Long-term nitrogen dioxide exposure and cause-specific mortality in the U.S. Medicare population

Long-Term Exposure to Nitrogen Dioxide and Ozone and Mortality: Update of the WHO Air Quality Guidelines Systematic Review and Meta-Analysis

Objectives

We performed a systematic review and meta-analysis on long-term exposure to nitrogen dioxide (NO2) and ozone (O3) with mortality, to expand evidence that informed 2021 the WHO Air Quality Guidelines and guide the Health Risks of Air Pollution in Europe project.

Methods

We included cohorts investigating NO2 and O3 mortality from all-causes, respiratory diseases, chronic obstructive pulmonary disease (COPD), acute lower respiratory infections (ALRI); and NO2 mortality from circulatory, ischemic heart, cerebrovascular diseases and lung cancer. We pooled estimates by random-effects models and investigated heterogeneity. We assessed the certainty of the evidence using the Grading of Recommendations Assessment Development approach and Evaluation (GRADE).

Results

We selected 83 studies for NO2 and 26 for O3 for the meta-analysis. NO2 was associated with all outcomes, except for cerebrovascular mortality. O3 was associated with respiratory mortality following annual exposure. There was high heterogeneity, partly explained by region and pollutant levels. Certainty was high for NO2 with COPD and ALRI, and annual O3 with respiratory mortality.

Conclusion

An increasing body of evidence, with new results from countrywide areas and the Western Pacific, supports certainty, including new outcomes.

Combined health effects of air pollutant mixtures on respiratory mortality using BKMR in Hangzhou, China

Previous research on respiratory system mortality primarily focused on understanding their combined effects and have neglected the fact that air pollution mixtures are interrelated. This study used Bayesian kernel machine regression (BKMR) to analyze the relationship between air pollutant mixtures and respiratory mortality in Hangzhou, China from 2014 to 2018. The results showed a significant association between pollutant mixtures and respiratory system mortality primarily driven by PM2.5 and SO2. The joint exposure of air pollutants was positively correlated with respiratory system mortality at lag 01 and lag 02 days. The estimated joint effects of log-transformed mixture air pollution exposure on log-transformed respiratory system mortality increased from -0.02 (95% CI: -0.08-0.02) and -0.01 (95% CI: -0.05-0.04) at the 25th percentile to 0.06 (95% CI: 0.01-0.12) and 0.04 (95% CI: -0.001, 0.09) at the 75th percentile. Additionally, there was evidence of an interaction between O3 and PM10. This study confirms that exposure to multiple pollutants is a significant public health problem facing the Hangzhou population given the compounded effect proven with regression analysis, while furthermore, the control of PM2.5 and SO2 also represents a serious concern.Implications: Evidence indicates interactions between O3 and PM10. This study demonstrates that exposure to multiple pollutants exerts combined effects on the public health of the Hangzhou population, highlighting the importance of controlling PM2.5 and SO2.

Short-Term Exposure to Ambient Air Pollution and Antimicrobial Use for Acute Respiratory Symptoms

Importance

Ambient air pollution and antimicrobial resistance pose significant global public health challenges. It is not known whether ambient air pollution is associated with increased consumption of antimicrobials.

Objective

To assess whether a short-term association exists between ambient air pollution levels and antimicrobial consumption among the general population seeking primary care consultations for acute respiratory symptoms.

Design, Setting, and Participants

This 2-stage cross-sectional ecological time series analysis study using data on daily ambient air pollution and antimicrobial consumption was conducted in the 11 largest cities in Catalonia, Spain, from June 23, 2012, to December 31, 2019, among all inhabitants aged 12 years or older. Statistical analysis was performed from November 2022 to December 2023.

Exposures

Daily ambient air pollution (particulate matter of 10 μg/m3 [PM10], particulate matter of 2.5 μg/m3 [PM2.5], and nitrogen dioxide [NO2]).

Main Outcomes and Measures

The main outcome was antimicrobial consumption associated with primary care consultations for acute respiratory symptoms in the 30 days before and after the dispensing of the antimicrobial. Antimicrobial consumption was measured as defined daily doses (DDDs) per 1000 inhabitants per day.

