What Are the Net Benefits of Reducing the Ozone Standard to 65 ppb? An Alternative Analysis

The rationale behind updates to ambient ozone guidelines and standards

Although air quality has gradually improved in recent years, as shown by the decrease in PM2.5 concentration, the problem of rising ambient ozone has become increasingly serious. To reduce hazards to human health and environmental welfare exposure to ozone, scientists and government regulators have developed ozone guidelines and standards. These answer the questions of which levels of exposure are hazardous to human health and the environment, and how can ambient ozone exposure be guaranteed, respectively. So what are the basis for the ozone guidelines and standards? This paper reviews in detail the process of revising ozone guidelines and standards by the World Health Organization (WHO) and the United States Environmental Protection Agency (EPA). The present study attempts to explore and analyze the scientific basis and empirical methods for updating guidelines and standards, in a view to guide the future revision process and provide directions for further scientific research. We found many epidemiological and toxicological studies and exposure-response relationships provided strong support for developing and revising the ozone guidelines. When setting standards, ozone exposure has been effectively considered, and the economic costs, health, and indirect economic benefits of standard compliance were reasonably estimated. Accordingly, epidemiological and toxicological studies and the establishment of exposure-response relationships, as well as exposure and risk assessment and benefit-cost estimates of standards compliance should be strengthened for the further update of guidelines and standards. In addition, with the increasing prominence of combined air pollution led by ozone and PM2.5, more joint exposure scientific research related to ozone guidelines and standards should be undertaken.

Long-term air pollution exposure and diabetes risk in American older adults: A national secondary data-based cohort study

Type 2 diabetes is a major public health concern. Several studies have found an increased diabetes risk associated with long-term air pollution exposure. However, most current studies are limited in their generalizability, exposure assessment, or the ability to differentiate incidence and prevalence cases. We assessed the association between air pollution and first documented diabetes occurrence in a national U.S. cohort of older adults to estimate diabetes risk. We included all Medicare enrollees 65 years and older in the fee-for-service program, part A and part B, in the contiguous United States (2000-2016). Participants were followed annually until the first recorded diabetes diagnosis, end of enrollment, or death (264, 869, 458 person-years). We obtained annual estimates of fine particulate matter (PM2.5), nitrogen dioxide (NO2), and warm-months ozone (O3) exposures from highly spatiotemporally resolved prediction models. We assessed the simultaneous effects of the pollutants on diabetes risk using survival analyses. We repeated the models in cohorts restricted to ZIP codes with air pollution levels not exceeding the national ambient air quality standards (NAAQS) during the study period. We identified 10, 024, 879 diabetes cases of 41, 780, 637 people (3.8% of person-years). The hazard ratio (HR) for first diabetes occurrence was 1.074 (95% CI 1.058; 1.089) for 5 μg/m3 increase in PM2.5, 1.055 (95% CI 1.050; 1.060) for 5 ppb increase in NO2, and 0.999 (95% CI 0.993; 1.004) for 5 ppb increase in O3. Both for NO2 and PM2.5 there was evidence of non-linear exposure-response curves with stronger associations at lower levels (NO2 ≤ 36 ppb, PM2.5 ≤ 8.2 μg/m3). Furthermore, associations remained in the restricted low-level cohorts. The O3-diabetes exposure-response relationship differed greatly between models and require further investigation. In conclusion, exposures to PM2.5 and NO2 are associated with increased diabetes risk, even when restricting the exposure to levels below the NAAQS set by the U.S. EPA.

Long-term air pollution exposure and diabetes risk in American older adults: A national secondary data-based cohort study

