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Outdoor particulate air pollution and indoor renovation associated with childhood pneumonia in China
Atmospheric Environment 174 (2018) 76–81
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Outdoor particulate air pollution and indoor renovation associated with childhood pneumonia in China
T
Wei Jianga,1, Chan Lua,1, Yufeng Miaoa, Yuguang Xianga, Lv Chenb, Qihong Denga,b,c,d,∗ a
School of Energy Science and Engineering, Central South University, Changsha, Hunan, China XiangYa School of Public Health, Central South University, Changsha, Hunan, China c Institute of Environmental Health, Central South University, Changsha, Hunan, China d Collaborative Innovation Center of Building Energy Conservation & Environmental Control, Hunan, China b
G RA P H I C A L AB S T R A C T
A R T I C L E I N F O
A B S T R A C T
Keywords: Pneumonia Ambient air pollution Indoor air pollution New furniture Redecoration Urbanization
Background: Pneumonia is a common early-childhood respiratory infection that leads to long-term health impacts, but its risk factors remain unclear. Objective: To examine the association between early life exposure to both outdoor and indoor air pollution and childhood pneumonia. Methods: We conducted a retrospective cohort study of 2598 children aged 3–6 years in Changsha, China (20112012). Children's life-time prevalence of pneumonia and exposure to indoor air pollution related to home renovation were surveyed by a questionnaire answered by the parents. Children's exposure to outdoor air pollution, including nitrogen dioxide (NO2), sulfur dioxide (SO2), and particulate matter with an aerodynamic diameter ≤ 10 μm (PM10), was estimated using the measured concentrations at monitoring stations. Association between childhood pneumonia and exposure to indoor and outdoor air pollution during both prenatal and postnatal periods were examined by using logistic regression model in terms of odds ratio (OR) and 95% confidence interval (CI). Results: Life-time prevalence of pneumonia in preschool children in Changsha is high, up to 38.6%.We found that childhood pneumonia was associated with postnatal exposure to outdoor particulate air pollutant PM10, adjusted OR (95% CI) = 1.26 (1.00–1.57) for per 6 μg/m3 increase in the concentration. Pneumonia was also associated with postnatal exposure to indoor renovation, adjusted OR (95% CI) = 1.30 (1.02–1.64) for new furniture and 1.30 (1.00–1.69) for redecoration. Combined exposure to outdoor high PM10 and indoor renovation significantly increased the pneumonia risk. Sensitivity analysis indicated that the association was heterogeneous in different subgroups, but stronger in male and younger children.
∗
1
Corresponding author. XiangYa School of Public Health, Central South University, Changsha 410083, Hunan, China. E-mail address: [email protected] (Q. Deng). These authors contributed equally to this work.
https://doi.org/10.1016/j.atmosenv.2017.11.043 Received 12 April 2017; Received in revised form 20 November 2017; Accepted 26 November 2017 Available online 27 November 2017 1352-2310/ © 2017 Elsevier Ltd. All rights reserved.
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Conclusion: High prevalence of childhood pneumonia in China may be associated with postnatal exposure to ambient particulate air pollution and house renovation.
1. Introduction
response rate) but excluded: (1) 745 children in kindergartens with response rate < 50%, as the children are mainly from the rural areas and thus their exposure during pregnancy cannot be estimated; (2) 162 children with low birth weight (< 2.5 kg) or preterm birth (< 37 weeks of gestation) and 10 children with multiple births, as these conditions may confound the effect of air pollution; (3) 80 children younger than 3 and older than 6, because they are too few; (4) 302 children without information about pneumonia. Totally, the 2598 complete data sets were entered into a database.
Pneumonia is one of the most common reasons for hospital admission and the first leading cause of death in children (Liu et al., 2012; Walker et al., 2013). Pneumonia accounted for 15 percent of all underfive deaths and killed 920,000 children in 2015; 99% of deaths occurred in low and middle income countries (Zar et al., 2013). In addition, childhood pneumonia has wide-ranging complications and sequelae in later life, which not only has a crippling effect on child's development and quality of life but also results in heavy economic burden for both family and society (Le et al., 2014; Walker et al., 2013). Most pneumonia are preventable (Bhutta et al., 2013), and therefore there is a critical need to investigate the main risk factors of pneumonia so as to provide more effective preventative strategies. Childhood clinical pneumonia is a complex disease caused by a combination of host, infection and the environment factors (Rudan et al., 2008). Although host and infection factors strongly influence the risk of pneumonia, environmental factors have been shown to be a significant risk factor for the development of pneumonia (Miao et al., 2017; Zeng et al., 2017). Recent studies have suggested that outdoor air pollution was associated with childhood pneumonia, but mainly focused on the association between short-term exposure and emergency department visits for pneumonia (Fusco et al., 2001; Neupane et al., 2010). The effect of long-term exposure to air pollution on childhood pneumonia is unclear and has never been investigated. On the other hand, indoor air pollution may have a greater impact than outdoor air pollution because children spend 90% of their time indoors (Nazaroff and Goldstein, 2015; Zhang and Smith, 2003). With the rapid economic growth and urbanization process in China during the past decade, a huge amount of people, particularly the new couples and expectant parents, have moved into new buildings with redecoration and new furniture (Deng et al., 2015b). The new house and house renovation have become a major source of indoor air pollution and their impact on the health of children who was born or will be born is an increasing concern in China (Gao et al., 2014). However, there is a lack of examination for the risk of childhood pneumonia due to indoor air pollution generated by renovation. Recently, early-life exposure to air pollution has attracted considerable attention, as it influences developmental plasticity and hence leads to later development of a variety of complex diseases (Deng et al. 2016a,b, 2017; Gluckman et al., 2008; Suk et al., 2016). Therefore, our study aims to examine childhood pneumonia risk due to early life exposure to outdoor air pollution and indoor renovation in China during both prenatal and postnatal periods, so as to identify the susceptible windows of exposure and key components of air pollution in the development of pneumonia. Accordingly, we carried out a cohort study in Changsha, a part of nationwide multi-center “China-Children-HomesHealth (CCHH)” study (Zhang et al., 2013).
2.2. Exposure timing windows Children's exposure was divided into prenatal and postnatal periods. The prenatal exposure referred to the exposure during the entire pregnancy that was defined as from the first month to the last month of pregnancy, and the postnatal exposure was defined as the exposure during the period from the first year to the past year. 2.3. Exposure to ambient air pollution Ambient air pollution was characterized by three criteria pollutants: sulfur dioxide (SO2), nitrogen dioxide (NO2), and particulate matter ≤ 10 μm in diameter (PM10). We obtained daily average concentrations of the air pollutants from 7 municipal air quality monitoring stations. Children's daily exposure were estimated by air pollutant concentrations at the kindergartens that were projected from those at the stations by using an inverse distance weight (IDW) method (Deng et al., 2015a). Prenatal exposure was calculated as average of the monthly mean concentrations of PM10, SO2 and NO2 during the full gestational months. Postnatal exposure was calculated as the average of the monthly mean concentrations of air pollutants during all months from the first year to the past year. 2.4. Exposure to indoor renovation Children's exposure to indoor renovation in terms of new furniture and redecoration was assessed by the questionnaire survey. Exposure to new furniture was assessed by the question: “Did you install new furniture in your house (Yes/No/Don't know)?” and if yes, “When did you install the new furniture (During pregnancy/First year of life/After first year of life)?” Exposure to redecoration was assessed by another question:“Did you redecorate your house (Yes/No/Don't know)?” and if yes, “When did you redecorate your house (During pregnancy/First year of life/After first year of life)?” 2.5. Health outcome
2. Method
The health outcome of the questionnaire, lifetime prevalence of pneumonia, was based on the answer to the question: “Has your child ever been diagnosed with pneumonia?”
