)
CO (ppm) 0.5 1.75 (0.63 to 2.87)
P[M.sub.10] 15.2 2.13 (-0.5 to 4.76)
([micro]g/
[m.sup.3])
Multipollutant model (b)
Multi-pollutant restricted to days with
Air pollutants model (b) P[M.sub.10] measures
[O.sub.3] (ppb) 3.35 (1.73 to 4.77) 2.67 (0.98 to 4.39)
N[O.sub.2] (ppb) 2.85 (1.68 to 4.02) 2.48 (1.18 to 3.80)
S[O.sub.2] (ppb) 1.66 (0.63 to 2.69) 1.41 (0.35 to 2.47)
CO (ppm) 1.75 (0.48 to 3.02) 1.30 (0.13 to 2.49)
P[M.sub.10] 1.45 (-1.90 to 4.80)
([micro]g/
[m.sup.3])
(a) Effect size is adjusted for long-term temporal trends, day of week
effects, and weather variables. (b) Effect size is adjusted for other
gases and size is adjusted for long-term temporal trends, day of week
effects, and weather variables.
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