The link between infertility and air pollution

Air pollution is responsible for countless health issues. These health issues span the entire human body, impacting nearly every body system and even individual organs. Air pollution-caused diseases range from respiratory diseases (allergies, asthma, COPD, pulmonary embolism), multiple types of cancer (especially lung cancer), cardiovascular disease, mental health conditions, diabetes mellitus, and more. Studies are finding that air pollution also affects reproductive health, causing decreased fertility rates in both men and women. Read on to learn more.

The effects of air pollution exposure on infertility

How poor air quality impacts infertility

In males

Throughout the past two decades, a significant reduction in sperm quality has been observed throughout industrialised countries. A 1995 study on men in Paris already expressed concerns: from 1973 to 1995, the mean concentration of sperm had decreased by 2.1% annually¹. Motility had also decreased. Another study in 2003, less than a decade later, analysed semen quality in 85 men who worked at motorway tollgates where road traffic pollution exposure is extremely high. Compared to the control group, men working at tollgates experienced ‘significantly lower’ results in total sperm motility, forward progression, functional tests, and sperm kinetics². Similar results were found in a 2009 study on men exposed to nitrogen dioxide (NO2), a common air pollutant, at work³.

A 2020 study out of China furthered these findings. Exposure to common air pollutants like carbon monoxide (CO), nitrogen dioxide (NO2), ground-level ozone (O3), and particulate matter (PM10 and PM2.5) had negative effects on sperm count, with exposure to the latter having the largest impact on sperm count. Men exposed to ozone were observed to have a significant sperm motility decline in the later stages of sperm development⁴.

The above studies all have the same consensus: environmental factors like air pollution exposure play a role in fertility, and protections must be put in place.

In females

A 2018 study on laboratory mice in Sao Paolo, Brazil, a city with a high level of ambient pollution, found that mice who experienced air pollution exposure bore a significantly-reduced number of births per mouse and the success rate of embryo implantation was significantly decreased. Furthermore, female mice exposed to ambient air pollution (mostly from road traffic) also demonstrated:

• Increased number of days in estrus
• Reduction in ovarian antral follicles
• Increase in time to mating
• A significant decrease in fertility index (number of pregnant females to number of total females)⁵

In a heavily-polluted region in the Czech Republic, a 2000 study showed that exposure to particulate matter (notably PM2.5) leads to a decrease in fecundability in women. In fact, each increase in 10 μg/m3 in PM2.5 concentration was associated with a 22% decrease in fecundability and spontaneous pregnancy. Results were similar for women exposed to ambient NO2 during the first two months of unprotected intercourse and attempted conception⁵.

A 2018 systematic review of literature on air pollution’s effects on female reproductive health analysed the impact of air pollution exposure by specific pollutant (on women undergoing IVF and those of the general population):

• NO2 exposure
• IVF: associated with lower live birth rate from embryo transfer to pregnancy test
• General population: significant decrease in fecundability ratio per increase of 10 μg/m3; miscarriage rate significantly increased
• CO exposure
• General population: associated with stillbirth in second and third trimesters
• O3 exposure
• IVF: associated with detrimental effect on live birth rate from embryo transfer to date of live birth
• General population: no significant difference
• PM2.5 exposure
• IVF: decreased conception rate
• General population: adjusted fecundability and spontaneous pregnancy ratio significantly decreased with each 10 μg/m3 increase
• PM2.5-PM10 exposure
• General population: significant reduction of spontaneous fertility rate
• PM10 exposure
• IVF: higher risk of miscarriage in women with higher exposure (level of >56.72 μg/m3)
• General population: significant association with early miscarriage for women with higher exposure (level of >56.72 μg/m3)
• SO2 exposure
• IVF: no significant difference
• General population: significant reduction in spontaneous pregnancy in first unprotected menstrual cycle for couples exposed in second month before conception
• Organic solvent exposure (hexane, hexane isomers, toluene, methyl ethyl ketone, acetone, ethyl acetate, isopropyl alcohol)
• General population: reduced fecundability density ratio for low and high exposure levels
• Traffic pollutant exposure
• General population: increased risk of miscarriage for women exposed to traffic pollutants within 50 m and those living close to a major road
• Coal combustion pollutant exposure
• General population: increased rate of miscarriage⁶