Results

Among 1 938 333 inhabitants (median age, 48 years [IQR, 34-65 years]; 55% female participants), there were 8 421 404 antimicrobial dispensations, with a median of 12.26 DDDs per 1000 inhabitants per day (IQR, 6.03-15.32 DDDs per 1000 inhabitants per day). The median adjusted morbidity score was 2.0 (IQR, 1.0-5.0). For the 1 924 814 antimicrobial dispensations associated with primary care consultations for acute respiratory symptoms, there was a significant correlation between increases of 10 μg/m3 in the concentration of the 3 pollutants studied and heightened antimicrobial consumption at day 0 (PM10: relative risk [RR], 1.01 [95% CI, 1.01-1.02]; PM2.5: RR, 1.03 [95% CI, 1.01-1.04]; NO2: RR, 1.04 [95% CI, 1.03-1.05]). A delayed association emerged between increases in PM2.5 concentration and antimicrobial consumption between day 7 (RR, 1.00 [95% CI, 1.00-1.01]) and day 10 (RR, 1.00 [95% CI, 1.00-1.01]) after exposure.

Conclusions and Relevance

In this 2-stage cross-sectional study using ecological time series analysis, short-term exposure to air pollution was associated with increased antimicrobial use associated with primary care consultations for acute respiratory symptoms in the general population. This finding could contribute to informing policy decisions aimed at reducing air pollution and its associated risks, thereby promoting respiratory health and reducing antimicrobial use.

Evaluating the sensitivity of mortality attributable to pollution to modeling Choices: A case study for Colorado

We evaluated the sensitivity of estimated PM2.5 and NO2 health impacts to varying key input parameters and assumptions including: 1) the spatial scale at which impacts are estimated, 2) using either a single concentration-response function (CRF) or using racial/ethnic group specific CRFs from the same epidemiologic study, 3) assigning exposure to residents based on home, instead of home and work locations for the state of Colorado. We found that the spatial scale of the analysis influences the magnitude of NO2, but not PM2.5, attributable deaths. Using county-level predictions instead of 1 km2 predictions of NO2 resulted in a lower estimate of mortality attributable to NO2 by ∼ 50 % for all of Colorado for each year between 2000 and 2020. Using an all-population CRF instead of racial/ethnic group specific CRFs results in a 130 % higher estimate of annual mortality attributable for the white population and a 40 % and 80 % lower estimate of mortality attributable to PM2.5 for Black and Hispanic residents, respectively. Using racial/ethnic group specific CRFs did not result in a different estimation of NO2 attributable mortality for white residents, but led to ∼ 50 % lower estimates of mortality for Black residents, and 290 % lower estimate for Hispanic residents. Using NO2 based on home instead of home and workplace locations results in a smaller estimate of annual mortality attributable to NO2 for all of Colorado by 2 % each year and 0.3 % for PM2.5. Our results should be interpreted as an exercise to make methodological recommendations for future health impact assessments of pollution.

Air pollution and human health: a phenome-wide association study

OBJECTIVES

To explore the associations of long-term exposure to air pollution with onset of all human health conditions.

DESIGN

Prospective phenome-wide association study.

SETTING

Denmark.

PARTICIPANTS

All Danish residents aged ≥30 years on 1 January 2000 were included (N=3 323 612). After exclusion of individuals with missing geocoded residential addresses, 3 111 988 participants were available for the statistical analyses.

MAIN OUTCOME MEASURE

First registered diagnosis of every health condition according to the International Classification of Diseases, 10th revision, from 2000 to 2017.

RESULTS

Long-term exposure to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) were both positively associated with the onset of more than 700 health conditions (ie, >80% of the registered health conditions) after correction for multiple testing, while the remaining associations were inverse or insignificant. As regards the most common health conditions, PM2.5 and NO2 were strongest positively associated with chronic obstructive pulmonary disease (PM2.5: HR 1.06 (95% CI 1.05 to 1.07) per 1 IQR increase in exposure level; NO2: 1.14 (95% CI 1.12 to 1.15)), type 2 diabetes (PM2.5: 1.06 (95% CI 1.05 to 1.06); NO2: 1.12 (95% CI 1.10 to 1.13)) and ischaemic heart disease (PM2.5: 1.05 (95% CI 1.04 to 1.05); NO2: 1.11 (95% CI 1.09 to 1.12)). Furthermore, PM2.5 and NO2 were both positively associated with so far unexplored, but highly prevalent outcomes relevant to public health, including senile cataract, hearing loss and urinary tract infection.

