[Contribution of case-crossover design to the analysis of short-term health effects of air pollution: reanalysis of air pollution and health data]

Effect of Air Pollution and Hospital Admission: A Systematic Review

IntroductionMany epidemiological studies have demonstrated associations between air pollution levels and human health in terms of hospital admissions. The aim of this paper is to gather evidence concerning air pollution effects on the risk of hospital admission. We hypothesised that increase in: particulate matter (PM), ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), and sulphur dioxide (SO2) levels would be associated with the increasing trend of hospital admission.MethodsA systematic review of literature was carried out. Literature search was done in Sage, Ovid Medline, Science Direct, Wiley and ProQuest from 2010 to 2016 using keywords "hospital admission and air pollution". Studies of any relevant design were included if they presented original data, included at least one analysis where hospital admission was the specific outcome, and one or more of the following exposures were investigated: PM, O3, CO, NO2 and SO2.ResultsA total of 175 potential studies were identified by the search. Twenty two studies qualified for the review. Air pollution was noted to have an excessive risk of 3.46 (95%CI, 1.67, 5.27) of total hospital admissions. Cardiovascular admission was noted to have an increased risk of hospitalization for PM2.5 of 1.5 to 2.0; PM10 (1.007 to 2.7); NO2 (1.04 to 1.17) and SO2 (1.007). For respiratory admission, PM2.5 can caused an increased risk of hospitalization by 1.1 to 1.8; PM10 (1.007 to 1.13); NO2 (1.08 to 1.94) and SO2 (1.02). While O3 have minimal effect on COPD and stroke, CO does not influence in the effect of these hospitalization.ConclusionThe exposure to air pollutants confers an increased risk of admission of several disease. Our findings call for greater awareness of environmental protection and the implementation of effective measures to improve the quality of air, which may reduce the risks of adverse effects on the population's health.

Effect of Air Pollution and Hospital Admission: A Systematic Review

Introduction:

Many epidemiological studies have demonstrated associations between air pollution levels and human health in terms of hospital admissions. The aim of this paper is to gather evidence concerning air pollution effects on the risk of hospital admission. We hypothesised that increase in: particulate matter (PM), ozone (O₃), carbon monoxide (CO), nitrogen dioxide (NO₂), and sulphur dioxide (SO₂) levels would be associated with the increasing trend of hospital admission.

Methods:

A systematic review of literature was carried out. Literature search was done in Sage, Ovid Medline, Science Direct, Wiley, and ProQuest from 2010 to 2016 using keywords “hospital admission and air pollution”. Studies of any relevant design were included if they presented original data, included at least one analysis where hospital admission was the specific outcome, and one or more of the following exposures were investigated: PM, O₃, CO, NO₂ and SO₂.

Results:

A total of 175 potential studies were identified by the search. Twenty-two studies qualified for the review. Air pollution was noted to have an excessive risk of 3.46 (95% CI, 1.67, 5.27) of total hospital admissions. Cardiovascular admission was noted to have an increased risk of hospitalization for PM_2.5 of 1.5 to 2.0; PM₁₀ (1.007 to 2.7); NO₂ (1.04 to 1.17) and SO₂ (1.007). For respiratory admission, PM_2.5 can caused an increased risk of hospitalization by 1.1 to 1.8; PM₁₀ (1.007 to 1.13); NO₂ (1.08 to 1.94) and SO₂ (1.02). While O₃ have minimal effect on COPD and stroke, CO does not influence in the effect of these hospitalization.

Conclusion:

The exposure to air pollutants confers an increased risk of admission of several disease. Our findings call for greater awareness of environmental protection and the implementation of effective measures to improve the quality of air, which may reduce the risks of adverse effects on the population’s health.

Neighbourhood Characteristics and Long-Term Air Pollution Levels Modify the Association between the Short-Term Nitrogen Dioxide Concentrations and All-Cause Mortality in Paris

Background

While a great number of papers have been published on the short-term effects of air pollution on mortality, few have tried to assess whether this association varies according to the neighbourhood socioeconomic level and long-term ambient air concentrations measured at the place of residence. We explored the effect modification of 1) socioeconomic status, 2) long-term NO₂ ambient air concentrations, and 3) both combined, on the association between short-term exposure to NO₂ and all-cause mortality in Paris (France).

Methods

A time-stratified case-crossover analysis was performed to evaluate the effect of short-term NO₂ variations on mortality, based on 79,107 deaths having occurred among subjects aged over 35 years, from 2004 to 2009, in the city of Paris. Simple and double interactions were statistically tested in order to analyse effect modification by neighbourhood characteristics on the association between mortality and short-term NO₂ exposure. The data was estimated at the census block scale (n=866).

Results

The mean of the NO₂ concentrations during the five days prior to deaths were associated with an increased risk of all-cause mortality: overall Excess Risk (ER) was 0.94% (95%CI=[0.08;1.80]. A higher risk was revealed for subjects living in the most deprived census blocks in comparison with higher socioeconomic level areas (ER=3.14% (95%CI=[1.41-4.90], p<0.001). Among these deprived census blocks, excess risk was even higher where long-term average NO₂ concentrations were above 55.8 μg/m³ (the top tercile of distribution): ER=4.84% (95%CI=[1.56;8.24], p for interaction=0.02).

Conclusion

Our results show that people living in census blocks characterized by low socioeconomic status are more vulnerable to air pollution episodes. There is also an indication that people living in these disadvantaged census blocks might experience even higher risk following short-term air pollution episodes, when they are also chronically exposed to higher NO₂ levels.