Air Pollution,  Health,  Science,  Toxic Exposure,  Urbanization

The unborn baby: Healthy pregnant mothers exposed to air pollution from road traffic inhale toxic particles that may end up in the placenta

By Roberta Attanasio

According to a recently published study, carbon and metal particles from road traffic, once inhaled, reach one of the many places where we would rather not find them—the unborn baby’s life support system, best known as placenta.

Lead author Jonathan Grigg said: “Our study for the first time shows that inhaled carbon particulate matter in air pollution, travels in the blood stream, and is taken up by important cells in the placenta.” For the study, researchers analyzed placentas from 15 healthy non-smoking women, donated after the birth of their children. All women delivered healthy babies. However, they lived in an environment that exposed them to high levels of particulate matter originating from urban traffic. Indeed, the particles observed in the placental cells closely resemble—in size, shape and composition—those emitted by traffic-related sources or formed from them.  

Particulate matter (also called particle pollution) is a mixture of solid particles and liquid droplets found in the air, which come in many sizes and shapes and are made up of hundreds of different chemicals. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope. Some particles are emitted by construction sites, unpaved roads, fields, smokestacks or fires, but most form in the atmosphere as a result of complex reactions of chemicals such as sulfur dioxide and nitrogen oxides, which are pollutants emitted from power plants, industries and automobiles.

The researchers found—within the placental cells—not only carbon particles, but also particles containing carbon with a mixture of chemicals found in vehicle exhaust, such as iron, phosphorus, calcium, silica, aluminum, titanium, chromium, and cerium, which arise from fuel and oil additives. How did these particles get into the placental cells? Particles present in air pollution are inhaled, and then from the lungs translocate to distant organs through the blood stream. Macrophages and trophoblasts— the primary resident phagocytes in the placenta—pick them up. Phagocytes are cells of the innate immune system also known as the “big eaters”—they engulf the particles with the aim of “cleaning up” the placenta.

Lisa Miyashita, a study co-author, said: “We have thought for a while that maternal inhalation could potentially result in pollution particles traveling to the placenta once inhaled. However, there are many defense mechanisms in the lung that prevent foreign particles from traveling elsewhere, so it was surprising to identify these particles in the placental cells from all 15 of our participants.”

Why is it worrisome to find particulate matter in placental cells? “The placenta is a distinctive and defining anatomical characteristic of mammals. Composed primarily of fetal tissue, it is the conduit through which maternally produced nutrients and oxygen enter the fetus, and metabolic waste products return to the mother for excretion. It also enables a developing baby to guide pregnancy, from assisting in embryo implantation to helping maintain the gravid state and instructing the mother’s body about what is needed for its well-being. Placental signaling can even calibrate the rate of fetal growth and influence the length of the pregnancy.”

Particulate matter could adversely affect the unborn baby, especially heart and brain, although more research is needed to confirm these concerns. Fiona Miller Smith, Chief Executive of Barts Charity in the UK, the organization that funded the study, said: “This is an incredibly important study and immensely relevant to mums-to-be in our local community, indeed in any urban community anywhere in the world.”

Photo by John Arano on Unsplash

These results are, unfortunately, not surprising, as another study showed last year that black carbon particles—a component of particulate matter derived from combustion—accumulate on the fetal side of the placenta. The study, which included 25 placentas from non-smoking women, also showed that the number of particles on the fetal side of the placenta correlated with the air pollution levels experienced by the mothers. The placentas of mothers who lived near main roads contained and average of 20,000 particles per cubic millimeter, whereas those from mothers who lived further away contained an average of 10,000 particles per cubic millimeter. Tim Nawrot, lead study author, told The Guardian: “This is the most vulnerable period of life. All the organ systems are in development. For the protection of future generations, we have to reduce exposure.” He said that while governments had the responsibility of cutting air pollution, people should avoid busy roads when possible.