Sources of air pollution that cause or contribute to infertility

As seen above, a variety of air pollutants exist that may either be a direct cause or contribute to decreased fertility in both men and women. Air pollution is generated through many different sources, most of which involve the combustion of fossil fuels that emit fine particle pollution (road traffic, industrial emissions, and domestic burning of wood or natural gas). These pollutants enter indoor spaces and become trapped which is why indoor spaces experience pollution levels 2 to 5 times higher than outdoor spaces. Seeing as we spent 90% of our time indoors, the risk of exposure is high.

Air pollution is also generated through the use of volatile organic compound (VOC)-emitting products found in the home and professional spaces including glues, adhesives, paint, textiles, furniture, pesticides and fungicides, candles, air fresheners, cleaning and sanitising products, etc. Cigarette smoke emits both fine particle pollution (particulate matter) and VOCs, in addition to radioactive substances.

How to protect ourselves

Outdoor solutions

It is often difficult to protect ourselves from outdoor air pollution. When the Air Quality Index (AQI) is high due to high fine particle pollution or heavy concentrations of allergens, it is best to avoid time spent outside to the best of your ability. If you must go outdoors, it is recommended to wear a mask with high-quality filtration (like KN95-type masks). Take extra care of your health when passing through heavily polluted areas (near motorways or busy roads), construction areas (construction dust is a respiratory irritant), and industrial areas (multiple types of air pollution are emitted at these sites), to name a few.

Indoor solutions

Luckily, it is easier to control the quality of your indoor air at home and in commercial buildings in order to protect the health of the occupants of those spaces. Devices like air purifiers and air scrubbers are designed to clean your indoor air and reduce pollution concentrations, keeping you safe from the dangers of indoor air pollution. Remember: indoor air is 2 to 5 times more polluted than outdoor air and consists of all the same pollutants that are found outdoors.

Air purifiers and air scrubbers, depending upon the model and quality of course, both serve the same role: they are capable of removing multiple types of air pollution like fine particle pollution (PM10, PM2.5, and PM0.1), germs (bacteria and viruses), allergens (dust, dust mites, pollen, pet hair and dander, and mould and spores), chemical pollution (VOCs and ozone), and more. Air purifiers are typically more adapted to homes and offices, whereas air scrubbers are more heavy-duty and useful in heavily polluted industrial settings. Certain air purifiers, like Eoleaf’s, remove 99.97% of all types of air pollutants down to 0.01 microns in a single pass with its proprietary 8-step air filtration method!

It is important to keep in mind that all air purifiers and air purification devices in general require maintenance and care in order to ensure reduced air pollution exposure. Be sure to follow the manufacturer’s instructions regarding replacing filters in air purifiers and the replacement of parts.

Benefits of Eoleaf’s air purifiers

The air purification market is flooded with devices of varying quality. It may be difficult to find the best device for your needs. Eoleaf’s devices are unique on the market: with their 8-step air purification system, there is no need for the consumer to settle on which types of air pollutants are removed from their indoor air. Our devices do it all!

Improve air quality

Eoleaf devices filter all three of the main types of air pollution: fine particle pollution, biological pollution, and chemical pollution. Our 8-step air filtration system includes:

• Pre-filter: removes larger particles like hair, dust, and fibres and protects other layers of the filter from clogging
• Bamboo filter with an antibacterial coating: targets particle pollution
• Medical-grade HEPA H13 filter: combats fine and nanoparticles, removing 99.97% of all pollutants down to 0.01 microns in a single pass
• Activated carbon filter: targets chemical pollution (carbon monoxide, ozone, VOCs like formaldehyde and benzene) and unpleasant odours
• Photocatalysis: depollution method that further targets VOCs and gases
• UVC sterilisation: extremely effective against germs (bacteria and viruses)
• Ionisation: particularly efficient in removing smoke and fine particles

Remove unpleasant odours

In addition to combatting the three main types of air pollution, Eoleaf devices also remove unpleasant odours. These odours may be generated by cigarette smoke, gases in the home, pets, kitchen or bathroom odours, VOCs, and other sources in your indoor environment.