2.1. Study population
2.6. Confounding covariates
We conducted a survey for respiratory disease in children in Changsha during the period from September 2011 to January 2012. The study protocol and questionnaire were described elsewhere (Deng et al., 2015a). We distributed 4988 questionnaires to the children at 36 randomly selected kindergartens. Children were instructed to have the questionnaire completed by parents and to return it to kindergartens within one week. We received 3897 completed questionnaires (78%
Potential confounding variables are also obtained from the questionnaires that include: (1) child-related covariates included sex, age, birth season, breast-feeding, day-care attendance; (2) parent-related covariates included parental atopy and socioeconomic status (SES) indicating by housing size; (3) residential-related covariates included environmental tobacco smoke (ETS), visible mold/damp stains at home, and window condensation in winter. It was identified that these 77
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41.9%) than that during prenatal period (38.2% and 35.0%). The association between exposure to outdoor air pollutants and childhood pneumonia was shown in Table 4. We found that the pneumonia was not associated with SO2 and NO2, but only significantly associated with postnatal exposure to PM10 with adjusted OR (95% CI) = 1.26 (1.00–1.57) for per IQR increase (6 μg/m3). The association was robust and consistent after adjustment for multi-windows, and further adjustment for multi-pollutants (Table S1, as shown in supplemental materials). The association between exposure to indoor renovation and childhood pneumonia was shown in Table 5. Childhood pneumonia was also only significantly associated with postnatal exposure to new furniture and redecoration with adjusted OR (95% CI) = 1.30 (1.02–1.64) and 1.30 (1.00–1.69) respectively. The association between postnatal exposure to combined outdoor PM10 and indoor renovation and childhood pneumonia was presented in Table 6. We found that exposure to both outdoor high PM10 and indoor renovation posed the highest and significant risk, as compared to the risk of exposure to low PM10 in outdoors and no renovation in indoors. Fig. 1 shows the sensitivity analysis of the association between childhood pneumonia and postnatal exposure to outdoor PM10 and indoor renovation in different subgroups stratified by the significant covariates shown in Table 1. We found that the association was heterogeneous, but stronger in male and younger children and also in children without parental atopy and living in houses without mold/ dampness.
confounders were related to childhood pneumonia and may influence the affect estimates. Children's birth season was divided into Spring (March to May), Summer (June to August), Autumn (September to November) and winter (December to February). Parental atopy was defined as a history of maternal or paternal asthma, allergic rhinitis and eczema. 2.7. Statistical analysis Multiple logistic regression analysis was implemented to evaluate the association between pneumonia in children and their exposure to outdoor air pollution or indoor renovation during prenatal and postnatal periods adjusting for covariates. Association was calculated as odds ratio (OR) with 95% confidence interval (95% CI) and the value p < 0.05 was considered to be statistically significant. Outdoor air pollutants were entered into the regression model as continuous variables, and their risks of pneumonia were estimated by an interquartile range (IQR) increase in exposure levels. A single-pollutant model was firstly examined, and then a multi-pollutant model was carried out to mutually adjust the effects of other air pollutants so as to obtain the independent association of each air pollutant with childhood pneumonia, and finally a multi-window model was investigated to further obtain the independent risk of exposure in prenatal or postnatal period (Deng et al., 2016a). Indoor new furniture and redecoration were entered into the model as categorical variables. In order to obtain the independent risk of exposure to indoor renovation during different periods, we divided the exposure into four mutually exclusive categories: not exposed in either prenatal or postnatal period (the reference category with OR = 1), exposed in prenatal but not postnatal period, exposed postnatal but not prenatal period, and exposed in both prenatal and postnatal periods. Furthermore, sensitivity analyses were conducted to examine the heterogeneity in different subgroups. All statistical analyses were performed by SPSS software (version 16.0, SPSS Inc, Chicago, USA).
Table 1 Covariates, demographic information and prevalence of pneumonia among children aged 3–6 years old (n = 2598). Number
(%)
Case
(%)
Total 2598 (100) 1004 (38.6) Child's Sex Boys 1399 (54) 571 (40.8) Girls 1199 (46) 433 (36.1) Birth season Spring 598 (23) 228 (38.1) Summer 744 (29) 278 (37.4) Autumn 666 (26) 258 (38.7) Winter 590 (23) 240 (40.7) Age 3 665 (26) 233 (35) 4 952 (37) 395 (41.5) 5 815 (31) 301 (36.9) 6 166 (6) 75 (45.2) Breast-feeding No 222 (9) 99 (44.6) Yes 2376 (91) 905 (38.1) Day-care attendance (years old) <3 615 (24) 250 (40.7) ≥3 1971 (76) 749 (38) Parental Parental atopy No 2214 (85) 826 37.3 Yes 340 (13) 167 49.1 Parental socioeconomic status (SES) by house size (m2) ≤75 836 (32) 306 (36.6) > 75 1732 (67) 690 (39.8) Residential Environmental tobacco smoke (ETS) at home No 864 (33) 329 (38.1) Yes 1734 (67) 675 (38.9) Visible mold/damp stains at home No 1985 (76) 742 (37.4) Yes 606 (23) 258 (42.6) Window condensation in winter No 1175 (45) 431 (36.7) Yes 1369 (53) 553 (40.4)
3. Results Of 2598 children, 1004 (38.6%) had a history of doctor-diagnosed pneumonia. Table 1 shows the demographics and lifetime prevalence of pneumonia stratified by covariates. In this study, 54% of the children were male and 46% were female. The children were born uniformly across the seasons and 91% were breast-fed. About 13% of the children's parents have atopic diseases. Two-third of the children lived in houses with ETS, 23% of the children in houses with visible mold and dampness, and half of the children in houses with window condensation during winter. We found that the prevalence was significantly associated with some child's, parental and residential factors: the prevalence is significantly higher in children who are male (p = 0.012), older (p = 0.010), without breast-feeding (p = 0.049) and with parental atopy (p = 0.0) and also higher for those living houses with visible mold/dampness (p = 0.020) and window condensation (p = 0.048). Children's exposure to outdoor air pollutants was summarized in Table 2. The average individual exposure to the classic air pollutants (PM10 and SO2) were substantially decreased from prenatal levels of 110 μg/m3 and 82 μg/m3 to postnatal 93 μg/m3 and 51 μg/m3, but exposure to the traffic-related air pollutant (NO2) was slightly increased from prenatal 46 μg/m3 to postnatal 49 μg/m3. Children's exposure to indoor renovation was shown in Table 3. Very few families installed new furniture (7.4%) and redecorated their houses (3.1%) during pregnancy (prenatal), but 37.7% and 19.2% families respectively installed new furniture and redecorated their houses after the children were born (postnatal). Table 3 also showed the prevalence of pneumonia in the children living in these families. We found that the prevalence of childhood pneumonia for exposure to new furniture and redecoration was higher during postnatal period (40.8% and
p-value –
0.012
0.648
0.010
0.049
0.215
0.000
0.115
0.675
0.020
0.048
Sum of the number is not 2598 due to missing data. The values p < 0.05 were in bold.