Copyright © 2016-2020 The Global Fool


  • Marc Macchiaverna

    This is a topic I’ve often thought about considering that transit exhaust pollution affects postnatal children as well as adults. We cannot remove this sort of particulate soon enough. However, there are still more forms of pollution originating from vehicular transport that an electric vehicle would still emit. Non-Exhaust Emissions or NEE are particles from brake pads, tires, and road wear. Many of these particles are heavy and often settle on the road surface after spending time in the air. However, once a car uses a section of the road, these particles are re-aerosolized from the surface. This scenario plays out every time a car, electric or not, drives by. The amount of particulate is far higher, and dissimilar to exhaust particulate that was so well spelled out in the article above. We know much less about the effects of these NEE’s on pregnant mothers and children in utero, let alone the general walking public exposed to these agents every day in urban and suburban areas.
    One study suggests that this road dust is non-carcinogenic but does have significant pro-inflammatory properties. This is extremely important considering that we may not see the effects of humans in utero yet, but we know through mountains of evidence that cardiovascular events are the #1 cause of death on the planet. While we are still stuck on the chicken or the egg theory as to which comes first, inflammation or cholesterol adhesion onto endothelium causing inflation causing the eventual plaque formation, we do know that inflammation in general does significantly exacerbate morbidity.
    Aside from the immediate inhalation of NEE pollution, there is its entry into the ecological system at large. It is important to note that this pollution does significantly wash away with very heavy and prolonged boughts of rain. However, where does the bulk of this material end up? And without rain, as in more arid regions, these NEE linger and build-up on road surfaces and can be inhaled in significant quantities, as in the South Western US.
    Lastly, we’re at a century of automobile use in the world. While we have been regulating exhaust for decades now, NEE’s are out of sight and out of mind for regulators and all but a few scientists and concerned citizens who are just now looking into the issue.

  • liepav

    After reading this article, I had a few questions running through my mind and I hope someone can provide some insight to my thinking. As stated, the particles get into the body when they are inhaled by the mother, and then from the mother’s respiratory system those droplets translocate to different organs through the bloodstream. When they arrive at the placenta, macrophages and trophoblasts act as phagocytes and pick up those particles and engulf them. Interestingly, macrophages regulate trophoblast functions as the placenta remodels during the course of pregnancy. Studies show that a balance between anti- and pro-inflammatory environments that regulate the cellular interactions between the fetus and mother, and disturbances in this balance contribute to poor remodeling and disorders as a result. Could limited exposure to pollutants, such as one day spent in the city perhaps, offer some benefit in maintaining this balance?

    The placenta connects the mother to the baby and allows for nutrient and oxygen passage to the developing fetus, which answers why the placenta picks up particles that travel through the lungs in the first place. However, if the mother’s lungs immune cells understand these particles are foreign and toxic, why doesn’t the mother’s immune system elicit a response to eradicate them? In all 15 participants, the particle cells traveled past the lungs into the placenta despite all the defense mechanisms the lungs possess. Do you believe that the mother’s lungs do not have as many immune cells as the gut epithelia (for example), because by creating a reactive respiratory system, consecutive inflammatory response from poor air quality could insist which would hurt the host, aka the mother, more than provide protection? Is it possible that the lungs purposely pass such particles into the bloodstream to travel to other organs which have the potential to rid of those particles in a better fashion? I understand these thoughts might be extraneous, but I would love to hear any thoughts from an immunological and developmental perspective.

    Overall, this article provides valuable insight but dangles the overarching questions: should we be worried for mothers who cannot escape an urban lifestyle? Are there any long-term adverse health effects that harm the development of the fetus from the accumulation of the particulate matter? Moreover, does the placenta prevent or deter these long-term adverse health effects from occurring?

    Perhaps after reading this, some mothers who are fortunate enough can consider a portion of their pregnancy away from high traffic roads and congested cities. If they can, is there a certain time frame/trimester they should spend away from an urban setting? If they cannot, is there something a hopeful mother can do to make up or prevent any possible adverse health effects that may hurt the development of the fetus?

