Meteorological parameters and pollutants on asthma exacerbation in Bangalore, India - an ecological retrospective time-series study

Synergistic health effects of air pollution, temperature, and pollen exposure: a systematic review of epidemiological evidence

BACKGROUND

Exposure to heat, air pollution, and pollen are associated with health outcomes, including cardiovascular and respiratory disease. Studies assessing the health impacts of climate change have considered increased exposure to these risk factors separately, though they may be increasing simultaneously for some populations and may act synergistically on health. Our objective is to systematically review epidemiological evidence for interactive effects of multiple exposures to heat, air pollution, and pollen on human health.

METHODS

We systematically searched electronic literature databases (last search, April 29, 2019) for studies reporting quantitative measurements of associations between at least two of the exposures and mortality from any cause and cardiovascular and respiratory morbidity and mortality specifically. Following the Navigation Guide systematic review methodology, we evaluated the risk of bias of individual studies and the overall quality and strength of evidence.

RESULTS

We found 56 studies that met the inclusion criteria. Of these, six measured air pollution, heat, and pollen; 39 measured air pollution and heat; 10 measured air pollution and pollen; and one measured heat and pollen. Nearly all studies were at risk of bias from exposure assessment error. However, consistent exposure-response across studies led us to conclude that there is overall moderate quality and sufficient evidence for synergistic effects of heat and air pollution. We concluded that there is overall low quality and limited evidence for synergistic effects from simultaneous exposure to (1) air pollution, pollen, and heat; and (2) air pollution and pollen. With only one study, we were unable to assess the evidence for synergistic effects of heat and pollen.

CONCLUSIONS

If synergistic effects between heat and air pollution are confirmed with additional research, the health impacts from climate change-driven increases in air pollution and heat exposure may be larger than previously estimated in studies that consider these risk factors individually.

Association between air pollutants and outpatient and emergency hospital visits for childhood asthma in Shenyang city of China

Effects of air pollution on asthma vary in different study areas, and long-term time series research on the effects of air pollution on asthma outpatients and emergency hospital visits has not been conducted in Northeast China. We assessed the impact of air pollutants on the risk of asthma outpatients and emergency hospital visits in Shenyang, China. A distributed lag non-linear model with a Poisson regression was used to assess the short-term effects of air pollutants on asthma outpatient and emergency hospital visits between January 1, 2013 and December 31, 2017. Confounding factors were adjusted using natural cubic splines. Ozone (O₃), carbon monoxide (CO), and suspended particulates < 10 μm in aerodynamic diameter (PM₁₀) were positively associated with the number of asthma hospital visits. The largest cumulative effects of O₃, CO, and PM₁₀ on hospital visits were on lag day 2 (RR = 1.163, 95% CI 1.051-1.287) for 0-5-year-old childhood asthma, on lag day 3 (RR = 1.386, 95% CI 1.136-1.69) for asthma in winter, and on lag day 10 (RR = 1.148, 95% CI 0.942-1.399) for female asthma, respectively. The cumulative effect of air pollution represented by the air quality index (AQI) was largest on lag day 10 for 0-5-year-old childhood asthma with an increase of 28.6% (95% CI 6.5-55.4) hospital visits every IQR increment of the AQI. CO, O₃, and PM₁₀ were the main air pollutants in Shenyang city. Children with bronchitis asthma were more vulnerable to air pollution during the cold season.

Incidence of the Acute Symptom of Chronic Periodontal Disease in Patients Undergoing Supportive Periodontal Therapy: A 5-Year Study Evaluating Climate Variables

Although patients under supportive periodontal therapy (SPT) have a stable periodontal condition, the acute symptom of chronic periodontal disease occasionally occurs without a clear reason. Therefore, in the present study, to obtain a better understanding of this relationship in patients undergoing SPT, we hypothesized that the acute symptom of chronic periodontal disease might be affected by climate factors. We conducted a questionnaire study and carried out oral examinations on patients undergoing SPT who had been diagnosed as having the acute symptom of chronic periodontal disease. We collected climate data from the local climate office in Okayama city, Japan. We predicted parameters that affect the acute symptom of chronic periodontal disease with unidentified cause and divided patients into high and low groups in terms of climate predictors. Then we defined the cut-off values of parameters showing significant differences in the incidence of the acute symptom of chronic periodontal disease. The incidence of the acute symptom of chronic periodontal disease with unidentified cause was significantly different when the cases were classified according to the maximum hourly decrease in barometric pressure (1.5 and 1.9 hPa) (p = 0.04 and p = 0.03, respectively). This suggests that climate variables could be predictors of the acute symptom of chronic periodontal disease. Therefore, gaining a better understanding of these factors could help periodontal patients undergoing SPT prepare to avoid the acute symptom of chronic periodontal disease.