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indoor new furniture/redecoration. We further observed that combined exposure to outdoor PM10 and indoor renovation significantly increased the risk of pneumonia in children. Our study protocol has several strengths. Firstly, we conducted a large cohort study in one city assessed by individual exposure using an inverse distance weighted (IDW) method, in contrast to limited previous analyses that have been conducted with small study populations and have focused largely on cross-sectional comparisons between different geographic regions. Secondly, we identified susceptible window of exposure and key component of air pollution in the development of childhood pneumonia by analysing its association with different air pollutants during different exposure periods. Thirdly, we investigated the association between the combined outdoor and indoor air pollution with childhood pneumonia. We found long-term postnatal exposure to particulate air pollutant (PM10) significantly increased the risk of pneumonia in children. Although no studies examined the risk of long-term exposure to ambient air pollution for childhood pneumonia, our finding is consistent with some short-term studies. Exposure to PM10 were found to be associated with increased risk of daily hospital admissions of pneumonia in children in Brazil (Braga et al., 2001) and Vietnam (Mehta et al., 2013). In addition, childhood pneumonia hospitalization was found to be significantly associated with exposure to coarse (PM10–2.5) and fine (PM2.5), and even ultrafine particles (Fusco et al., 2001; Yang et al., 2004; Zanobetti and Schwartz, 2006). Our findings were also supported by a recent case-crossover study in China (Duan et al., 2016), which found that high level PM2.5 increase the risk of hospitalization for pneumonia. We found an association between exposure to indoor new furniture/ redecoration and childhood pneumonia. Early childhood pneumonia has been found to be closely related to indoor environmental factors, but mainly for solid fuels (Accinelli et al., 2017; Dherani et al., 2008; Ram et al., 2014; Smith et al., 2011) and parental smoking or environmental tobacco smoke (ETS) (DiFranza et al., 2004; Suzuki et al., 2009). In China, due to the rapid economic growth during the past decades, children exposure to unprocessed solid fuels and ETS at home has been greatly reduced. However, due to the rapid urbanization progress, a huge number of people, especially the new couples and expectant parents, migrated into new buildings during the past decade (Du et al., 2014). The risk of renovation and new furniture to the children has rarely been investigated, but several studies found that indoor renovation or new furniture were associated with increased likelihood of respiratory symptoms, allergic rhinitis, asthma (Coombs et al., 2016; Dai et al., 2016; Deng et al., 2015b; Dong et al., 2014; Mendell, 2007). Our findings were supported by one recent populationbased cross-sectional study in Nanjing (Zheng et al., 2013), which found that new furniture and decorative materials were significantly associated with pneumonia among children. Our results indicated that childhood pneumonia is still serious in China. Our study observed that the lifetime prevalence incidence in Changsha is high up to 38.6% episodes, comparable the recent data in
Table 2 Statistics of exposure to outdoor air pollution among children aged 3–6years (n = 2598). Mean Prenatal PM10 110 SO2 82 NO2 46 Postnatal PM10 93 SO2 51 NO2 49
25th Percentile
50th Percentile
75th Percentile
IQR
103 62 40
108 75 45
115 98 52
12 36 12
90 42 43
93 49 49
96 57 55
6 15 12
PM10 (μg/m3) = particulate matter ≤ 10 μm in aerodynamic diameter; SO2 (μg/ m3) = sulfur dioxide; NO2 (μg/m3) = nitrogen dioxide; IQR = interquartile range. Table 3 Statistics of exposure to indoor renovation and pneumonia cases among children aged 3–6years (n = 2598).
Prenatal New furniture Redecoration Postnatal New furniture Redecoration
n (%)
Case (%)
191 (7) 80 (3)
73 (38.2) 28 (35.0)
980 (38) 499 (19)
400 (40.8) 209 (41.9)
Table 4 Odds ratio (95% CI) of childhood pneumonia for exposure to air pollution among children aged 3–6years (n = 2598). Multi-window modelb
Single-pollutant model
Prenatal PM10 SO2 NO2 Postnatal PM10 SO2 NO2
Crude
Adjusteda
1.04 (0.95, 1.14) 0.95 (0.85, 1.06) 0.87 (0.77, 0.98)*
0.93 (0.77, 1.12) 0.92 (0.76, 1.11) 0.86 (0.70, 1.04)
0.92 (0.76, 1.11) 0.77 (0.58, 1.02) 0.77 (0.50, 1.19)
1.13 (1.01, 1.26)* 1.04 (0.93, 1.16) 0.89 (0.76, 1.05)
1.26 (1.00, 1.57)* 1.05 (0.87, 1.26) 0.88 (0.70, 1.10)
1.26 (1.01, 1.59)* 1.28 (0.96, 1.70) 1.15 (0.69, 1.91)
OR (95%CI) was estimated for an IQR increase in PM10, SO2, and NO2. *p ≤ 0.05. a Single-pollutant model: adjustment for all the covariates in Table 1. b Multi-window model: further adjustment for the effects of the air pollutant in other window on the base of single-pollutant model.
4. Discussion In this population-based cohort study, we found that the lifetime prevalence of pneumonia in preschool children was significantly associated with postnatal exposure to particulate air pollutant PM10 and
Table 5 Odds ratio (95%CI) of childhood pneumonia for pre- and post-natal exposure to indoor renovation among children aged 3–6years (n = 2598).
New furniture
Redecoration
Prenatal
Postnatal
n (%)
Crude OR (95%CI)
Adjusted OR (95%CI)
No No Yes Yes No No Yes Yes
No Yes No Yes No Yes No Yes
1248 (48) 818 (31) 176 (7) 162 (6) 1689 (65) 481 (19) 121 (5) 18 (1)
1.00 1.26 1.30 1.03 1.00 1.20 1.05 1.66
1.00 1.30 1.24 0.92 1.00 1.30 1.14 0.64
*p ≤ 0.05. **p ≤ 0.01. a Adjustment for all the covariates in Table 1.
79
(1.05, 1.51)* (0.94, 1.79) (0.73, 1.45) (0.97, 1.47) (0.72, 1.54) (0.65, 4.19)
(1.02, 1.64)* (0.82, 1.88) (0.59, 1.45) (1.00, 1.69)* (0.71, 1.85) (0.16, 2.54)
a
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Table 6 Odds ratio (95% CI) of childhood pneumonia for combined postnatal exposure to outdoor PM10 and indoor new furniture/redecoration among children aged 3–6years (n = 2598).
Postnatal PM10 Low Low High High Postnatal PM10 Low Low High High
Postnatal New furniture No Yes No Yes Postnatal Redecoration No Yes No Yes
n (%)
Crude OR (95% CI)
Adjusted OR (95% CI)
782 475 836 505
1.00 1.14 (0.91, 1.45) 1.08 (0.88, 1.32) 1.27 (1.01, 1.60)*
1.00 1.13 (0.89, 1.44) 1.08 (0.88, 1.33) 1.27 (1.00, 1.60)*
1.00 0.89 (0.66, 1.20) 0.98 (0.83, 1.18) 1.47 (1.12, 1.92)**
1.00 0.86 (0.63, 1.16) 0.98 (0.82, 1.18) 1.46 (1.11, 1.93)**
(30) (18) (32) (19)
1027 (40) 230 (9) 1072 (41) 269 (10)
a
Low and high exposure of PM10 is indicated by the personal exposure ≤ and > median value. *p ≤ 0.05. **p ≤ 0.01. a Adjustment for all the covariates in Table 1.