    After speculating, I decided to dive into some related research:

    Newer evidence dated in 2017 from Isfahan, Iran has shown that particulate matter has an effect on the birth weight and placental weight of newborns. Limited studies focus on the interplay between air pollution and birth and placental weight, but it known that there an inverse relationship between them. Low birth weight is a key indicator of maternal health; neonates with a low birth weight have a much greater chance of having long term neurological disabilities, language impairment and increased risks of carrying chronic diseases. Studies also showed that it does not matter at what stage of pregnancy the mother is exposed to air pollutants, as a reduction of birth weight and placental weight was seen across many mothers at various times during their pregnancy, even when the exposure time was limited to as short as one week. However, other studies claimed that it is not only high trafficked roads which lead to the most damaging effects, but the quality of the air of the surrounding city as well, along with other factors like a mother’s oxidative stress, inflammation and/or endocrine disruption that harm the placenta, which are known to be higher in urban areas away where there is a dearth of greenery.

    Endocrine research from 2019 suggests that a pregnant woman’s diet may have along with environmental threats could have an effect on the health of a developing fetus. Fungi produce xenoestrogens, chemical compounds commonly found in grain-based foods we commonly eat. A type of xenoestrogen called zearalenone is characterized by its mycotoxin has a large impact on the body’s hormonal balance and can get through the placental barrier easily. Women with unbalanced diets are known to expose their fetuses to higher levels of zearalenone. Although the exact mechanisms are not known, this toxin is capable of inducing maternal growth restrictions and hormone dysfunction and causes structural abnormalities in the uterus and ovaries of the adult offspring.

    Therefore, teratogens predispose a fetus’ development, which are dependent on advantageous or detrimental socioeconomic factors. Pregnant women should be made wary of this knowledge and if they cannot prevent living in urban settings, it is vital that they maintain a nutrient-rich diet along with pre-natal supplementation in efforts to best battle against environmental toxins.

  • Sharon Lackwood

    This article discusses the negative impacts that air pollution can have on the placenta and in turn the fetus growing inside of it. The article explains that within a study that they conducted using the placenta of 15 healthy non-smoking mothers, they found that placental cells not only contained carbon particles, but carbon particle mixed with other chemicals that arise from vehicle exhaustion and other pollutants. The placenta acts as the fetus’s life support during development, providing oxygen and nutrient-rich blood as well as immune cells to the fetus through blood vessels. Therefore, the particulate matter is concerning because there is evidence that it can affect the developing baby’s heart and brain. Therefore, my question is would the overactivation of the macrophages and trophoblasts within the placenta cause the underdevelopment of the baby’s microbiome, therefore causing an overactive immune system and obesity?

    I believe that the answer is yes. I believe that because there is an overactivation of the fetus’s immune system due to the presence of foreign particles within the placenta, the immune cells would begin to attack the foreign particles with a reaction that we know as hypersensitivity type 1. There have been studies that have shown that pregnant mothers who live in urban overpopulated areas are at a far greater risk of their baby developing asthma at some point in their childhood. I believe that with the over activation of the immune system, there would be a competition for space within the fetus that would push out essential bacteria that would make up their microbiome and as a result they could have a dysbiosis that could result in obesity when they get older or even cause underdevelopment of their organs within utero. Overall, air pollution in overpopulated urban areas can be very dangerous to everyone and pregnant mothers need to be warned of the affects that could impact their babies.

    References used:

    • Fikir Wordofa

      You ask a very interesting question regarding fetal overactivation of macrophages/trophoblasts and consequently an underdeveloped microbiome and overactive immune system. This made me think about allergies and question if that could be a potential consequence to fetal macrophage activation due to pollution. There is another article in the global fool webpage that discusses this link further, titled “Allergies in Young Children: Effects of Exposure to Multiple Air Pollutants During Prenatal and Early Life”. In the article it addresses a new finding that “Prenatal and early-life exposure to indoor air-polluting factors and allergic sensitization at 2 years of age” []. The article used data from 108 mothers’ and their children that were followed for 2 years for the study and preformed periodic skin prick checks to test for allergies. This test really focused on indoor pollutants that can have a lot of additives and non-natural byproducts (e.g., air fresheners) that can make the fetus/child more susceptive to allergies. Consequently, I tried to find research on outdoor pollutants and allergies and I found a study published in 2020 that highlights: “Early-life exposure to outdoor air pollution and indoor environmental factors plays an important role in the development of childhood allergic diseases, and the synergy between indoor and outdoor exposures increases allergy risk.” This makes sense from an immunological standpoint because if macrophage and IgE antibodies are being elected prenatally to pollutants/exposures that are not necessarily pathogenic, a child is likely to be born with a hypersensitivity to non-lethal factors. As allergies continue to climb in developed countries understanding the immune system role especially in the prenatal environment will aid greatly to understanding the etiology of allergies.

