We all must have come across the phase: this is why women live longer than men. These are all over the social media, where men are performing more often than not, some experiments, without gears, just for fun, "in the name of science". The caption reads: this is why women live longer. However, is there really a science to it, other than the fact that women choose to do things more safely?

In the United States, women have a life expectancy of about 80, whereas men have 75. Women outlive men and this holds true regardless of the country women live, the money they make, and other factors. In fact, it is true for most other mammals too.

Dr Dena Dubal, a professor of neurology at the University of California, San Francisco told the New York Times, "It is a very robust phenomenon all over the world, totally conserved in sickness, during famines, during epidemics, even during the times of starvation."

But what are the reasons? These reasons are often more complicated and less established. It is important to note that only because women are outliving men does not mean they are living a better life. In fact, women tend to have shorter health spans, which means the number of healthy years in a person's life is less in women than men, confirmed Bérénice Benayoun, an associate professor at the U.S.C. Leonard Davis School of Gerontology.

As per a 2021 study titled, Sex differences in frailty: Comparisons between humans and preclinical models, found that women are more physically grail than men in old age. They are also more vulnerable, especially after menopause and are at more risk of developing cardiovascular issues and Alzheimer's disease because of age.

The key is in figuring out what makes one sex more resilient or vulnerable.

Genetics

For things which do not find easy explanations, scientists look for their answers in genes. Many research, including a 2020 study titled, The sex with the reduced sex chromosome dies earlier: a comparison across the tree of life, suggests that the XX set of female sex chromosomes may impact longevity. However, there has not been any clarity on how it affects longevity.

Another 2018 study titled, Female XX sex chromosomes increase survival and extend lifespan in aging mice, which was conducted by Dr Dubal's lab, looked at genetically manipulated mice with different combinations of sex chromosomes and reproductive organs. It was found that those with two X chromosomes and ovaries lived longest, followed by mice with two X chromosomes and testes. Mice with XY chromosomes had shorter life spans.

"There was something about the second X chromosome that was protecting the mice from dying earlier in life, even if they had testes. What if there was something on that second X chromosome that was in some ways a sprinkle of the fountain of youth," says Dr Dubal. While scientists have not yet looked at this factor in humans, Dr Dubal suggests that humans have the same hormones and sex chromosomes, and similar reproductive system that could corroborate the similar findings in people.

Hormones

Plenty research has shown that estrogen is responsible for longevity also effect on the immune system. The data also shows that before menopause, the female immune system tends to do better. In fact Dr Benayoun said that males tend to do much worse in response to infection.

Another 2017 study titled, Ages at Menarche and Menopause and Reproductive Lifespan As Predictors of Exceptional Longevity in Women: The Women's Health Initiative, found that women who experienced menopause later in life over the age 50 lived longer than those who experienced it earlier.

Lifestyle and Behavior

There are also disparity in behavioral patterns between men and women. This includes smoking, drinking heavily, which can contribute significantly to mortality. Women also have more "health promoting behavior", believe experts. Women are also more likely to socialize than men and thus it protects them from detrimental effects of social isolation and loneliness. In fact, a 2023 analysis published in Jama Network, titled, Widening Gender Gap in Life Expectancy in the US, 2010-2021, found that women are less likely to die by drug overdose or suicide.

Rabies is a fatal viral disease that spreads to humans through the saliva of infected animals. It targets the central nervous system, and nearly 99 percent of human cases are linked to infected dogs. A recent *Lancet* study found that about 5,726 people still die from rabies each year, even though overall deaths have declined over time. This is why prompt medical care after a dog bite or scratch is critical. Most people believe the rabies vaccine taken after a bite is enough. What many do not realise is that a pre-exposure prophylaxis vaccine is also available and can be taken even before a bite occurs. So why does this vaccine matter, and how does it actually protect you?

What Is A Rabies Pre Exposure Prophylaxis Vaccine?

A rabies pre-exposure prophylaxis, or PrEP, vaccine involves a set of shots given before any possible contact with the rabies virus. It is mainly recommended for people at higher risk, such as veterinarians, animal handlers, laboratory workers, and travellers visiting regions where rabies is common. While PrEP does not remove the need for treatment after a bite, it makes post-exposure care simpler. People who have received PrEP need fewer follow-up injections and do not require rabies immunoglobulin, which can be hard to access in emergencies and may save crucial time.