Room size compatibility

Two metrics should be considered before choosing your air purifier: CADR and ACH. An air purifier’s Clean Air Delivery Rate (CADR) determines the volume of filtered air it is capable of efficiently producing. CADR is an industry standard that allows consumers to compare filtration efficiency between brands. The higher the CADR, the more effective an air purifier is! Air Changes per Hour (ACH) is another important value to consider. The industry recommended standard is an ACH rating of 4 or 5 (meaning that an air purifier completely replaces the air in your space 4 or 5 times in one hour). In order to ensure that the air in your space will be completely filtered, ask your air purifier’s manufacturer to calculate the ACH rate for you using the specific square footage of the room in which you plan to install your device.

Frequently asked questions

How does air pollution cause infertility?

Different types of air pollutants have different effects on male and female fertility. Generally speaking, in males, sperm count and motility are both reduced as a result of air pollution exposure. In females, fecundity is reduced, as the likelihood of embryo implantation for women undergoing IVF. Read more in the above article for a detailed summary of relevant scientific studies.

Can infertility be caused by environmental factors?

Studies point to yes. Environmental factors, especially air pollution exposure, have been proven to impact and reduce fertility in men and women.

Does air pollution reduce sperm count?

According to multiple studies, yes, sperm count is impacted by exposure to certain air pollutants, especially particulate matter (PM10 and PM2.5), carbon monoxide (CO), nitrogen dioxide (NO2), and ground-level ozone (O3) have negative effects on sperm count. These pollutants also reduce sperm motility.

Does air pollution affect hormones?

Studies throughout the past two decades have shown that air pollution affects all body systems. It leads to diseases like respiratory diseases, cardiovascular disease, multiple types of cancer, mental health conditions, reduced productivity in the workplace and at school, and impacted fertility in men and women.

Resources

¹ Auger J, Kunstmann JM, Czyglik F, Jouannet P. Decline in semen quality among fertile men in Paris during the past 20 years. N Engl J Med. 1995 Feb 2;332(5):281-5. doi: 10.1056/NEJM199502023320501. PMID: 7816062.

² De Rosa M, Zarrilli S, Paesano L, Carbone U, Boggia B, Petretta M, Maisto A, Cimmino F, Puca G, Colao A, Lombardi G. Traffic pollutants affect fertility in men. Hum Reprod. 2003 May;18(5):1055-61. doi: 10.1093/humrep/deg226. PMID: 12721184.

³ Boggia B, Carbone U, Farinaro E, Zarrilli S, Lombardi G, Colao A, De Rosa N, De Rosa M. Effects of working posture and exposure to traffic pollutants on sperm quality. J Endocrinol Invest. 2009 May;32(5):430-4. doi: 10.1007/BF03346481. PMID: 19794293.

⁴ Huang G, Zhang Q, Wu H, Wang Q, Chen Y, Guo P, Zhao Q. Sperm quality and ambient air pollution exposure: A retrospective, cohort study in a Southern province of China. Environ Res. 2020 Sep;188:109756. doi: 10.1016/j.envres.2020.109756. Epub 2020 Jun 3. PMID: 32531526.

⁵ Carré J, Gatimel N, Moreau J, Parinaud J, Léandri R. Does air pollution play a role in infertility?: a systematic review. Environ Health. 2017 Jul 28;16(1):82. doi: 10.1186/s12940-017-0291-8. PMID: 28754128; PMCID: PMC5534122.

⁶ Conforti A, Mascia M, Cioffi G, De Angelis C, Coppola G, De Rosa P, Pivonello R, Alviggi C, De Placido G. Air pollution and female fertility: a systematic review of literature. Reprod Biol Endocrinol. 2018 Dec 30;16(1):117. doi: 10.1186/s12958-018-0433-z. PMID: 30594197; PMCID: PMC6311303.