      Chan Lu, Dan Norbäck, Yuguo Li & Qihong Deng (2020) Early-life exposure to air pollution and childhood allergic diseases: an update on the link and its implications, Expert Review of Clinical Immunology, 16:8, 813-827, DOI: 10.1080/1744666X.2020.1804868

    • liepav

      Hey Sharon,

      I enjoy how you analyzed the potential hypersensitivity effect caused by pollutants in urban/highly road trafficked areas. It was truly an interesting and beneficial read.

      Your reasoning for how increasing particulate matter invaginating as foreign substances in placental cells over time causes the fetus to have an overactivation of macrophages and trophoblasts and therefore elicit the child to have hypersensitivity type 1 reactions seems to be correct.

      At first glance, I thought that there was no way the second part of your question was correct in how the overactive immune system contributes to the predisposition of obesity, but I was surprised to find you were correct again. From my understanding, you questioned whether a neonate’s gut microbiome is limited because of the overactive response of the immune cells in the placental microbiome so the gut microbiome of the developing child lacks critical bacteria and/or enzymes to break down food which contributes to excess fat storage and therefore results in obesity. After following up, it seems that particles cross into the intestinal epithelia through M cells on Peyer’s patches and through enterocytes. M cells are cells of the mucosal lymphoid tissue that transport antigens from the lumen to cells of the immune system, which can initiate an immune response to begin. Increased concentrations of this particulate matter altered how immune cells responded to this constant infiltration as well as bacterial colonization and survival. Although it is known that macrophages are multi-faceted in the immune response, it is unclear whether it is the macrophages, trophoblasts or other immune cells that alter bacterial colonization. Particulate matter decreased the amount of Bacteriodaceae and Corynebacteriaceae in the gut microbiome, in which low levels are correlative with obesity.

      This finding makes me wonder: by knowing that pollution contributes to low levels of the named bacteria which are correlative with obesity, then could there ways we could supplement the fetus with the designated bacteria that are known to drop to low levels at the appropriate time to prevent predispositions to obesity?

      Although the exact interplay between gut microbiota and respiratory diseases are poorly understood, new studies from 2020 show that chronic exposure to particular matter not only effects pregnant women and fetuses, but effects the respiratory tract and gut microbiome of others as well. Following exposure to particulate matter from living in highly polluted urban dwelling areas, an increase in Firmacutes is seen. Increases in Firmacutes causes imbalances in the gut microbiota which dysregulates other bacteria and causes the release of the bacterial byproduct LPS to cause an inflammatory response. The inflammatory response is said to be correlative with the pathogenesis of chronic obstructive pulmonary disease, but what responses are causes or consequences to cause debilitating diseases are still unclear in this mechanism.

      Either way, thank you for sharing your insightful information. It looks like everyone could benefit from taking a break from the city for a while and/or making sure to keep a nutrient-rich and balanced diet and lifestyle.

  • Marilyn M

    Hello Ali,

    I agree that exposure to pollution will lead to differences in the trophoblasts based on the papers you shared. I also agree with the idea that the uptake of these particles can damage the tissue. There is evidence however that suggests that the effects of this exposure largely depend on sex. Bolton et al 2017 found that air pollution had an effect on microglia-neuron interaction in the fetus with male mice showing a different pattern in this as well as with their TLR4 development when exposed to air pollution. TLR4 obviously being crucial in activating a cytokine storm to bring innate immune cells to the site of tissue damage or infection.

  • Marilyn M

    This post is interesting to me because it lines up with what we know about how urban living affects the physiology of nonpregnant humans. For example, one study ( shows how urban living is tied to cardiovascular disease due to changes in lifestyles that human evolution has not quite caught up with. This study is further expanding on that idea by showing how urban lifestyles affect us even before we are born.