CONCLUSIONS

The findings of this study suggest that air pollution has a more extensive impact on human health than previously known. However, as this study is the first of its kind to investigate the associations of long-term exposure to air pollution with onset of all human health conditions, further research is needed to replicate the study findings.

Long-term NO2 exposure and mortality: A comprehensive meta-analysis

In response to the World Health Organization's (WHO) revised annual mean nitrogen dioxide (NO2) standard from 40 μg/m3 to 10 μg/m3, reflecting the growing evidence linking long-term exposure to ambient NO2 and excess mortality, we conducted a comprehensive meta-analysis incorporating 11 new studies published since the WHO analysis. Our investigation involved a systematic search of three major databases (PubMed, Web of Science, and Scopus) for articles published until July 1, 2022. We employed random effects models to calculate summarized risk ratios (RR) along with 95% confidence intervals (CIs) for overall and subgroup analyses. Sensitivity analyses were conducted to assess result robustness, and publication bias was evaluated using funnel plots and Egger's linear regression. Out of 2799 identified articles, 56 were included in our meta-analysis. The findings indicate a heightened risk of all-cause, cardiovascular, and respiratory mortality associated with long-term exposure to ambient NO2, with pooled RR values of 1.03 (95% CI: 1.02, 1.05), 1.07 (95% CI: 1.04, 1.10), and 1.03 (95% CI: 1.02, 1.05) per 10 μg/m3 increase, respectively. Substantial heterogeneity (I2 = 84%-96%) among studies was observed. Subgroup analysis revealed significantly elevated RR values in Asia and Oceania (p-value <0.05). The aggregated values for all-cause and cardiovascular mortality were slightly larger than those reported in previous studies. Our study emphasizes the imperative to develop more patient cohorts and conduct age-refined analyses to explore the impact of existing chronic diseases on these associations. Further, additional cohorts in Asia and Oceania are essential to fortify evidence in these regions. Lastly, we recommend using fused multi-source data with higher spatiotemporal resolution for individual exposure representation to minimize heterogeneity among studies in future research.

All-Cause NO2-Attributable Mortality Burden and Associated Racial and Ethnic Disparities in the United States

Nitrogen dioxide (NO2) is a regulated pollutant that is associated with numerous health impacts. Recent advances in epidemiology indicate high confidence linking NO2 exposure with increased mortality, an association that recent studies suggest persists even at concentrations below regulatory thresholds. While large disparities in NO2 exposure among population subgroups have been reported, U.S. NO2-attributable mortality rates and their disparities remain unquantified. Here we provide the first estimate of NO2-attributable all-cause mortality across the contiguous U.S. (CONUS) at the census tract-level. We leverage fine-scale, satellite-informed, land use regression model NO2 concentrations and census tract-level baseline mortality data to characterize the associated disparities among different racial/ethnic subgroups. Across CONUS, we estimate that the NO2-attributable all-cause mortality is ∼170,850 (95% confidence interval: 43,970, 251,330) premature deaths yr-1 with large variability across census tracts and within individual cities. Additionally, we find that higher NO2 concentrations and underlying susceptibilities for predominately Black communities lead to NO2-attributable mortality rates that are ∼47% higher compared to CONUS-wide average rates. Our results highlight the substantial U.S. NO2 mortality burden, particularly in marginalized communities, and motivate adoption of more stringent standards to protect public health.

Long-term association of air pollution and incidence of lung cancer among older Americans: A national study in the Medicare cohort

BACKGROUND

Despite strong evidence of the association of fine particulate matter (PM2.5) exposure with an increased risk of lung cancer mortality, few studies had investigated associations of multiple pollutants simultaneously, or with incidence, or using causal methods. Disparities were also understudied.

OBJECTIVES

We investigated long-term effects of PM2.5, nitrogen dioxide (NO2), warm-season ozone, and particle radioactivity (PR) exposures on lung cancer incidence in a nationwide cohort.

