Air Pollution's Link To Anemia: What You Need To Know

Air pollution is a potential contributing factor to the high prevalence of anemia in the elderly. Anemia is a highly prevalent disorder in elderly populations, with between 2.9% and 60.1% of older adults affected. Approximately two-thirds of anemia in American elderly is caused by chronic inflammation or is unexplained.

A few studies have investigated the link between air pollution and anemia. A study of 4,121 older Americans found that an increase in exposure to fine particulate matter (PM2.5) and nitrogen dioxide (NO2) was associated with a higher prevalence of anemia and lower hemoglobin levels. Another study of 10,611 older Chinese adults found that exposure to PM and NO2 was associated with increased anemia prevalence and decreased hemoglobin levels.

In addition, a study of 40 housewives in South Korea found that the use of indoor air purifiers decreased PM levels and improved anemia indicators. Similarly, a study of 3,163 pregnant women in Guatemala, India, Peru, and Rwanda found that exposure to carbon monoxide (CO) was associated with higher hemoglobin levels and lower anemia prevalence.

These findings suggest that air pollution may be a risk factor for anemia in older adults.

Air pollution and anemia as risk factors for pneumonia in children

Pneumonia is a leading cause of death in children under five, and various environmental and host factors contribute to its pathogenesis. Among these factors, ambient air pollution and malnutrition, particularly anemia, have been identified as major risk factors. This review will discuss the relationship between air pollution, anemia, and pneumonia in children, focusing on the synergistic effects of these risk factors and the underlying physiological mechanisms.

Air Pollution and Anemia as Risk Factors

A retrospective cohort analysis conducted in 2011 assessed the risk factors for pneumonia in Ecuadorian children. The study found that ambient air pollution and anemia were independently associated with an increased risk of pneumonia hospitalization and acute respiratory infections. Children exposed to higher levels of air pollution had more pneumonia hospitalizations and total respiratory illnesses. Additionally, higher pollution exposure was significantly associated with pneumonia hospitalization in anemic children, while no difference was detected in non-anemic children. These findings suggest a possible interaction between air pollution and anemia as risk factors for pneumonia.

Physiological Mechanisms

The central pathophysiological deficit in pneumonia is poor tissue oxygenation. Both anemia and air pollution can contribute to decreased oxygen delivery to tissues. Anemic children have a reduced oxygen-carrying capacity, and air pollution can lead to dyshemoglobinemia, which decreases oxygen saturation in the blood. Vehicular engine combustion, a major source of air pollution, produces carbon monoxide and nitrogen oxides that bind to hemoglobin, reducing oxygen saturation. Additionally, air pollution can increase systemic inflammation, which can affect bone marrow stimulation and erythropoiesis, leading to decreased red blood cell production and anemia over time.

Preventive Measures

The findings of the retrospective cohort analysis have important implications for preventing pneumonia in children. By addressing both nutrition-related anemia and reducing air pollution levels, it may be possible to reduce the incidence of pneumonia and associated hospitalizations. Improving nutrition can help reduce the prevalence of anemia, while implementing measures to decrease ambient air pollution, such as reducing vehicular traffic and combustion emissions, can lower children's exposure to harmful pollutants.

Air pollution and anemia are significant risk factors for pneumonia in children, and their synergistic effects can increase the likelihood of pneumonia hospitalization. The underlying physiological mechanisms involve decreased oxygen delivery to tissues due to reduced oxygen-carrying capacity and dyshemoglobinemia. Preventive measures targeting both nutrition and air pollution reduction may help reduce the burden of pneumonia in children.

Anemia indicators can be improved by fine dust reduction management

Anemia is a highly prevalent disorder in elderly populations, with approximately two-thirds of anemia in American elderly caused by chronic inflammation or remaining unexplained. A potential contributing factor may include air pollution exposures, which have been shown to increase systemic inflammation and affect erythropoiesis.40 housewives in Seoul and Ulsan, Republic of Korea, found that the use of indoor air purifiers decreased PM and impacted anemia indicators. The study found that an increase in indoor PM2.5 levels was associated with a decrease in MCHC and hemoglobin. The decrease in indoor PM2.5 concentration by air purifier was associated with an increase in MCHC and hemoglobin. In particular, after air purifier intervention, the amounts of MCHC and hemoglobin significantly increased.