    This study was also interesting because it demonstrated that the phagocytes in the placenta did in fact uptake the diesel fuel particles. I would assume that this likely means that the adult mucosal immunity in the respiratory tract does something similar since it also contains macrophages and phagocytes. In their discussion, the authors cite another study that found something similar. In Bove et al 2019, the authors found that black carbon particles were shown to pass through the placenta to the fetus ( I would expect the mucosal immune system of the fetus to contain macrophages and/or phagocytic cells that perform a similar function as seen in adults since there are likely other nanoscopic particles passing through the placenta that the fetal immune system must deal with. One study, Bolton et al 2014 demonstrated that inflammatory responses in fetuses exposed to air pollution were different than ones that were not. ( This further supports the hypothesis that fetuses must have a response of some sort to this kind of exposure similar to our own where macrophages ingest particles and destroy them while informing the adaptive immune system so that we can mount more specific immune responses if we are exposed again.

    Reducing pollution and increasing green spaces will benefit future generations by preventing carbon particle exposure.

    • Sharon Lackwood

      Hi Marylin,

      Thank you so much for the insightful read about cardiovascular health and pollution. It’s actually refreshing to see that cardiovascular health can have other causes as opposed to the obvious obesity. I believe that our society focuses heavily on obesity and attributes all metabolic syndrome diseases to it- I know that it can cause them I’m not saying that it won’t- however, doctors look at someone who is obese and automatically thinks that they suffer from metabolic syndrome diseases rather than looking and seeing a healthy individual simply having a gut microbiome dysbiosis. It was a great read and gave some insight into the “correct lifestyle”. Maybe researchers who see that effects of the toxic foreign bodies could come up with a plan for expecting mothers to combat the complications that could arise from the inhaling of toxic chemicals. Maybe doctors could formulate a plan that expecting mothers who live in over populated urban environments should be on a drug- although uncomfortable- that causes heavy mucus production so that there could be minimal risk on the foreign bodies penetrating the placenta and affecting the baby.

  • Andrew Ho

    Being previously naive to the topic of toxic particles affecting placental tissue, following up on this post and the intersection of urban pollution and immunology has been particularly enlightening. A primary question of mine is how the mother’s immune system could react to foreign substances that enter the bloodstream, from pollution particularly. It is well known that maternal health critically affects the health of the fetus and human development. Many classical sources of external chemicals include alcohol consumption, drug and tobacco use, diet, prenatal drugs, and environmental. A mother who is a resident or employee in a metropolitan or urban environment however is chronically forced to be subjected to what is deemed urban pollution: the presence of potentially poisonous and harmful substances sourced from human-derived emissions. As mentioned in the blog post, it has been demonstrated that toxic carbon and metal-bearing nanoparticles inhaled by mothers were found in placental tissue phagocytes. Air pollution in urban areas, sourced from motor traffic, fuel burning, and other emissions, have been linked to low birth rates in a study in the UK. Post-partum long-term developmental and health burdens on fetuses have yet to be scrutinized and characterized in urban versus rural populations have yet to be performed. It is suggested however that the fetus can be negatively affected by these exogenously introduced nanoparticles and can have serious health burdens.

    A study in Seville, Spain by Cerrillos et. al. in 2019 demonstrated that fetuses exposed to toxic elements that cross the placenta compromises the protective functions of the organ. Prenatal exposure is additionally linked with cognitive, motor, and intellectual development. The study involved collection of 62 placental samples post-partum in order to determine individual mineral element effects on newborn parameters, pregnancy details, and epidemiologic information (survey based). It was concluded that pregnant women exposed to metals had adverse effects on newborn parameters however they warranted caution due to the small case study and isolated details of the subjects. They additionally concluded that the primary cause of metal introduction to the placenta could be smoke.