METHODS

We conducted a cohort study with Medicare beneficiaries (aged ≥ 65 years) continuously enrolled in the fee-for-service program in the contiguous US from 2001 to 2016. Air pollution exposure was averaged across three years and assigned based on ZIP code of residence. We fitted Cox proportional hazards models to estimate the hazard ratio (HR) for lung cancer incidence, adjusted for individual- and neighborhood-level confounders. As a sensitivity analysis, we evaluated the causal relationships using inverse probability weights. We further assessed effect modifications by individual- and neighborhood-level covariates.

RESULTS

We identified 166,860 lung cancer cases of 12,429,951 studied beneficiaries. In the multi-pollutant model, PM2.5 and NO2 exposures were statistically significantly associated with increased lung cancer incidence, while PR was marginally significantly associated. Specifically, the HR was 1.008 (95% confidence interval [CI]: 1.005, 1.011) per 1-μg/m3 increase in PM2.5, 1.013 (95% CI: 1.012, 1.013) per 1-ppb increase in NO2, and 1.005 (0.999, 1.012) per 1-mBq/m3 increase in PR. At low exposure levels, all pollutants were associated with increased lung cancer incidence. Men, older individuals, Blacks, and residents of low-income neighborhoods experienced larger effects of PM2.5 and PR.

DISCUSSION

Long-term PM2.5, NO2, and PR exposures were independently associated with increased lung cancer incidence among the national elderly population. Low-exposure analysis indicated that current national standards for PM2.5 and NO2 were not restrictive enough to protect public health, underscoring the need for more stringent air quality regulations.

Exposure to low-level ambient air pollution and the relationship with lung and bladder cancer in older men, in Perth, Western Australia

BACKGROUND

Air pollution is a cause of lung cancer and is associated with bladder cancer. However, the relationship between air pollution and these cancers in regions of low pollution is unclear. We investigated associations between fine particulate matter (PM2.5), nitrogen dioxide, and black carbon (BC), and both these cancers in a low-pollution city.

METHODS

A cohort of 11,679 men ≥65 years old in Perth (Western Australia) were followed from 1996-1999 until 2018. Pollutant concentrations, as a time-varying variable, were estimated at participants' residential addresses using land use regression models. Incident lung and bladder cancer were identified through the Western Australian Cancer Registry. Risks were estimated using Cox proportional-hazard models (age as the timescale), adjusting for smoking, socioeconomic status, and co-pollutants.

RESULTS

Lung cancer was associated with PM2.5 and BC in the adjusted single-pollutant models. A weak positive association was observed between ambient air pollution and squamous cell lung carcinoma but not lung adenocarcinoma. Positive associations were observed with bladder cancer, although these were not statistically significant. Associations were attenuated in two-pollutant models.

CONCLUSION

Low-level ambient air pollution is associated with lung, and possibly bladder, cancer among older men, suggesting there is no known safe level for air pollution as a carcinogen.

Effect of Air Pollution on Heart Failure: Systematic Review and Meta-Analysis

BACKGROUND

Heart failure (HF) poses a significant global disease burden. The current evidence on the impact of air pollution on HF remains inconsistent.

OBJECTIVES

We aimed to conduct a systematic review of the literature and meta-analysis to provide a more comprehensive and multiperspective assessment of the associations between short- and long-term air pollution exposure and HF from epidemiological evidences.

METHODS

Three databases were searched up to 31 August 2022 for studies investigating the association between air pollutants (PM 2.5 , PM 10 , NO 2 , SO 2 , CO, O 3 ) and HF hospitalization, incidence, or mortality. A random effects model was used to derive the risk estimations. Subgroup analysis was conducted by geographical location, age of participants, outcome, study design, covered area, the methods of exposure assessment, and the length of exposure window. Sensitivity analysis and adjustment for publication bias were performed to test the robustness of the results.

RESULTS

Of 100 studies covering 20 countries worldwide, 81 were for short-term and 19 were for long-term exposure. Almost all air pollutants were adversely associated with the risk of HF in both short- and long-term exposure studies. For short-term exposures, we found the risk of HF increased by 1.8% [relative risk ( RR ) = 1.018 , 95% confidence interval (CI): 1.011, 1.025] and 1.6% (RR = 1.016 , 95% CI: 1.011, 1.020) per 10 - μ g / m 3 increment of PM 2.5 and PM 10 , respectively. HF was also significantly associated with NO 2 , SO 2 , and CO, but not O 3 . Positive associations were stronger when exposure was considered over the previous 2 d (lag 0-1) rather than on the day of exposure only (lag 0). For long-term exposures, there were significant associations between several air pollutants and HF with RR (95% CI) of 1.748 (1.112, 2.747) per 10 - μ g / m 3 increment in PM 2.5 , 1.212 (1.010, 1.454) per 10 - μ g / m 3 increment in PM 10 , and 1.204 (1.069, 1.356) per 10 -ppb increment in NO 2 , respectively. The adverse associations of most pollutants with HF were greater in low- and middle-income countries than in high-income countries. Sensitivity analysis demonstrated the robustness of our results.