Another study of 10,611 older Chinese adults found that all the studied pollutants (PM10, PM2.5, PM1, and NO2) were significantly associated with increased anemia prevalence in a single-pollutant model. These air pollutants were also associated with lower concentrations of hemoglobin.

In a study of 809 children in Quito, Ecuador, children exposed to higher levels of air pollution had more pneumonia hospitalizations and total respiratory illness, stunting, and anemia compared to children exposed to lower levels of air pollution. Children exposed to higher levels of air pollution also had significantly lower oxygen saturation, consistent with air pollution-related dyshemoglobinemia.

A study of 139,368 children aged 6–59 months in Lima, Peru, found that anemic children compared with nonanemic children are mainly male, have low body weight, higher rate of stunting, and live in an environment with high PM2.5 concentration. A slight decrease in hemoglobin and an increase in the probability of moderate/severe anemia were observed with increased exposure to PM2.5.

In conclusion, anemia indicators can be improved by fine dust reduction management.

Associations between air pollution and anemia in older Chinese adults

Anemia is a highly prevalent disorder in elderly populations, with between 2.9% and 60.1% of older adults affected, depending on the population studied. Older adults with anemia are at higher risk of severe adverse health outcomes, including mortality, impaired functional status, impaired cognitive function, and cognitive disorders such as Alzheimer's disease. While the causes of anemia in older adults include micronutrient deficiencies, renal insufficiency, and anemia of chronic inflammation, up to one-third of anemia in American elderly is unexplained.

Air pollution has been shown to increase systemic inflammation and affect erythropoiesis, and thus, it has been hypothesized to be a contributing factor to anemia. However, few studies have investigated the associations between air pollution and anemia.

This study aims to examine the associations between long-term exposure to ambient particulate matter (PM) and nitrogen dioxide (NO2) with anemia prevalence and hemoglobin levels in older Chinese adults.

Methods

The study used data from the World Health Organization (WHO) Study on global AGEing and adult health (SAGE) China, a longitudinal study of adult respondents from China during the 2007-2010 period. The study population consisted of 10,611 older Chinese adults aged 50 years or older with valid hemoglobin measurements.

The average community exposure to ambient air pollutants (PM10, PM2.5, PM1, and NO2) for each participant was estimated using a satellite-based spatial statistical model. Hemoglobin levels were measured from dried blood spots.

Linear regression models and modified Poisson regression with robust error variance were used to examine the associations between air pollutants and anemia prevalence and hemoglobin levels. The models were adjusted for potential confounders, including age, sex, body mass index (BMI), tobacco use, physical activity, education level, fruit and vegetable intake, alcohol use, type of fuel used at home, and median household income.

Results

All the studied pollutants were significantly associated with increased anemia prevalence in single-pollutant models. An interquartile range (IQR) increase in the three-year moving average of PM10, PM2.5, PM1, and NO2 was associated with a 5%, 11%, 13%, and 42% increase in anemia prevalence, respectively.

These air pollutants were also associated with lower hemoglobin concentrations. An IQR increase in PM10, PM2.5, PM1, and NO2 was associated with a decrease in hemoglobin levels of 0.53, 0.52, 0.55, and 1.71 g/dL, respectively.

The study findings suggest that air pollution exposure was significantly associated with increased prevalence of anemia and decreased hemoglobin levels in a cohort of older Chinese adults. These results indicate that air pollution may be an important risk factor for anemia in older adults.

The effect of air purifiers on anemia indicators

Anemia is a highly prevalent disorder in elderly populations, associated with numerous adverse health outcomes, including increased mortality, impaired functional status, and cognitive disorders. Approximately two-thirds of anemia in American elderly is caused by chronic inflammation or is unexplained. A potential contributing factor may include air pollution exposures, which have been shown to increase systemic inflammation and affect erythropoiesis.