    In a study more directed to negative pregnancy outcomes rather than human development by Erickson and Arbour on patheoetiological
    effects of particulate air pollution on fetal-placental development, it was determined that exposure of mothers to pollution contributed to adverse pregnancy outcomes. From a cell biology perspective, it is mentioned that oxidative stress and inflammation plays directly into the pathoetological determination of placentation. The generation of reactive oxygen species and the status of the maternal immune system significantly influences placental implantation and fetal development. It is suggested that the balance of pro- or anti-inflammatory environments in pregnancy is balanced and regulated to promote a healthy gestational environment. Chronic or acute inflammation in response to foreign substances, in this case toxic endogenous particulates, can cause signaling of cellular processes such as oxidative stress, proinflammatory markers, and ischemia. The study mentions cytokine production of interleukins IL-1beta, IL-6, and tumor necrosis factor, which recruit neutrophils to affected tissues. The generation of proinflammatory enzymes such as nitric oxide thus can affect tissues negatively via oxidative stress. It is evident that there can be
    adverse pregnancy outcomes that bear public health urgency.

  • Stephanie Michael

    The article above highlights particulate matter’s effects, obtained from traffic-associated air pollution, on the placenta. The placenta’s significance as the fetus’s lifeline and the toxins in the particulate matter are discussed in the article. Most importantly, however, this article identifies the immune system’s role in allowing these particulates’ uptake through phagocytic cells macrophage and trophoblasts, thus permitting build-up of particulates on the placenta’s fetal side. Macrophages are effector cells of the innate system, and during pregnancy, trophoblasts are significant components of the innate system. As a result of their phagocytic nature, macrophages and trophoblasts recognize, phagocytosis, and eliminate invaders. Therefore, from this knowledge, my question is as follows: given the immune system’s mechanisms, why is there a build of particulates on the placenta’s fetal side? How does the uptake of such particulates affect the development of the immune system? The obvious answer to this question points to the development and maturation of the immune system during early fetal life. Although the timeline for the development and maturation of the immune system has yet to be identified, studies have discovered the age of 7 – 8 when the immune system fully develops. Because fetuses’ immune system is in its beginning stages, fetuses are susceptible to infections by pathogens. So, what occurs after particulates uptake that results in the build-up in the placenta?

    Based in Murcia, Spain, the NELA study investigated how the developing fetal immune system was affected by exposure to traffic-related air pollution (TRAP). Researchers exposed participants to long-term and short-term levels of nitrogen dioxide (NO2), particulate matter (PM2.5 and PM10), and ozone (O3). Cord blood, the blood contained in the placenta and umbilical cord, immune cells were measured. In response to increased prenatal exposure to TRAP, there were a decreased counts of natural killer (NK) cells, cytotoxic T cells, and regulatory T (Treg) cells in the cord blood. As a result, the immune system’s development is impaired, and the fetus is susceptible to pathogens, which are the TRAP particulates. Assuming the mechanisms are similar for women studied in the above article, the defective immune system cannot eliminate the particulates from the cord blood, i.e., the placenta. Thus, explaining the build-up of particulates on the fetal side of the placenta. As we all know, the immune system plays a significant role in protecting the body from diseases, illnesses, and other infections. Though effective at its role, the immune system’s proper functioning has been confirmed to depend on different aspects, including genetics and fetal development events. Based on research and the article of discussion, I agree that proper actions must be taken to address the increased exposure of pregnant women, living specifically in urban areas, to particulates from air pollution. It is essential to understand that human life should not be put at risk at the expense of economic profits. Yes, the industries responsible for air pollution have proven to be influential in the development of countries. However, eco-friendly methods must be designed to protect humans, animals, and nature.

  • Marilyn M

    Hi Kesha,

    Thank you for the well thought out and written post. I agree that air pollution is a serious environmental health risk for both current and future generations. I was not able to find a study that demonstrated a way to clear air pollution from the placenta but I did find another study that showed that air pollution can have effects on the fetus as early as 4-6 weeks gestation so my assumption is that there is no way to reverse the exposure once it occurs.


  • Marilyn M

    This post is interesting to me because it lines up with what we know about how urban living affects the physiology of nonpregnant humans. For example, one study ( shows how urban living is tied to cardiovascular disease due to changes in lifestyles that human evolution has not quite caught up with. This study is further expanding on that idea by showing how urban lifestyles affect us even before we are born.