DISCUSSION

Available evidence highlighted adverse associations between air pollution and HF regardless of short- and long-term exposure. Air pollution is still a prevalent public health issue globally and sustained policies and actions are called for to reduce the burden of HF. https://doi.org/10.1289/EHP11506.

Excess mortality associated with high ozone exposure: A national cohort study in China

Emerging epidemiological studies suggest that long-term ozone (O₃) exposure may increase the risk of mortality, while pre-existing evidence is mixed and has been generated predominantly in North America and Europe. In this study, we investigated the impact of long-term O₃ exposure on all-cause mortality in a national cohort in China. A dynamic cohort of 20882 participants aged ≥40 years was recruited between 2011 and 2018 from four waves of the China Health and Retirement Longitudinal Study. A Cox proportional hazard regression model with time-varying exposures on an annual scale was used to estimate the mortality risk associated with warm-season (April-September) O₃ exposure. The annual average level of participant exposure to warm-season O₃ concentrations was 100 μg m^-3 (range: 61-142 μg m^-3). An increase of 10 μg m^-3 in O₃ was associated with a hazard ratio (HR) of 1.18 (95% confidence interval [CI]: 1.13-1.23) for all-cause mortality. Compared with the first exposure quartile of O₃, HRs of mortality associated with the second, third, and highest exposure quartiles were 1.09 (95% CI: 0.95-1.25), 1.02 (95% CI: 0.88-1.19), and 1.56 (95% CI: 1.34-1.82), respectively. A J-shaped concentration-response association was observed, revealing a non-significant increase in risk below a concentration of approximately 110 μg m^-3. Low-temperature-exposure residents had a higher risk of mortality associated with long-term O₃ exposure. This study expands current epidemiological evidence from China and reveals that high-concentration O₃ exposure curtails the long-term survival of middle-aged and older adults.

Ambient NO2 hinders neutrophil extracellular trap formation in rats: Assessment of the role of neutrophil autophagy

NO₂ has been known to impair immunity and exacerbate susceptibility to infectious diseases. However, scant notice has been taken of the effect of NO₂ on neutrophils. Neutrophil extracellular traps (NETs) formation is necessary for NETosis development by neutrophils as an immune system against pathogens. By analyzing the morphology and signature components of NETs, we focused for the first time on finding that 10 ppm of NO₂ exposure for 15 consecutive days can hinder the formation of NETs. Next, we used NO₂ in vivo derivatives to probe the mechanism for NETs formation in vitro. Our findings showed that NO₂ suppression of respiratory burst levels and mitogen-activated protein kinase (MAPK)/Phosphoinositide 3-kinase (PI3K)-protein kinase B (AKT) signaling was related to NO₂ reduction in NETs formation. Inhibition of phorbol myristate acetate (PMA)-induced NETs formation by NO₂ hindered autophagy, as evidenced by increased mTOR protein expression, decreased LC3 protein expression, and reduced autophagic vesicles. By activating mTOR-mediated autophagy, rapamycin (Rapa) reduced the inhibition of PMA-induced NETs by NO₂. This study will provide valuable insights into the mechanisms of immunotoxicity of NO₂, new insights into the etiology of diseases linked to NETs formation, and a theoretical basis for protection against such illnesses.

The Impact of Long-Term Air Pollution Exposure on Type 1 Diabetes Mellitus-Related Mortality among U.S. Medicare Beneficiaries

BACKGROUND

Little of the previous literature has investigated associations between air pollution exposure and type 1 diabetes mellitus (T1DM)-related mortality, despite a well-established link between air pollution exposure and other autoimmune diseases.