Murta et al., 2016; Wang et al., 2014). A recent study further suggested that long-term VOCs inhalation even at low levels can caused oxidative stress and genotoxicity response in mice (Wang et al., 2013, 2014). There are some limitations of this study that should be acknowledged. The first limitation is the potential misclassification of exposure. We estimated children's daily exposure to ambient air pollution according to their exposure in kindergarten only. It will be much better if we could average the daily exposure according to the exposure in kindergarten during daytime and the exposure at home during nighttime. However, we didn't ask the children's home address in our questionnaire because it is a very sensitive and private question in China. However, the exposure assessment was reasonable by considering the situation in China that the parents usually enrolled their children in kindergarten nearest to their home and that mother usually worked near home or kindergartens. Secondly, we estimated children's prenatal exposure to ambient air pollution based on their mother's exposure, which is not the same to fetus's exposure or in-utero exposure. This exposure misclassification is an intrinsic limitation of our study, because the in-utero exposure has to be estimated by using the blood biomarkers (Madhloum et al., 2017). Thirdly, we didn't measure the indoor VOCs concentrations emitted from the new furniture and
other cities in China (Qu et al., 2017), that is much higher than 0.05 episodes in developed countries (Guan et al., 2010; Rudan et al., 2008; Walker et al., 2013). Our findings indicated that “double exposure” to the high level of ambient air pollution and high rate of house renovation in China may contribute to the high prevalence of childhood pneumonia. Although the exact mechanism is not well understood, the association between postnatal exposure to outdoor particulate air pollution and indoor renovation and lifetime prevalence of pneumonia in children is biologically plausible. On one hand, the infant and child's respiratory and immunological systems are developing and hence are easily affected by the detrimental health effect of air pollution. Especially, the infant and child's alveoli are developing fast after birth, and pneumonia is kind of infection in alveoli. On the other hand, it has been demonstrated that PM10 can produce a large quantity of reactive oxygen species which trigger the inflammatory processes in the respiratory tract (Li et al., 2003). Meanwhile, redecoration and new furniture in homes has led to elevated levels of indoor VOCs (Dai et al., 2016). Several recent in vitro studies also demonstrated that exposure to indoor relevant concentrations of VOCs increased the production of inflammatory cytokines in human lung epithelial cell lines by the induction of oxidative stress or inflammation (Mascelloni et al., 2015;
Fig. 1. Sensitivity analysis for the association between childhood pneumonia and postnatal exposure to outdoor PM10 and indoor new furniture/redecoration by the significant covariates (as shown in Table 1).
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redecoration. The association between childhood pneumonia and indoor VOCs concentrations will be much helpful and provide strong evidence to understand the health effect of new furniture and redecoration.
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Oxidative damage and genotoxic effect in mice caused by sub-chronic exposure to low-dose volatile organic compounds. Inhal. Toxicol. 25, 235–242. Wang, F., Li, C., Liu, W., Jin, Y., Guo, L., 2014. Effects of subchronic exposure to low-dose volatile organic compounds on lung inflammation in mice. Environ. Toxicol. 29, 1089–1097. Yang, Q., Chen, Y., Krewski, D., Shi, Y., Burnett, R.T., Mcgrail, K.M., 2004. Association between particulate air pollution and first hospital admission for childhood respiratory illness in vancouver, Canada. Arch. Environ. Health 59, 14–21. Zanobetti, A., Schwartz, J., 2006. Air pollution and emergency admissions in Boston, MA. J. Epidemiol. Community Health 60, 890–895. Zar, H.J., Madhi, S.A., Aston, S.J., Gordon, S.B., 2013. Pneumonia in low and middle income countries: progress and challenges. Thorax 68, 1052–1056. Zeng, J., Lu, C., Deng, Q., 2017. Prenatal exposure to diurnal temperature variation and early childhood pneumonia. J. Therm. Biol. 65, 105–112. Zhang, J.J., Smith, K.R., 2003. Indoor air pollution: a global health concern. Br. Med. Bull. 68, 209–225. Zhang, Y., Li, B., Huang, C., Yang, X., Qian, H., Deng, Q., et al., 2013. Ten cities crosssectional questionnaire survey of children asthma and other allergies in China. Chin. Sci. Bull. 58, 4182–4189. Zheng, X., Qian, H., Zhao, Y., Shen, H., Zhao, Z., Sun, Y., et al., 2013. Home risk factors for childhood pneumonia in Nanjing, China. Chin. Sci. Bull. 58, 4230–4236.
5. Conclusions Pneumonia continues to be a major public health challenge in young preschool children in China. Our findings suggested that “double” exposure to high level of outdoor particulate air pollution and indoor air new furniture/redecoration pollution from renovation was associated with the high prevalence of early childhood pneumonia in China. Our finding provides an implication to prevent pneumonia in children by taking effective measures to reduce the exposure to outdoor PM10 and to avoid the indoor renovation for expected children, especially infants. Conflicts of interest None. Acknowledgments The research was supported by the National Natural Science Foundation of China (No. 51576214 and 21777193) and Key Research and Development Program of Hunan Province (No. 2017SK2091). We are particularly indebted to the children, their parents and the kindergartens for their time and enthusiastic participation. Appendix A. Supplementary data Supplementary data related to this article can be found at http://dx. doi.org/10.1016/j.atmosenv.2017.11.043. References Accinelli, R.A., Leon-Abarca, J.A., Gozal, D., 2017. Ecological study on solid fuel use and pneumonia in young children: a worldwide association. Respirology 22, 149–156. Bhutta, Z.A., Das, J.K., Walker, N., Rizvi, A., Campbell, H., Rudan, I., et al., 2013. Interventions to address deaths from childhood pneumonia and diarrhoea equitably: what works and at what cost? Lancet 381, 1417–1429. Braga, A.L., Saldiva, P.H., Pereira, L.A., Menezes, J.J., Conceição, G.M., Lin, C.A., et al., 2001. Health effects of air pollution exposure on children and adolescents in São Paulo, Brazil. Pediatr. Pulmonol. 31, 106–113. Coombs, K.C., Chew, G.L., Schaffer, C., Ryan, P.H., Brokamp, C., Grinshpun, S.A., et al., 2016. Indoor air quality in green-renovated vs. non-green low-income homes of children living in a temperate region of US (Ohio). Sci. Total Environ. 554–555, 178–185. Dai, H., Jing, S., Wang, H., Ma, Y., Li, L., Song, W., et al., 2016. Voc characteristics and inhalation health risks in newly renovated residences in Shanghai, China. Sci. Total Environ. 577, 73–83. Deng, Q., Lu, C., Norbäck, D., Bornehag, C.-G., Zhang, Y., Liu, W., et al., 2015a. Early life exposure to ambient air pollution and childhood asthma in China. Environ. Res. 143, 83–92. Deng, Q., Lu, C., Ou, C., Liu, W., 2015b. Effects of early life exposure to outdoor air pollution and indoor renovation on childhood asthma in China. Build. Environ. 93, 84–91. Deng, Q., Lu, C., Li, Y., Sundell, J., Norbäck, D., 2016a. Exposure to outdoor air pollution during trimesters of pregnancy and childhood asthma, allergic rhinitis, and eczema. Environ. Res. 150, 119–127. Deng, Q., Lu, C., Ou, C., Chen, L., Yuan, H., 2016b. Preconceptional, prenatal and postnatal exposure to outdoor and indoor environmental factors on allergic diseases/ symptoms in preschool children. Chemosphere 152, 459–467. Deng, Q., Lu, C., Li, Y., Chen, L., He, Y., Sundell, J., Norbäck, D., 2017. Association of prenatal exposure to industrial air pollution with onset of early childhood ear infection in China. Atmos. Environ. 157, 18–26. Dherani, M., Pope, D., Mascarenhas, M., Smith, K.R., Weber, M., Bruce, N., 2008. Indoor air pollution from unprocessed solid fuel use and pneumonia risk in children aged under five years: a systematic review and meta-analysis. Bull. World Health Org. 86, 390–398C. DiFranza, J.R., Aligne, C.A., Weitzman, M., 2004. Prenatal and postnatal environmental tobacco smoke exposure and children's health. Pediatrics 113, 1007–1015. Dong, G.H., Qian, Z.M., Wang, J., Trevathan, E., Liu, M.M., Wang, D., et al., 2014. Home renovation, family history of atopy, and respiratory symptoms and asthma among children living in China. Am. J. Public Health 104, 1920–1927. Du, Z., Mo, J., Zhang, Y., Xu, Q., 2014. Benzene, toluene and xylenes in newly renovated homes and associated health risk in Guangzhou, China. Build. Environ. 72, 75–81.