How Can Rabies Pre Exposure Prophylaxis Vaccine Protect You?

According to Dr Deepa Aggarwal, who shared insights on her Instagram account, the rabies pre-exposure prophylaxis vaccine prepares the immune system in advance. It helps the body develop antibodies before any exposure occurs. If a vaccinated person is bitten later, they need only two booster shots and no immunoglobulin. The immune response is quicker, lowering the risk of the virus spreading to the brain. This is especially important for people at high risk or in situations where medical treatment may be delayed.

Rabies Pre Exposure Prophylaxis Vaccine: How It Works?

• Introduces Antigens: The vaccine contains an inactivated form of the rabies virus, which safely exposes the body to its antigens.
• Builds Memory: The immune system learns to recognise these antigens and creates antibodies along with memory cells.
• Rapid Response on Exposure: If exposure happens later, these memory cells act fast, producing antibodies that stop the virus before it can cause infection.

CDC Guidelines On Rabies Pre Exposure Prophylaxis Vaccine

The Advisory Committee on Immunization Practices, or ACIP, has updated its recommendations for rabies PrEP.

• A two-dose PrEP schedule has now replaced the earlier three-dose schedule and offers protection for up to three years. Options for maintaining protection beyond three years are also outlined on their website.
• The minimum antibody level used to decide whether a booster is needed has been revised and standardised.
• Many people who previously needed antibody testing every two years now require only a one-time titer check, followed by a booster if levels are low, or in some cases, just a one-time booster.

Who Should Get The Rabies Pre Exposure Prophylaxis Vaccine?

While the vaccine can benefit anyone, rabies pre-exposure prophylaxis is mainly advised for people with frequent or high risk of exposure. This includes veterinarians, animal handlers, wildlife workers, laboratory staff, and travellers to areas where rabies is widespread. The vaccine makes treatment after a bite easier by reducing the number of shots required. However, health authorities stress that while PrEP offers protection, it does not replace full post-exposure treatment after a confirmed bite, as advised by the CDC and WHO.

Air quality in Delhi remains toxic, despite the GRAP !V measures implemented in the national capital. Today, Delhi recorded an AQI of 358, this remains under 'very poor'. As per the Central Pollution Control Board (CPCB), the AQI was recorded at 442 in Ghazipur, 409 in ITO, and 447 in Palam, all under 'severe' category.

While we have long known that pollution impacts lung and respiratory health, but it can impact beyond that, including causing severe menstrual cramps.

What Proves That Air Pollution Impacts Menstrual Cramps?

A study published in Frontiers in Public Health, explored the data of 2,96,078 women and girls between the age of 16 to 55 years in Taiwan and correlated it with the long-term air pollution data between 2000 and 2013. None of these women had any history of dysmenorrhea before the survey had began. Dysmenorrhea is a common gynaecological condition that impacts 16 to 91% of people in their reproductive age. The signs and symptoms include painful and severe periods that are results of hormonal imbalances.

The results showed that during the 13 years, 4.2% women and girls were diagnosed with dysmenorrhea for the first time. The study concluded that risk of developing dysmenorrhea was up to 33 times higher among women and girls who lived in areas with the highest levels of air pollutants.

Professor Hsu, who conducted the study said, "Our results demonstrate the major impact of the quality of air on human health in general, here specifically on the risk of dysmenorrhea in women and girls."

The pollutants in questions are nitrogen oxide, nitric oxide, nitrogen dioxide, carbon monoxide, and particle smaller than 2.5 µm in diameter (PM2.5).

Also Read: Delhi Is a Gas Chamber Where Nothing Comes In or Goes Out, Says Expert; Neighboring States Not to Blame for AQI

How Air Pollution Shapes Menstrual Health - Its Impact

The public health impact of air pollution is more layered and gendered than it often appears. Over the years, a growing body of research has begun to link polluted air with menstrual health problems. A 2018 study found that teenage girls exposed to higher air pollution were more likely to experience irregular periods and took longer to develop regular cycles during adolescence and early adulthood. Other studies have connected air pollution with longer menstrual cycles, increased stress, reproductive health issues, and even changes observed during lockdown periods. Conditions such as infertility, metabolic syndrome, and polycystic ovary syndrome have also been associated with prolonged exposure to polluted air.