    Reducing pollution and increasing green spaces will benefit future generations by preventing carbon particle exposure.

    • Andrew Ho


      This was a good read, thank you for sharing. ALthough it seems like an obvious thought – the favoring of “correct” lifestyles is important in preventing cardiovascular disease – it was a reaffirming read that emphasizes diet, physical exercise, and other psycho-socio-economic factors is important in remaining healthy and battling risks for cardiovascular disease. It would be of great interest to see if a “correct” lifestyle in pregnant women could combat effects of urban pollution on gestation/pregnancy outcome. Discussed by Panasevich et. al. in 2016., there was a statistically significant negative association between pregnancy exposure to NO2 and birth weight, demonstrating that exposure to pollution during pregnancy can negatively effect birth weight and fetal development. It would be interesting to see if various life-style decisions in urban environments could combat the negative effects of air pollution.

  • Ray Kinney

    City environments are typically highly polluted with the toxic metal lead, which is legacy from leaded paint degradation, leaded gasoline dispersal, and abrasion of lost vehicular lead wheel weights on pavement. Much of this lead contaminated dust becomes air borne to have greatly increased body uptake through the lung route, in addition to the ingestion and even the skin penetration dermal routes. Yes, escaping to cleaner environments can be very important for public health, but sadly, not even a financial possibility for millions of people that are then continuing to accumulate pollution and suffer devastating harm accumulating over time.

    • Sharon Lackwood

      Hello Ray,

      Thank you for your insightful post. I would have to agree that even though mothers may know about the dangers of air pollution and the effects that it could potentially have on their children they may not have the finances to get up and move to a more rural area with less air pollution. Furthermore, your comment about how air particles can enter through the skin caught my eye and I decided to do a little bit of research. I found it fascinating how air pollution can damage skin in a similar way as UV rays from the sun, they both create reactive oxygen species (ROS), however, with air pollution the ROS stick to the skin while it does damage and allows for more damage because it does stick. Air pollution can cause accelerated skin aging as well as inflammatory and allergic skin reactions such as eczema, atopic dermatitis, psoriasis and many more. This opens a new door to maybe blaming autoimmune conditions such a Steven Johnson’s syndrome, TENS and atopic dermatitis that are seen at birth on air pollution.


  • Kesha H.

    This article discusses the dangers of particulate matter in pregnant women. This particulate matter from polluted air enters the mother’s system and lodges itself in the placenta. The placenta contains two umbilical veins and one umbilical artery connecting the mother and the child. The fetus is able to receive nutrients, oxygen-rich blood, and immune cells through the blood vessels in the placenta. This particulate matter can, therefore, compromise the development of the fetus once it infiltrates the placenta. Knowing this, I ask the question: Is there any way to reduce the amount of air pollution being inhaled by the mother or increase the clearance of these reactive substances in the lungs before it reaches the placenta? Are there any lasting defects for children born in highly polluted areas?

    One way to reduce the amount of air pollution that a mother inhales is to relocate. This solution is not always feasible due to financial difficulties. Many people are not able to leave the cities that they are currently residing in due to moving costs or even lack of financial/ emotional support. To increase the clearance of the particulate matter, the article mentions the presence of macrophages in the placenta. Although these cells are doing their best to clean the placenta, the toxins from the air are also affecting the mother’s metabolism and cardiovascular system. One study even noted that during the first trimester pregnant women faced an increase in preeclampsia, gestational hypertension, and preterm delivery. These air pollutants stimulate an inflammatory immune response due to the release of reactive oxygen species enhancing the response of several cells such as the macrophages, dendritic cells, and T cells leading to immune dysfunctions. Overall, air pollution is a serious environmental health risk that is affecting not only us but the future generation to come.