Type 2 diabetes is a major public health concern. Several studies have found an increased diabetes risk associated with long-term air pollution exposure. However, most current studies are limited in their generalizability, exposure assessment, or the ability to differentiate incidence and prevalence cases. We assessed the association between air pollution and first documented diabetes occurrence in a national U.S. cohort of older adults to estimate diabetes risk. We included all Medicare enrollees 65 years and older in the fee-for-service program, part A and part B, in the contiguous United States (2000-2016). Participants were followed annually until the first recorded diabetes diagnosis, end of enrollment, or death (264, 869, 458 person-years). We obtained annual estimates of fine particulate matter (PM_2.5), nitrogen dioxide (NO₂), and warm-months ozone (O₃) exposures from highly spatiotemporally resolved prediction models. We assessed the simultaneous effects of the pollutants on diabetes risk using survival analyses. We repeated the models in cohorts restricted to ZIP codes with air pollution levels not exceeding the national ambient air quality standards (NAAQS) during the study period. We identified 10, 024, 879 diabetes cases of 41, 780, 637 people (3.8% of person-years). The hazard ratio (HR) for first diabetes occurrence was 1.074 (95% CI 1.058; 1.089) for 5 μg/m³ increase in PM_2.5, 1.055 (95% CI 1.050; 1.060) for 5 ppb increase in NO₂, and 0.999 (95% CI 0.993; 1.004) for 5 ppb increase in O₃. Both for NO₂ and PM_2.5 there was evidence of non-linear exposure-response curves with stronger associations at lower levels (NO₂ ≤ 36 ppb, PM_2.5 ≤ 8.2 μg/m³). Furthermore, associations remained in the restricted low-level cohorts. The O₃-diabetes exposure-response relationship differed greatly between models and require further investigation. In conclusion, exposures to PM_2.5 and NO₂ are associated with increased diabetes risk, even when restricting the exposure to levels below the NAAQS set by the U.S. EPA.

Assessment of volatile organic compound emissions from pesticides in China and their contribution to ozone formation potential

Solvents, components of pesticide emulsifiable concentrates (ECs), emit quantities of volatile organic compounds (VOCs) into the atmosphere. In the air, their active involvement in oxidative chemical reactions with oxidants exposed to ultraviolet solar radiation can result in the formation of ozone. The quantitative assessment of VOC emissions from agricultural pesticide applications remains hampered by many factors, especially the volatility coefficient of solvents in pesticides. Therefore, this study identified solvents in 20 widely used pesticide products in China. The volatility coefficients of the solvents were investigated based on a spraying test to evaluate VOC emissions from agricultural pesticide applications and their ozone formation potential (OFP). The results suggest that VOC emissions from agricultural pesticide applications amount to 0.60 Mt in 2017, with insecticides, fungicides, and herbicides contributing 0.39 Mt, 0.12 Mt, and 0.09 Mt of VOCs, respectively. Since VOC emission and maximum incremental reactivity (MIR) led to an OFP value (2.1 g ozone/g product) for insecticides, a primary consideration should be to decrease use of solvents with high volatility coefficients and large MIR values in insecticide products. This work could provide valuable insights regarding response options to reduce VOC emissions and ozone formation.

Ozone exposure upregulates the expression of host susceptibility protein TMPRSS2 to SARS-CoV-2

SARS-CoV-2, a novel coronavirus and an etiologic agent for the current global health emergency, causes acute infection of the respiratory tract leading to severe disease and significant mortality. Ever since the start of SARS-CoV-2, also known as the COVID-19 pandemic, countless uncertainties have been revolving around the pathogenesis and epidemiology of the SARS-CoV-2 infection. While air pollution has been shown to be strongly correlated to increased SARS-CoV-2 morbidity and mortality, whether environmental pollutants such as ground-level ozone affects the susceptibility of individuals to SARS-CoV-2 is not yet established. To investigate the impact of ozone inhalation on the expression levels of signatures associated with host susceptibility to SARS-CoV-2, we analyzed lung tissues collected from mice that were sub-chronically exposed to air or 0.8 ppm ozone for three weeks (4 h/night, 5 nights/week), and analyzed the expression of signatures associated with host susceptibility to SARS-CoV-2. SARS-CoV-2 entry into the host cells is dependent on the binding of the virus to the host cellular receptor, angiotensin-converting enzyme (ACE2), and its subsequent proteolytic priming by the host-derived protease, transmembrane protease serine 2 (TMPRSS2). The Ace2 transcripts were significantly elevated in the parenchyma, but not in the extrapulmonary airways and alveolar macrophages, from ozone-exposed mice. The TMPRSS2 protein and Tmprss2 transcripts were significantly elevated in the extrapulmonary airways, parenchyma, and alveolar macrophages from ozone-exposed mice. A significant proportion of additional known SARS-CoV-2 host susceptibility genes were upregulated in alveolar macrophages and parenchyma from ozone-exposed mice. Our data indicate that the unhealthy levels of ozone in the environment may predispose individuals to severe SARS-CoV-2 infection. Given the severity of this pandemic and the challenges associated with direct testing of host-environment interactions in clinical settings, we believe that this ozone exposure-based study informs the scientific community of the potentially detrimental effects of the ambient ozone levels in determining the host susceptibility to SARS-CoV-2.