These findings challenge the idea that menstrual health is purely biological. Instead, it is deeply influenced by social and environmental conditions, including income levels and where a person lives. In the present study, researchers observed that younger women, women from lower-income backgrounds, and those living in highly urbanised areas faced a higher risk of developing dysmenorrhea or painful periods. Among all factors studied, long-term exposure to high levels of PM2.5 emerged as the strongest contributor. PM2.5 refers to fine, inhalable particles commonly found in polluted air that can penetrate deep into the body.

The concern becomes sharper in the Indian context. In 2019, India recorded the highest PM2.5 levels globally. The study highlights clear differences in menstrual experiences between women and girls living in urban versus rural areas. Those in low-income and densely populated urban regions, where exposure to air pollution is often highest, showed a significantly greater risk of dysmenorrhea.

This health burden is further compounded by period poverty, which continues to affect large sections of rural India and many other countries. Limited access to sanitary products, lack of awareness, and social stigma mean that many girls and women already miss school and work during their periods. Increased menstrual pain linked to environmental factors like air pollution only deepens these challenges.

A 2017 study underlined the importance of identifying environmental influences on the menstrual cycle from a public health perspective, noting potential long-term consequences such as infertility, reproductive cancers, osteoporosis, and metabolic disorders.

With winter setting in, Delhi and the NCR are once again dealing with a sharp rise in air pollution, with AQI levels often slipping into the “very unhealthy” category. Hazy mornings, dense smog, and a steady increase in breathing problems have made clean air feel out of reach for many residents. As a result, people are relying more on air purifiers indoors and masks outdoors.

Still, not everyone knows how to use these measures correctly. We spoke to pulmonologist Dr. Vijay Kumar Agrawal, Director of Pulmonology and Critical Care at Yatharth Super Speciality Hospital, Faridabad, who shared a few important points that can help protect your lungs even inside your home.

What Is An Air Purifier?

An air purifier is a device designed to improve indoor air quality by filtering out pollutants such as dust, pollen, pet hair, smoke, and mold spores. It works by pulling air through filters like HEPA or activated carbon, or by using certain technologies, and then releasing cleaner air back into the room.

This process can help reduce triggers for allergies and asthma and make breathing easier. While air purifiers are particularly helpful for people with respiratory conditions, growing pollution levels have made them a common household choice even among otherwise healthy individuals. That said, simply owning an air purifier is not enough. There are a few key things you should keep in mind while using one.

Select Air Purifier With HEPA Filter Only

Dr. Agrawal advises choosing an air purifier that uses a HEPA filter. Many people unknowingly use air purifier that release ozone or free radicals, which can increase the risk of breathing problems, irritation, coughing, and shortness of breath. According to him, “Air purifiers with HEPA filters are ozone-free and safer because they do not emit harmful particles or ozone into the air.”

Always Maintain An Ideal Indoor Humidity Level- 40-50%

To reduce the impact of viruses, indoor pollutants, and dryness on the body, it is best to maintain indoor relative humidity between about 40% and 60%. Dr. Agrawal explains that excessive use of air purifiers can lower humidity levels indoors, leading to dryness. “Low humidity can irritate the airways and may worsen respiratory issues,” he says.

Keep Your Air Purifier 2-6 ft Away From You

Experts recommend keeping an air purifier at a distance of around 2 to 6 feet from where you sit or sleep. Placing it within this range helps clean the air more effectively in your breathing zone, especially in spaces like bedrooms or offices. Dr. Agrawal notes, “Keeping the air purifier at an appropriate distance helps reduce PM2.5 and PM10 levels, along with other particles such as pollen, mold spores, and certain bacteria around us.”

Dont Burn Incense Sticks And Mosquito Coils With An Air Purifier In The Room

In many Indian households, burning incense sticks or mosquito coils indoors is common. However, these release chemical irritants that can be harmful to the lungs. Using them in the same room as an air purifier defeats the purpose of cleaner air and should be avoided.

Dont Tightly Close Windows And Doors

Proper ventilation is still important, even when using an air purifier. Dr. Agrawal recommends keeping at least one window or a small door slightly open to allow fresh air exchange. This helps ensure a supply of oxygen from outside and prevents indoor air from becoming stale.

Dr. Agrawal adds that while using an air purifier is generally safe and even long-term use is not harmful, following these precautions is essential to truly protect your lungs and maintain healthier air indoors.