Methods

This study investigated the decrease in indoor PM concentration by air purifiers on indicators of anemia, such as hemoglobin, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC). We analyzed the data of 40 housewives who were subjected to an air purifier intervention in Seoul and Ulsan, Republic of Korea. Indoor exposure levels of PM2.5 and PM10 were analyzed with sensor-adjusted and gravimetric measurement. We also investigated the same anemia indicators before and after the installation of an air purifier for three months (short-term: one month, long-term: three months). Statistical analysis was performed by a multiple linear model and a linear mixed model.

Results

The indoor PM exposure levels and air purifier use were related to anemia indicators (hemoglobin and MCHC). The increase in indoor PM2.5 level was associated with a decrease in MCHC (β: 0.034, P = 0.031) and hemoglobin (β: 0.013, P = 0.04). The decrease in indoor PM2.5 concentration by air purifier was associated with an increase in MCHC (β: 0.204, P = 0.087) and hemoglobin (β: 0.190, P = 0.039). In particular, after air purifier intervention, the amounts of MCHC and hemoglobin significantly increased.

Our results suggest that indoor air purifier use could decrease indoor PM level and the risk of anemia in housewives. Because the effect on anemia is subacute, it was confirmed three months after air purifier operation. In conclusion, anemia indicators can be improved by PM reduction management.

The effect of outdoor air pollution on hemoglobin levels and anemia in children

Air pollution has been linked to a range of adverse health outcomes, including an increased risk of mortality, impaired cognitive function, and cardiovascular disease. Recent studies have also suggested a potential association between air pollution and anemia, a blood disorder characterized by low hemoglobin levels or red blood cell counts. However, the majority of research on this topic has focused on specific vulnerable groups, such as the elderly, children, and pregnant women. The following paragraphs will explore the available evidence on the effects of outdoor air pollution on hemoglobin levels and anemia in children.

Evidence from epidemiological studies

Several epidemiological studies have investigated the relationship between air pollution and anemia in children. A study by Mehta et al. (2021) examined the association between ambient PM2.5 exposure and anemia outcomes in children under five years of age in India. They found a significant association between PM2.5 exposure and anemia, suggesting that air pollution may contribute to the development of anemia in this vulnerable age group. Similarly, Morales-Ancajima et al. (2019) found a positive association between increased outdoor PM2.5 concentrations and the prevalence of moderate to severe anemia in children aged 6-59 months in Lima, Peru. These findings provide evidence that air pollution may be a risk factor for anemia in children.

Biological mechanisms

While the exact mechanisms underlying the relationship between air pollution and anemia are not yet fully understood, several biological pathways have been proposed. Air pollutants are known to induce a chronic inflammatory response in the body, which can lead to changes in hemoglobin levels and an increased risk of anemia. Additionally, air pollution exposure can increase the secretion of reactive oxygen species, leading to oxidative stress and iron deficiency. Inflammatory cytokines caused by air pollution can also lead to a deficiency in erythropoietin secretion, resulting in a decrease in red blood cell production and hemoglobin levels. These biological mechanisms provide a plausible explanation for the observed associations between air pollution and anemia in children.

Interventions to reduce air pollution exposure

Given the potential health risks associated with air pollution exposure, interventions to reduce exposure are important. The use of air purifiers, for example, has been shown to decrease indoor PM levels and improve anemia indicators in housewives, who are particularly vulnerable to indoor air pollution due to their daily household chores. This suggests that air purifiers may be an effective strategy to mitigate the health impacts of air pollution, including the risk of anemia.

In conclusion, the available evidence suggests that outdoor air pollution may have a detrimental effect on hemoglobin levels and anemia in children. However, more research is needed to fully understand the underlying mechanisms and the long-term health impacts of air pollution exposure in this vulnerable population. Interventions to reduce air pollution exposure, such as the use of air purifiers, may be beneficial in mitigating these health risks.

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