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Contents lists available at ScienceDirect
Atmospheric Environment journal homepage: www.elsevier.com/locate/atmosenv
Outdoor particulate air pollution and indoor renovation associated with childhood pneumonia in China
T
Wei Jianga,1, Chan Lua,1, Yufeng Miaoa, Yuguang Xianga, Lv Chenb, Qihong Denga,b,c,d,∗ a
School of Energy Science and Engineering, Central South University, Changsha, Hunan, China XiangYa School of Public Health, Central South University, Changsha, Hunan, China c Institute of Environmental Health, Central South University, Changsha, Hunan, China d Collaborative Innovation Center of Building Energy Conservation & Environmental Control, Hunan, China b
G RA P H I C A L AB S T R A C T
A R T I C L E I N F O
A B S T R A C T
Keywords: Pneumonia Ambient air pollution Indoor air pollution New furniture Redecoration Urbanization
Background: Pneumonia is a common early-childhood respiratory infection that leads to long-term health impacts, but its risk factors remain unclear. Objective: To examine the association between early life exposure to both outdoor and indoor air pollution and childhood pneumonia. Methods: We conducted a retrospective cohort study of 2598 children aged 3–6 years in Changsha, China (20112012). Children's life-time prevalence of pneumonia and exposure to indoor air pollution related to home renovation were surveyed by a questionnaire answered by the parents. Children's exposure to outdoor air pollution, including nitrogen dioxide (NO2), sulfur dioxide (SO2), and particulate matter with an aerodynamic diameter ≤ 10 μm (PM10), was estimated using the measured concentrations at monitoring stations. Association between childhood pneumonia and exposure to indoor and outdoor air pollution during both prenatal and postnatal periods were examined by using logistic regression model in terms of odds ratio (OR) and 95% confidence interval (CI). Results: Life-time prevalence of pneumonia in preschool children in Changsha is high, up to 38.6%.We found that childhood pneumonia was associated with postnatal exposure to outdoor particulate air pollutant PM10, adjusted OR (95% CI) = 1.26 (1.00–1.57) for per 6 μg/m3 increase in the concentration. Pneumonia was also associated with postnatal exposure to indoor renovation, adjusted OR (95% CI) = 1.30 (1.02–1.64) for new furniture and 1.30 (1.00–1.69) for redecoration. Combined exposure to outdoor high PM10 and indoor renovation significantly increased the pneumonia risk. Sensitivity analysis indicated that the association was heterogeneous in different subgroups, but stronger in male and younger children.
∗
1
Corresponding author. XiangYa School of Public Health, Central South University, Changsha 410083, Hunan, China. E-mail address: [email protected] (Q. Deng). These authors contributed equally to this work.
https://doi.org/10.1016/j.atmosenv.2017.11.043 Received 12 April 2017; Received in revised form 20 November 2017; Accepted 26 November 2017 Available online 27 November 2017 1352-2310/ © 2017 Elsevier Ltd. All rights reserved.
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Conclusion: High prevalence of childhood pneumonia in China may be associated with postnatal exposure to ambient particulate air pollution and house renovation.
1. Introduction
response rate) but excluded: (1) 745 children in kindergartens with response rate < 50%, as the children are mainly from the rural areas and thus their exposure during pregnancy cannot be estimated; (2) 162 children with low birth weight (< 2.5 kg) or preterm birth (< 37 weeks of gestation) and 10 children with multiple births, as these conditions may confound the effect of air pollution; (3) 80 children younger than 3 and older than 6, because they are too few; (4) 302 children without information about pneumonia. Totally, the 2598 complete data sets were entered into a database.
Pneumonia is one of the most common reasons for hospital admission and the first leading cause of death in children (Liu et al., 2012; Walker et al., 2013). Pneumonia accounted for 15 percent of all underfive deaths and killed 920,000 children in 2015; 99% of deaths occurred in low and middle income countries (Zar et al., 2013). In addition, childhood pneumonia has wide-ranging complications and sequelae in later life, which not only has a crippling effect on child's development and quality of life but also results in heavy economic burden for both family and society (Le et al., 2014; Walker et al., 2013). Most pneumonia are preventable (Bhutta et al., 2013), and therefore there is a critical need to investigate the main risk factors of pneumonia so as to provide more effective preventative strategies. Childhood clinical pneumonia is a complex disease caused by a combination of host, infection and the environment factors (Rudan et al., 2008). Although host and infection factors strongly influence the risk of pneumonia, environmental factors have been shown to be a significant risk factor for the development of pneumonia (Miao et al., 2017; Zeng et al., 2017). Recent studies have suggested that outdoor air pollution was associated with childhood pneumonia, but mainly focused on the association between short-term exposure and emergency department visits for pneumonia (Fusco et al., 2001; Neupane et al., 2010). The effect of long-term exposure to air pollution on childhood pneumonia is unclear and has never been investigated. On the other hand, indoor air pollution may have a greater impact than outdoor air pollution because children spend 90% of their time indoors (Nazaroff and Goldstein, 2015; Zhang and Smith, 2003). With the rapid economic growth and urbanization process in China during the past decade, a huge amount of people, particularly the new couples and expectant parents, have moved into new buildings with redecoration and new furniture (Deng et al., 2015b). The new house and house renovation have become a major source of indoor air pollution and their impact on the health of children who was born or will be born is an increasing concern in China (Gao et al., 2014). However, there is a lack of examination for the risk of childhood pneumonia due to indoor air pollution generated by renovation. Recently, early-life exposure to air pollution has attracted considerable attention, as it influences developmental plasticity and hence leads to later development of a variety of complex diseases (Deng et al. 2016a,b, 2017; Gluckman et al., 2008; Suk et al., 2016). Therefore, our study aims to examine childhood pneumonia risk due to early life exposure to outdoor air pollution and indoor renovation in China during both prenatal and postnatal periods, so as to identify the susceptible windows of exposure and key components of air pollution in the development of pneumonia. Accordingly, we carried out a cohort study in Changsha, a part of nationwide multi-center “China-Children-HomesHealth (CCHH)” study (Zhang et al., 2013).