METHODS

In a cohort of 53 million Medicare beneficiaries living across the conterminous United States, we used Cox proportional hazard models to assess the association of long-term PM_2.5 and NO₂ exposures on T1DM-related mortality from 2000 to 2008. Models included strata for age, sex, race, and ZIP code and controlled for neighborhood socioeconomic status (SES); we additionally investigated associations in two-pollutant models, and whether associations were modified by participant demographics.

RESULTS

A 10 μg/m³ increase in 12-month average PM_2.5 (HR: 1.183; 95% CI: 1.037-1.349) and a 10 ppb increase in NO₂ (HR: 1.248; 95% CI: 1.089-1.431) was associated with an increased risk of T1DM-related mortality in age-, sex-, race-, ZIP code-, and SES-adjusted models. Associations for both pollutants were consistently stronger among Black (PM_2.5: HR:1.877, 95% CI: 1.386-2.542; NO₂: HR: 1.586, 95% CI: 1.258-2.001) and female (PM_2.5: HR:1.297, 95% CI: 1.101-1.529; NO₂: HR: 1.390, 95% CI: 1.187-1.627) beneficiaries.

CONCLUSIONS

Long-term NO₂ and, to a lesser extent, PM_2.5 exposure is associated with statistically significant elevations in T1DM-related mortality risk.

Ambient NO2 exposure hinders long-term survival of Chinese middle-aged and older adults

INTRODUCTION

Serval longitudinal investigations have reported relationships between long-term nitrogen dioxide (NO₂) exposure and mortality. In developing countries such as China, however, the cohort evidence was extremely rare. In this study, we aimed to establish the concentration-response relationship between long-term exposure to NO₂ and mortality in Chinese adults.

METHODS

We conducted a prospective cohort study followed up from 2011 to 2018, by enrolling 15,440 participants aged ≥45 years from 28 provincial regions of China. NO₂ concentration estimates were derived from high-quality spatiotemporal datasets developed by machine learning methods and were assigned for each participant according to their residential cities. We applied Cox proportional hazard models with time-varying exposures to assess the association of all-cause death with long-term NO₂ exposure. Subgroup analyses were performed to identify effect modifications.

RESULTS

A total of 1646 death events occurred during 105,478.5 person-years' follow-up (median 7.1 years). No evident violation for linear NO₂-mortality relationship (P nonlinear = 0.332) was observed at a range of 7.4-45.0 μg/m³. Per 10-μg/m³ rise in NO₂ was associated with an hazard ratio of 1.220 (95% confidence interval: 1.103-1.350) for all-cause mortality. The association between NO₂ and mortality was generally robust after adjusting for co-pollutants including fine particulate matter or/and ozone. Only participants aged 65 and over (1.351 [1.193-1.531]) suffered from increased risks of death associated with NO₂ exposure, and an evident effect modification by age (P = 0.008) was identified. The elevated risk of death induced by NO₂ was also observed in participants living in rural areas and those with elementary school education or below, though effect modifications were non-significant in these subgroups.

CONCLUSIONS

This study provided novel evidence that long-term NO₂ exposure could be an independent risk for mortality among Chinese middle-aged and older adults. Our findings highlighted the importance of controlling air pollution induced by vehicle emissions.

Air quality trends in rural India: analysis of NO2 pollution using satellite measurements

India is a country with more than 67% of its population (947 million) residing in rural areas and 33% in urban areas (472 million) as of 2020. Therefore, health of the people living in rural India is very important for its future development plans, economy and growth. Here, we analyse the rural air quality using satellite measurements of NO₂ in India, as the sources of NO₂ are well connected to the industrial and economic uplift of a nation. Our analyses for the rural regions show distinct seasonal changes with the highest value (2.0 × 10¹⁵ molecules per cm²) in winter and the lowest in monsoon (1.5 × 10¹⁵ molecules per cm²) seasons. About 41% of the total NO₂ pollution in India is from its rural sources, but 59% of the urban sources were focused in the past studies. In addition, around 45% of the rural NO₂ pollution is due to road transport, whereas more than 90% of it in urban India comes from the power sector. Our assessment shows that the NO₂ exposure in rural regions is as serious as that in urban areas, indicating the need for more effective reduction of population exposure and protection of public health. Henceforth, this study reveals that rural India is gradually getting polluted from its nearby regions as well as from the new sources within. This is a big concern for the public health of the large rural population of India.