Ozone exposure upregulates the expression of host susceptibility protein TMPRSS2 to SARS-CoV-2

Background

SARS-CoV-2, a novel coronavirus, and the etiologic agent for the current global health emergency, causes acute infection of the respiratory tract leading to severe disease and significant mortality. Ever since the start of SARS-CoV-2, also known as COVID-19 pandemic, countless uncertainties have been revolving around the pathogenesis and epidemiology of the SARS-CoV-2 infection. While air pollution has been shown to be strongly correlated to increased SARS-CoV-2 morbidity and mortality, whether environmental pollutants such as ground level ozone affects the susceptibility of individuals to SARS-CoV-2 is not yet established.

Objective

To investigate the impact of ozone inhalation on the expression levels of signatures associated with host susceptibility to SARS-CoV-2.

Methods

We analyzed lung tissues collected from mice that were sub-chronically exposed to air or 0.8ppm ozone for three weeks (4h/night, 5 nights/week), and analyzed the expression of signatures associated with host susceptibility to SARS-CoV-2.

Results

SARS-CoV-2 entry into the host cells requires proteolytic priming by the host-derived protease, transmembrane protease serine 2 (TMPRSS2). The TMPRSS2 protein and Tmprss2 transcripts were significantly elevated in the extrapulmonary airways, parenchyma, and alveolar macrophages from ozone-exposed mice. A significant proportion of additional known SARS-CoV-2 host susceptibility genes were upregulated in alveolar macrophages and parenchyma from ozone-exposed mice.

Conclusions

Our data indicate that the unhealthy levels of ozone in the environment may predispose individuals to severe SARS-CoV-2 infection. Given the severity of this pandemic, and the challenges associated with direct testing of host-environment interactions in clinical settings, we believe that this mice-ozone-exposure based study informs the scientific community of the potentially detrimental effects of the ambient ozone levels determining the host susceptibility to SARS-CoV-2.

Ozone therapy in veterinary medicine: A review

Ozone (O₃) is a triatomic form of oxygen. As O₃ rapidly dissociates into water and releases a reactive form of oxygen that may oxidize cells, the gas mixture of O₃/O₂ is used in medicine. ATP is widely available for cellular activity. O₃ can be administered via the systemic and local routes. Although O₃ is known as one of the most powerful oxidants, it also promotes antioxidant enzymes. Additionally, it stimulates some of the cells of the immune system and inactivates pathogens, including bacteria, fungi, yeasts, protozoa, and viruses. Owing to these activities, O₃ is used to improve several diseases, both in human and in veterinary medicine. Considering the wide scope of O₃ application, the aim of this review was to reiterate the mechanisms of action of O₃ and its utilization in different mammalian species (bovine, ovine-caprine, equine, canine, porcine).

Skin damage by tropospheric ozone

Tropospheric (ground level) ozone (O3) is a secondary pollutant, emerging from other pollutants in the sunshine. Exposure to O3 correlates with higher pulmonary and cardiovascular mortality and affects reproductive health and the central nervous system acutely and chronically. Skin might be a potentially overlooked target organ of ambient O3. The experimental evidence suggests a positive correlation of O3 exposure with oxidative damage, impaired antioxidant defence and proinflammatory response in the skin. In time series studies it was observed that acute rises in O3 levels correlated with seeking medical help for skin conditions; however, whether these findings are specific to O3, is not yet clear. There is preliminary epidemiological evidence that long-term exposure to O3 is associated with premature skin aging. This finding was independent of co-exposure to other environmental factors affecting skin (e.g. ultraviolet radiation and air pollution). As concentrations of O3 are rising in many regions of the world, adverse cutaneous effects of O3 present a relevant public health concern.