2.2. Exposure timing windows Children's exposure was divided into prenatal and postnatal periods. The prenatal exposure referred to the exposure during the entire pregnancy that was defined as from the first month to the last month of pregnancy, and the postnatal exposure was defined as the exposure during the period from the first year to the past year. 2.3. Exposure to ambient air pollution Ambient air pollution was characterized by three criteria pollutants: sulfur dioxide (SO2), nitrogen dioxide (NO2), and particulate matter ≤ 10 μm in diameter (PM10). We obtained daily average concentrations of the air pollutants from 7 municipal air quality monitoring stations. Children's daily exposure were estimated by air pollutant concentrations at the kindergartens that were projected from those at the stations by using an inverse distance weight (IDW) method (Deng et al., 2015a). Prenatal exposure was calculated as average of the monthly mean concentrations of PM10, SO2 and NO2 during the full gestational months. Postnatal exposure was calculated as the average of the monthly mean concentrations of air pollutants during all months from the first year to the past year. 2.4. Exposure to indoor renovation Children's exposure to indoor renovation in terms of new furniture and redecoration was assessed by the questionnaire survey. Exposure to new furniture was assessed by the question: “Did you install new furniture in your house (Yes/No/Don't know)?” and if yes, “When did you install the new furniture (During pregnancy/First year of life/After first year of life)?” Exposure to redecoration was assessed by another question:“Did you redecorate your house (Yes/No/Don't know)?” and if yes, “When did you redecorate your house (During pregnancy/First year of life/After first year of life)?” 2.5. Health outcome
2. Method
The health outcome of the questionnaire, lifetime prevalence of pneumonia, was based on the answer to the question: “Has your child ever been diagnosed with pneumonia?”
2.1. Study population
2.6. Confounding covariates
We conducted a survey for respiratory disease in children in Changsha during the period from September 2011 to January 2012. The study protocol and questionnaire were described elsewhere (Deng et al., 2015a). We distributed 4988 questionnaires to the children at 36 randomly selected kindergartens. Children were instructed to have the questionnaire completed by parents and to return it to kindergartens within one week. We received 3897 completed questionnaires (78%
Potential confounding variables are also obtained from the questionnaires that include: (1) child-related covariates included sex, age, birth season, breast-feeding, day-care attendance; (2) parent-related covariates included parental atopy and socioeconomic status (SES) indicating by housing size; (3) residential-related covariates included environmental tobacco smoke (ETS), visible mold/damp stains at home, and window condensation in winter. It was identified that these 77
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41.9%) than that during prenatal period (38.2% and 35.0%). The association between exposure to outdoor air pollutants and childhood pneumonia was shown in Table 4. We found that the pneumonia was not associated with SO2 and NO2, but only significantly associated with postnatal exposure to PM10 with adjusted OR (95% CI) = 1.26 (1.00–1.57) for per IQR increase (6 μg/m3). The association was robust and consistent after adjustment for multi-windows, and further adjustment for multi-pollutants (Table S1, as shown in supplemental materials). The association between exposure to indoor renovation and childhood pneumonia was shown in Table 5. Childhood pneumonia was also only significantly associated with postnatal exposure to new furniture and redecoration with adjusted OR (95% CI) = 1.30 (1.02–1.64) and 1.30 (1.00–1.69) respectively. The association between postnatal exposure to combined outdoor PM10 and indoor renovation and childhood pneumonia was presented in Table 6. We found that exposure to both outdoor high PM10 and indoor renovation posed the highest and significant risk, as compared to the risk of exposure to low PM10 in outdoors and no renovation in indoors. Fig. 1 shows the sensitivity analysis of the association between childhood pneumonia and postnatal exposure to outdoor PM10 and indoor renovation in different subgroups stratified by the significant covariates shown in Table 1. We found that the association was heterogeneous, but stronger in male and younger children and also in children without parental atopy and living in houses without mold/ dampness.
confounders were related to childhood pneumonia and may influence the affect estimates. Children's birth season was divided into Spring (March to May), Summer (June to August), Autumn (September to November) and winter (December to February). Parental atopy was defined as a history of maternal or paternal asthma, allergic rhinitis and eczema. 2.7. Statistical analysis Multiple logistic regression analysis was implemented to evaluate the association between pneumonia in children and their exposure to outdoor air pollution or indoor renovation during prenatal and postnatal periods adjusting for covariates. Association was calculated as odds ratio (OR) with 95% confidence interval (95% CI) and the value p < 0.05 was considered to be statistically significant. Outdoor air pollutants were entered into the regression model as continuous variables, and their risks of pneumonia were estimated by an interquartile range (IQR) increase in exposure levels. A single-pollutant model was firstly examined, and then a multi-pollutant model was carried out to mutually adjust the effects of other air pollutants so as to obtain the independent association of each air pollutant with childhood pneumonia, and finally a multi-window model was investigated to further obtain the independent risk of exposure in prenatal or postnatal period (Deng et al., 2016a). Indoor new furniture and redecoration were entered into the model as categorical variables. In order to obtain the independent risk of exposure to indoor renovation during different periods, we divided the exposure into four mutually exclusive categories: not exposed in either prenatal or postnatal period (the reference category with OR = 1), exposed in prenatal but not postnatal period, exposed postnatal but not prenatal period, and exposed in both prenatal and postnatal periods. Furthermore, sensitivity analyses were conducted to examine the heterogeneity in different subgroups. All statistical analyses were performed by SPSS software (version 16.0, SPSS Inc, Chicago, USA).
Table 1 Covariates, demographic information and prevalence of pneumonia among children aged 3–6 years old (n = 2598). Number
(%)
Case
(%)
Total 2598 (100) 1004 (38.6) Child's Sex Boys 1399 (54) 571 (40.8) Girls 1199 (46) 433 (36.1) Birth season Spring 598 (23) 228 (38.1) Summer 744 (29) 278 (37.4) Autumn 666 (26) 258 (38.7) Winter 590 (23) 240 (40.7) Age 3 665 (26) 233 (35) 4 952 (37) 395 (41.5) 5 815 (31) 301 (36.9) 6 166 (6) 75 (45.2) Breast-feeding No 222 (9) 99 (44.6) Yes 2376 (91) 905 (38.1) Day-care attendance (years old) <3 615 (24) 250 (40.7) ≥3 1971 (76) 749 (38) Parental Parental atopy No 2214 (85) 826 37.3 Yes 340 (13) 167 49.1 Parental socioeconomic status (SES) by house size (m2) ≤75 836 (32) 306 (36.6) > 75 1732 (67) 690 (39.8) Residential Environmental tobacco smoke (ETS) at home No 864 (33) 329 (38.1) Yes 1734 (67) 675 (38.9) Visible mold/damp stains at home No 1985 (76) 742 (37.4) Yes 606 (23) 258 (42.6) Window condensation in winter No 1175 (45) 431 (36.7) Yes 1369 (53) 553 (40.4)
3. Results Of 2598 children, 1004 (38.6%) had a history of doctor-diagnosed pneumonia. Table 1 shows the demographics and lifetime prevalence of pneumonia stratified by covariates. In this study, 54% of the children were male and 46% were female. The children were born uniformly across the seasons and 91% were breast-fed. About 13% of the children's parents have atopic diseases. Two-third of the children lived in houses with ETS, 23% of the children in houses with visible mold and dampness, and half of the children in houses with window condensation during winter. We found that the prevalence was significantly associated with some child's, parental and residential factors: the prevalence is significantly higher in children who are male (p = 0.012), older (p = 0.010), without breast-feeding (p = 0.049) and with parental atopy (p = 0.0) and also higher for those living houses with visible mold/dampness (p = 0.020) and window condensation (p = 0.048). Children's exposure to outdoor air pollutants was summarized in Table 2. The average individual exposure to the classic air pollutants (PM10 and SO2) were substantially decreased from prenatal levels of 110 μg/m3 and 82 μg/m3 to postnatal 93 μg/m3 and 51 μg/m3, but exposure to the traffic-related air pollutant (NO2) was slightly increased from prenatal 46 μg/m3 to postnatal 49 μg/m3. Children's exposure to indoor renovation was shown in Table 3. Very few families installed new furniture (7.4%) and redecorated their houses (3.1%) during pregnancy (prenatal), but 37.7% and 19.2% families respectively installed new furniture and redecorated their houses after the children were born (postnatal). Table 3 also showed the prevalence of pneumonia in the children living in these families. We found that the prevalence of childhood pneumonia for exposure to new furniture and redecoration was higher during postnatal period (40.8% and
p-value –
0.012
0.648
0.010
0.049
0.215
0.000
0.115
0.675
0.020
0.048
Sum of the number is not 2598 due to missing data. The values p < 0.05 were in bold.