The effect and burden modification of heating on adult asthma hospitalizations in Shijiazhuang: a time-series analysis

Background

Previous studies have found associations between asthma morbidity and air pollution especially in young population, (PLoS One 12:e0180522, 2017; Can J Public Health 103:4-8, 2012; Environ Health Perspect 118:449-57, 2010; Am J Respir Crit Care Med 182:307-16, 2010; J Allergy Clin Immunol 104:717-22, 2008; J Allergy Clin Immunol 104:717-22, 1999; Environ Res 111:1137-47, 2011) but most of them were conducted in areas with relatively low air pollutant level. Moreover, very few studies have investigated the effect and burden modification of heating season during which the ambient air pollution level is significantly different from that during non-heating season in north China.

Objectives

This study aimed to evaluate the effect and burden modification of heating on short-term associations between adult asthma hospitalizations and ambient air pollution in the north China city of Shijiazhuang.

Methods

Generalized additive models combined with penalized distributed lag nonlinear models were used to model associations between daily asthma hospitalizations and ambient air pollutants from 1 January 2013 to 16 December 2016 in Shijiazhuang city, adjusting for long-term and seasonality trend, day of week, statutory holiday, daily mean air pressure and temperature. Attributable risks were calculated to evaluate the burden of asthma hospitalizations due to air pollutants exposure. The effect of pollutants on hospitalization and the attributable measures were estimated in heating and non-heating season separately and the comparisons between the two seasons were conducted.

Results

All pollutants demonstrated positive and significant impacts on asthma hospitalizations both in heating season and non-heating season, except for O₃ in heating season where a negative association was observed. However, the differences of the pollutant-specific effects between the two seasons were not significant. SO₂ and NO₂ exposure were associated with the heaviest burden among all pollutants in heating season; meanwhile, PM₁₀ and PM_2.5 were associated with the heaviest burden in heating season.

Conclusions

In conclusion, we found evidence of the effect of ambient air pollutants on asthma hospitalizations in Shijiazhuang. The central heating period could modify the effects in terms of attributable risks. The disease burden modification of heating should be taken into consideration when planning intervention measures to reduce the risk of asthma hospitalization.

Effects of Meteorological Factors on Hospitalizations in Adult Patients with Asthma: A Systematic Review

Background

Environmental factors such as weather variables contribute to asthma exacerbation. The impact of meteorological factors on asthma-related hospital admissions (HAs) or emergency department visits (EDVs) has been assessed in the literature. We conducted a systematic review to establish a conclusion of whether these findings from the literature are consistent and generalizable or if they vary significantly by certain subgroups.

Objective

This study aims to review the effect of meteorological variables on asthma HAs and EDVs in adults, to identify knowledge gaps and to highlight future research priorities.

Method

A systematic search was conducted in electronic databases such as PubMed, Embase, and CINAHL. All studies published in English were screened and included if they met the eligibility criteria. Two independent reviewers assessed the quality of the studies and extracted the data. The available evidence was summarized and presented using a harvest plot.

Results

Our initial search returned a total of 3887 articles. After screening titles, abstracts, and full texts, 16 studies were included. Thirty-one percent of the included studies (5/16) found that temperature was the only factor associated with asthma hospitalization or EDVs. Six studies (37%) found that both temperature and relative humidity were associated with HAs. Four studies (25%) identified thunderstorms as a possible factor associated with asthma hospitalization in adults.

Conclusion

Our review suggests that HAs and EDVs due to asthma are associated with many meteorological factors. Among the articles included in this review, changing temperature is the most commonly studied variable. We did not find studies that measured barometric pressure, weather phenomena, or the effect of tornados. To develop effective strategies to protect subjects at risk, further studies are required.

The cumulative effect of air pollutants on the acute exacerbation of COPD in Shanghai, China

BACKGROUND

Epidemiologic studies have shown the effect of air pollutants on acute exacerbation of chronic obstructive pulmonary disease (AECOPD). However, little is known regarding the dose-response relationship. This study aimed to investigate the cumulative effect of air pollutants on AECOPD.

METHODS

We collected 101 patients with AECOPD from November 2010 through August 2011 in Shanghai. Multiple logistic regression was used to estimate associations between air pollutants and AECOPD. Poisson regression was then applied to determine the cumulative effect of air pollutants including particulate matter 10 (PM10), PM2.5, nitrogen dioxide (NO₂), sulphur dioxide (SO₂) and ozone (O₃) on AECOPD, of which the seasonal variation was further explored.

RESULTS

The monthly episodes of AECOPD were associated with the concentrations of PM2.5 (r=0.884, p<0.05) and NO₂ (r=0.763, p<0.05). The cutoff value of PM2.5 and NO₂ for predicting AECOPD was 83.0μg/m³ and 53.5μg/m³, respectively. It showed that per 10μg/m³ increment in PM2.5 increased the relative risks (RR) for AECOPD was 1.09 with 3days cumulative effect in cold season, whereas 7days in warm season. The RR for AECOPD for per 10μg/m³ increment in NO₂ was 1.07, with a 5-day cumulative effect without seasonal variation.

CONCLUSIONS

High consecutive levels of PM2.5 and NO₂ increase the risk of developing AECOPD. Cumulative effect of PM2.5 and NO₂ appears before the exacerbation onset. These gradations were more evident in the PM2.5 during different seasons.