    • Kesha H

      In addition to my previous response, the placenta is not impenetrable to the particulate matter. This was proven in an article by Bove et al. where they experimented with carbon particle transmission to the fetus via the placenta. After mothers were exposed to ambient black carbon(BC), the placentas were biopsied after birth to determine the presence of BC. There are even studies that link the presence of air pollutants to several metabolic dysfunctions including the gut microbiome. The placental macrophages may become overwhelmed due to the particulate matter entering the placental tissues. This can lead to hypersensitivity reaction which leads to the attraction of other immune cells such as dendritic and a variety of T cells. Due to the immune response and release of inflammatory signals, this causes the mother to experience gestational hypertension. The increase in inflammatory cytokines causes blood vessels to become leakier causing increased fluid causing this hypertension. This increased blood pressure can cause preeclampsia in the worst-case scenario. Due to the low immune system in the fetus, if this particular matter enters the fetal circulation there won’t be enough immune cells to fight off the reactive oxygen species. This is the reason that there can be birth defects. Normally the mother supplies the fetus with antibodies and a few immune cells. However, since the mother is still fighting off the particulate matter her immune cells are hosting an immune response. There are also T regulatory cells created to help control the inflammatory response to this particulate matter, which are seen as an exogenous invader.


  • Ali Nayebi

    The article describes how particulate matter is discovered to be in placental cells. This particle matter contains chemicals found in vehicles’ exhaust, mentioning how during development, inhalation of this particulate matter can harm the unborn child and damage their brain and heart. My question is: what would happen if a child is born in a circumstance where the mother is living in a densely populated area that is thick with pollution, and they are unable to leave that area due to their economic or financial status? How would these living conditions affect the function of her macrophage and trophoblast cells? My best guess is that the baby could suffer permanent damage to their lungs and develop breathing problems early on in their life, as sad as that may sound. However, I am not sure as to the extent to which macrophages and trophoblasts can help protect the unborn child in this situation. Macrophages function in the body by detecting harmful pathogens and destroying foreign bacteria through phagocytosis. Trophoblasts are vital in providing nutrients to an embryo by being the protective outer layer of a blastocyte, which helps an embryo develop in the placenta. That being said, depending on the quantity of vehicle exhaust the mother is inhaling and for how long she has done this, some damage could be permanent to the unborn baby’s cells so that their function is slowed and not as effective. We can only hope that financial assistance can be provided to a mother who is in this type of situation. Maybe a study can be done to compare women living in urban and rural areas and how their placentae are affected by traffic exhaust?

    For example, a study conducted in Sweden demonstrated how pregnant women are threatened by ambient air pollution and how particulate matter can enter the mothers’ circulation and reach the placenta, possibly damaging the unborn child’s health effects. The damage of the particulate matter showed how the trophoblast cells are affected. Harm is inflicted on the women and their placenta, but how much and to what extent? In 2019, Mary Familari and Lena Erlandsson described in detail how exposure to this particulate matter between 2 to 7 days could lead to a decrease in cell growth and a changed protein expression. This alteration in the expression of proteins affects many different functions in the body, including the cell’s ability to survive, a molecule’s ability to transport effectively, as well as inflammation occurring. Familari and Erlandsson conclude that these low levels of particulate matter in urban areas in Sweden lead to trophoblast cells having their function affected. We know that if these proteins’ cellular processes are affected, this can lead to possible growth defects and cause issues with inflammation and difficulty in particles being taken up by endocytosis. To wrap this up, we see that environmental effects such as air pollution or car exhaust can affect various cells, like Macrophages and Trophoblasts, in the body. The damaging effects occurring in the differentially expressed proteins can lead to disruption of immune function, affecting not only the mother but also the unborn child in the womb.

    • Kesha H.

      Hello Ali,

      I do agree that the developing fetus may have deficits due to the particular matter. However, these deficits are not just consolidated into the lungs. In utero, the child is not using its lungs because the placenta provides oxygenated blood that is distributed throughout the fetal circulation. The child will have issues with organ development such as the brain, heart, liver, and lungs. Out of all of these, the brain is the most concerning. These congenital defects are the major cause of increased infant morbidity and mortality rates in this case. Air pollution is a major global health problem. There has been a Clean Air Act implemented to reduce air pollution in certain areas to reduce the morbidity and mortality rate. There are also several organizations working to improve air quality by planting more trees to improve air circulation.

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