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indoor new furniture/redecoration. We further observed that combined exposure to outdoor PM10 and indoor renovation significantly increased the risk of pneumonia in children. Our study protocol has several strengths. Firstly, we conducted a large cohort study in one city assessed by individual exposure using an inverse distance weighted (IDW) method, in contrast to limited previous analyses that have been conducted with small study populations and have focused largely on cross-sectional comparisons between different geographic regions. Secondly, we identified susceptible window of exposure and key component of air pollution in the development of childhood pneumonia by analysing its association with different air pollutants during different exposure periods. Thirdly, we investigated the association between the combined outdoor and indoor air pollution with childhood pneumonia. We found long-term postnatal exposure to particulate air pollutant (PM10) significantly increased the risk of pneumonia in children. Although no studies examined the risk of long-term exposure to ambient air pollution for childhood pneumonia, our finding is consistent with some short-term studies. Exposure to PM10 were found to be associated with increased risk of daily hospital admissions of pneumonia in children in Brazil (Braga et al., 2001) and Vietnam (Mehta et al., 2013). In addition, childhood pneumonia hospitalization was found to be significantly associated with exposure to coarse (PM10–2.5) and fine (PM2.5), and even ultrafine particles (Fusco et al., 2001; Yang et al., 2004; Zanobetti and Schwartz, 2006). Our findings were also supported by a recent case-crossover study in China (Duan et al., 2016), which found that high level PM2.5 increase the risk of hospitalization for pneumonia. We found an association between exposure to indoor new furniture/ redecoration and childhood pneumonia. Early childhood pneumonia has been found to be closely related to indoor environmental factors, but mainly for solid fuels (Accinelli et al., 2017; Dherani et al., 2008; Ram et al., 2014; Smith et al., 2011) and parental smoking or environmental tobacco smoke (ETS) (DiFranza et al., 2004; Suzuki et al., 2009). In China, due to the rapid economic growth during the past decades, children exposure to unprocessed solid fuels and ETS at home has been greatly reduced. However, due to the rapid urbanization progress, a huge number of people, especially the new couples and expectant parents, migrated into new buildings during the past decade (Du et al., 2014). The risk of renovation and new furniture to the children has rarely been investigated, but several studies found that indoor renovation or new furniture were associated with increased likelihood of respiratory symptoms, allergic rhinitis, asthma (Coombs et al., 2016; Dai et al., 2016; Deng et al., 2015b; Dong et al., 2014; Mendell, 2007). Our findings were supported by one recent populationbased cross-sectional study in Nanjing (Zheng et al., 2013), which found that new furniture and decorative materials were significantly associated with pneumonia among children. Our results indicated that childhood pneumonia is still serious in China. Our study observed that the lifetime prevalence incidence in Changsha is high up to 38.6% episodes, comparable the recent data in
Table 2 Statistics of exposure to outdoor air pollution among children aged 3–6years (n = 2598). Mean Prenatal PM10 110 SO2 82 NO2 46 Postnatal PM10 93 SO2 51 NO2 49
25th Percentile
50th Percentile
75th Percentile
IQR
103 62 40
108 75 45
115 98 52
12 36 12
90 42 43
93 49 49
96 57 55
6 15 12
PM10 (μg/m3) = particulate matter ≤ 10 μm in aerodynamic diameter; SO2 (μg/ m3) = sulfur dioxide; NO2 (μg/m3) = nitrogen dioxide; IQR = interquartile range. Table 3 Statistics of exposure to indoor renovation and pneumonia cases among children aged 3–6years (n = 2598).
Prenatal New furniture Redecoration Postnatal New furniture Redecoration
n (%)
Case (%)
191 (7) 80 (3)
73 (38.2) 28 (35.0)
980 (38) 499 (19)
400 (40.8) 209 (41.9)
Table 4 Odds ratio (95% CI) of childhood pneumonia for exposure to air pollution among children aged 3–6years (n = 2598). Multi-window modelb
Single-pollutant model
Prenatal PM10 SO2 NO2 Postnatal PM10 SO2 NO2
Crude
Adjusteda
1.04 (0.95, 1.14) 0.95 (0.85, 1.06) 0.87 (0.77, 0.98)*
0.93 (0.77, 1.12) 0.92 (0.76, 1.11) 0.86 (0.70, 1.04)
0.92 (0.76, 1.11) 0.77 (0.58, 1.02) 0.77 (0.50, 1.19)
1.13 (1.01, 1.26)* 1.04 (0.93, 1.16) 0.89 (0.76, 1.05)
1.26 (1.00, 1.57)* 1.05 (0.87, 1.26) 0.88 (0.70, 1.10)
1.26 (1.01, 1.59)* 1.28 (0.96, 1.70) 1.15 (0.69, 1.91)
OR (95%CI) was estimated for an IQR increase in PM10, SO2, and NO2. *p ≤ 0.05. a Single-pollutant model: adjustment for all the covariates in Table 1. b Multi-window model: further adjustment for the effects of the air pollutant in other window on the base of single-pollutant model.
4. Discussion In this population-based cohort study, we found that the lifetime prevalence of pneumonia in preschool children was significantly associated with postnatal exposure to particulate air pollutant PM10 and
Table 5 Odds ratio (95%CI) of childhood pneumonia for pre- and post-natal exposure to indoor renovation among children aged 3–6years (n = 2598).
New furniture
Redecoration
Prenatal
Postnatal
n (%)
Crude OR (95%CI)
Adjusted OR (95%CI)
No No Yes Yes No No Yes Yes
No Yes No Yes No Yes No Yes
1248 (48) 818 (31) 176 (7) 162 (6) 1689 (65) 481 (19) 121 (5) 18 (1)
1.00 1.26 1.30 1.03 1.00 1.20 1.05 1.66
1.00 1.30 1.24 0.92 1.00 1.30 1.14 0.64
*p ≤ 0.05. **p ≤ 0.01. a Adjustment for all the covariates in Table 1.
79
(1.05, 1.51)* (0.94, 1.79) (0.73, 1.45) (0.97, 1.47) (0.72, 1.54) (0.65, 4.19)
(1.02, 1.64)* (0.82, 1.88) (0.59, 1.45) (1.00, 1.69)* (0.71, 1.85) (0.16, 2.54)
a
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Table 6 Odds ratio (95% CI) of childhood pneumonia for combined postnatal exposure to outdoor PM10 and indoor new furniture/redecoration among children aged 3–6years (n = 2598).
Postnatal PM10 Low Low High High Postnatal PM10 Low Low High High
Postnatal New furniture No Yes No Yes Postnatal Redecoration No Yes No Yes
n (%)
Crude OR (95% CI)
Adjusted OR (95% CI)
782 475 836 505
1.00 1.14 (0.91, 1.45) 1.08 (0.88, 1.32) 1.27 (1.01, 1.60)*
1.00 1.13 (0.89, 1.44) 1.08 (0.88, 1.33) 1.27 (1.00, 1.60)*
1.00 0.89 (0.66, 1.20) 0.98 (0.83, 1.18) 1.47 (1.12, 1.92)**
1.00 0.86 (0.63, 1.16) 0.98 (0.82, 1.18) 1.46 (1.11, 1.93)**
(30) (18) (32) (19)
1027 (40) 230 (9) 1072 (41) 269 (10)
a
Low and high exposure of PM10 is indicated by the personal exposure ≤ and > median value. *p ≤ 0.05. **p ≤ 0.01. a Adjustment for all the covariates in Table 1.
Murta et al., 2016; Wang et al., 2014). A recent study further suggested that long-term VOCs inhalation even at low levels can caused oxidative stress and genotoxicity response in mice (Wang et al., 2013, 2014). There are some limitations of this study that should be acknowledged. The first limitation is the potential misclassification of exposure. We estimated children's daily exposure to ambient air pollution according to their exposure in kindergarten only. It will be much better if we could average the daily exposure according to the exposure in kindergarten during daytime and the exposure at home during nighttime. However, we didn't ask the children's home address in our questionnaire because it is a very sensitive and private question in China. However, the exposure assessment was reasonable by considering the situation in China that the parents usually enrolled their children in kindergarten nearest to their home and that mother usually worked near home or kindergartens. Secondly, we estimated children's prenatal exposure to ambient air pollution based on their mother's exposure, which is not the same to fetus's exposure or in-utero exposure. This exposure misclassification is an intrinsic limitation of our study, because the in-utero exposure has to be estimated by using the blood biomarkers (Madhloum et al., 2017). Thirdly, we didn't measure the indoor VOCs concentrations emitted from the new furniture and
other cities in China (Qu et al., 2017), that is much higher than 0.05 episodes in developed countries (Guan et al., 2010; Rudan et al., 2008; Walker et al., 2013). Our findings indicated that “double exposure” to the high level of ambient air pollution and high rate of house renovation in China may contribute to the high prevalence of childhood pneumonia. Although the exact mechanism is not well understood, the association between postnatal exposure to outdoor particulate air pollution and indoor renovation and lifetime prevalence of pneumonia in children is biologically plausible. On one hand, the infant and child's respiratory and immunological systems are developing and hence are easily affected by the detrimental health effect of air pollution. Especially, the infant and child's alveoli are developing fast after birth, and pneumonia is kind of infection in alveoli. On the other hand, it has been demonstrated that PM10 can produce a large quantity of reactive oxygen species which trigger the inflammatory processes in the respiratory tract (Li et al., 2003). Meanwhile, redecoration and new furniture in homes has led to elevated levels of indoor VOCs (Dai et al., 2016). Several recent in vitro studies also demonstrated that exposure to indoor relevant concentrations of VOCs increased the production of inflammatory cytokines in human lung epithelial cell lines by the induction of oxidative stress or inflammation (Mascelloni et al., 2015;
Fig. 1. Sensitivity analysis for the association between childhood pneumonia and postnatal exposure to outdoor PM10 and indoor new furniture/redecoration by the significant covariates (as shown in Table 1).
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redecoration. The association between childhood pneumonia and indoor VOCs concentrations will be much helpful and provide strong evidence to understand the health effect of new furniture and redecoration.
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5. Conclusions Pneumonia continues to be a major public health challenge in young preschool children in China. Our findings suggested that “double” exposure to high level of outdoor particulate air pollution and indoor air new furniture/redecoration pollution from renovation was associated with the high prevalence of early childhood pneumonia in China. Our finding provides an implication to prevent pneumonia in children by taking effective measures to reduce the exposure to outdoor PM10 and to avoid the indoor renovation for expected children, especially infants. Conflicts of interest None. Acknowledgments The research was supported by the National Natural Science Foundation of China (No. 51576214 and 21777193) and Key Research and Development Program of Hunan Province (No. 2017SK2091). We are particularly indebted to the children, their parents and the kindergartens for their time and enthusiastic participation. Appendix A. Supplementary data Supplementary data related to this article can be found at http://dx. doi.org/10.1016/j.atmosenv.2017.11.043. References Accinelli, R.A., Leon-Abarca, J.A., Gozal, D., 2017. Ecological study on solid fuel use and pneumonia in young children: a worldwide association. Respirology 22, 149–156. Bhutta, Z.A., Das, J.K., Walker, N., Rizvi, A., Campbell, H., Rudan, I., et al., 2013. Interventions to address deaths from childhood pneumonia and diarrhoea equitably: what works and at what cost? Lancet 381, 1417–1429. Braga, A.L., Saldiva, P.H., Pereira, L.A., Menezes, J.J., Conceição, G.M., Lin, C.A., et al., 2001. Health effects of air pollution exposure on children and adolescents in São Paulo, Brazil. Pediatr. Pulmonol. 31, 106–113. Coombs, K.C., Chew, G.L., Schaffer, C., Ryan, P.H., Brokamp, C., Grinshpun, S.A., et al., 2016. Indoor air quality in green-renovated vs. non-green low-income homes of children living in a temperate region of US (Ohio). Sci. Total Environ. 554–555, 178–185. Dai, H., Jing, S., Wang, H., Ma, Y., Li, L., Song, W., et al., 2016. Voc characteristics and inhalation health risks in newly renovated residences in Shanghai, China. Sci. Total Environ. 577, 73–83. Deng, Q., Lu, C., Norbäck, D., Bornehag, C.-G., Zhang, Y., Liu, W., et al., 2015a. Early life exposure to ambient air pollution and childhood asthma in China. Environ. Res. 143, 83–92. Deng, Q., Lu, C., Ou, C., Liu, W., 2015b. Effects of early life exposure to outdoor air pollution and indoor renovation on childhood asthma in China. Build. Environ. 93, 84–91. Deng, Q., Lu, C., Li, Y., Sundell, J., Norbäck, D., 2016a. Exposure to outdoor air pollution during trimesters of pregnancy and childhood asthma, allergic rhinitis, and eczema. Environ. Res. 150, 119–127. Deng, Q., Lu, C., Ou, C., Chen, L., Yuan, H., 2016b. Preconceptional, prenatal and postnatal exposure to outdoor and indoor environmental factors on allergic diseases/ symptoms in preschool children. Chemosphere 152, 459–467. Deng, Q., Lu, C., Li, Y., Chen, L., He, Y., Sundell, J., Norbäck, D., 2017. Association of prenatal exposure to industrial air pollution with onset of early childhood ear infection in China. Atmos. Environ. 157, 18–26. Dherani, M., Pope, D., Mascarenhas, M., Smith, K.R., Weber, M., Bruce, N., 2008. Indoor air pollution from unprocessed solid fuel use and pneumonia risk in children aged under five years: a systematic review and meta-analysis. Bull. World Health Org. 86, 390–398C. DiFranza, J.R., Aligne, C.A., Weitzman, M., 2004. Prenatal and postnatal environmental tobacco smoke exposure and children's health. Pediatrics 113, 1007–1015. Dong, G.H., Qian, Z.M., Wang, J., Trevathan, E., Liu, M.M., Wang, D., et al., 2014. Home renovation, family history of atopy, and respiratory symptoms and asthma among children living in China. Am. J. Public Health 104, 1920–1927. Du, Z., Mo, J., Zhang, Y., Xu, Q., 2014. Benzene, toluene and xylenes in newly renovated homes and associated health risk in Guangzhou, China. Build. Environ. 72, 75–81.
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