If hand sanitisers kill 99.99% of germs, then who are those 0.01% who survive? There are three major kinds of germs which remain active even when you have used your sanitiser.

Norovirus

Among them, is the norovirus that causes diarrhoea and vomiting outbreaks in places like cruise ships and schools. It is superior to many other viruses because it has a protein capsid, which is resistant to the effects of alcohol.

Norovirus is a group of viruses that causes common illnesses and is also very contagious. It is especially active in the colder month and comes back seasonally. The first norovirus outbreak occurred in Norwalk, Ohio, USA, in a school in 1968, this is where it gets it name from.

Enterococcus faecium

The next on the list is enterococcus faecium, and it lives in the gut. As per a 2024 study titled Enterococcus faecium: evolution, adaptation, pathogenesis and emerging therapeutics, published in Nature journal, it is a Gram-positive bacterium that is a core member of the intestinal microbiota of humans and animals and an opportunistic pathogen that causes life-threatening infections, particularly among hospitalized patients. It mutates in a way that it absorbs carbohydrates and forms a gooey, slime-like substance called the biofilm, which makes it resistant to alcohol.

Clostridium Difficile

Another one is clostridium difficile. This is responsible for causing horrendous diarrhoea and vomiting in hospitalised patients. It also has a remarkable ability to respond to environmental stressors including alcohol gel by going to sleep. It produces spores and allows all metabolic activity.

Clostridium difficile (C. diff) is a type of bacteria that can cause colitis, a serious inflammation of the colon. Infections from C. diff often start after you've been taking antibiotics. It can sometimes be life-threatening.

Why Do You Label Read 99.99%?

Apart from the germs and pathogens, another reason why your label reads that it kills 99.99% is to avoid any legal hassles. If someone uses a specific product and falls sick, then the person cannot sue the company as the company did not give a 100% safety guarantee against the germs.

A better way to be healthy is always to clean your hands with soap and water and wear gloves wherever is possible.

As pollution season creeps back in Delhi, N95 masks outdoors and air purifiers are once again most likely to become the primary go-to protective measures for the public.

Both are known to lower exposure to harmful particles significantly, but neither can completely nullify the health risks of polluted air. So before you invest in an air purifier or buy a dozen N95 masks, understand how much you will be protected as you step out during smog everyday.

How Much Protection Does An N95 Mask Offer?

Also read: Delhi Pollution: What Are The Different Types Of Anti-Pollution Masks?

A properly fitted N95 respirator can filter at least 95% of airborne particles under standard environment. That makes it substantially more protective against fine particulate matter like PM2.5 than regular surgical or cloth masks.

But just wearing an N95 does not mean you are breathing toxins-free air. Its effectiveness depends heavily on fit. Gaps around the nose, cheeks or chin can let polluted air to bypass the filter.

An N95 also does not protect equally against every pollutant. It is designed primarily to filter particles, not gases like nitrogen dioxide or ozone. So if you spend most of your time outdoors during severe pollution, wear a well-fitted, certified respirator to reduce exposure.

Protection from PM2.5 is key as these particles are small enough to seep deep into your lungs and, in some circumstances, even cross over to enter the bloodstream. Long-term exposure to PM2.5 has been associated with cardiovascular disease, respiratory disease and other serious health problems.

Is An Indoor Air Purifier Enough To Tackle Outdoor Pollution?

The effectiveness of an air purifier depends significantly on the purifier, the size of the room and how it is used. A purifier equipped with a HEPA filter can remove fine particles from indoor air. When outdoor PM2.5 levels are high and polluted air enters homes through windows, doors and ventilation systems, this could be one of the best ways to protect yourself.

However, simply switching on a purifier in a large room does not guarantee clean air. The purifier needs to have sufficient clean air delivery rate (CADR) for the size of the room.

Keeping doors and windows closed during periods of extreme outdoor pollution can also help reduce the amount of polluted air entering. Filters need to be replaced according to the manufacturer's recommendations because a heavily loaded filter can reduce performance.

Also read: Delhi Air Pollution Is Back: What Days Of Poor AQI Can Do to Your Lungs

One of the limitations is that HEPA filtration primarily addresses particles. A purifier needs additional technologies, like an activated-carbon filter, to reduce some gaseous pollutants, and even then it cannot remove every pollutant completely.

For Delhi's pollution season, these two measures address different exposure issues. N95 masks help reduce inhalation of polluted particles while outdoors. Air purifiers help lower indoor concentrations of particulate matter. Using both can therefore provide greater protection than relying on either measure alone.

People with asthma, COPD, heart disease or other respiratory and cardiovascular conditions, as well as children and older adults, can be more vulnerable to the effects of air pollution.

Even healthy people can experience symptoms like coughing, throat irritation, wheezing, eye irritation and breathing discomfort when pollution levels rise.

Dry eyes are common among people who spend long hours on screens, and lubricating eye drops are often used for relief. But using the wrong drops, keeping an opened bottle for too long or even sharing eye drops can create problems.

Estimates suggest that up to 50% of adults experience dry-eye symptoms, making artificial tears a common part of self-care. But persistent symptoms should not simply be treated indefinitely without identifying the underlying cause.

So, how often can you use eye drops, and what should you keep in mind?

We spoke to Dr. Ritika Sachdev, Director at Centre for Sight, New Delhi, to understand the common mistakes people make while using eye drops.

Eye Drops For Dry Eyes: When Should You See A Doctor?

Dr. Ritika said persistent or bothersome dry eye symptoms should be assessed by a doctor because dryness can have several causes.

These may include:

• Eyelid inflammation
• Allergies
• Contact lens use
• Makeup
• Incorrect spectacle power causing eye strain

“Sometimes even not wearing your right spectacle power contributes to eye strain which can be misread as dry eye,” she said.

Lubricating drops can help support dry eyes, but prolonged use should be discussed with an eye specialist.

Using Eye Drops For Long? Check For Preservatives

Also read: Eye Drop Recall: Nearly 750,000 Products Pulled Over Sterility Concerns in US

Several eye-drop products have been recalled in the US in recent years over contamination and other safety concerns. This makes proper storage, handling and hygiene particularly important when using eye drops.

Dr. Ritika cautioned that some eye drops contain preservatives that may worsen dryness when used for a long time.

“Many of the eye drops have preservatives which if used over a long period of time actually cause more dry eye,” she said.

According to her, preservative-free drops or those with very mild preservatives may be preferable for people who need regular use.

Don't Keep An Open Eye Drop Bottle Forever

"Once opened, an eye drop bottle can become contaminated if it is not handled or stored properly," Dr. Ritika said.

The expert advised:

• Note the date when you open the bottle.
• Follow the product's storage instructions.
• Do not let the bottle tip touch your eye.
• Discard the bottle according to the manufacturer's instructions.
• Do not continue using an opened bottle indefinitely.

“Once the bottle is open, it often may get contaminated,” she said. “If it gets contaminated, it is a source of infection.”

Read More: Andrew Huberman’s Sleep Trick: Can Eye Movements Help You Fall Back Asleep?

How Many Eye Drops Should You Use?

More drops do not mean more relief.

“The capacity of the eye is only one drop,” Dr. Ritika said.

Putting two or three drops at once can cause the excess to spill onto the surrounding skin and simply waste the product. One properly administered drop is generally enough at a time, she said.

Avoid Squeezing Your Eyes After Using Drops

Dr. Ritika said people often squeeze their eyes tightly after putting in drops because they think this will keep the medicine inside. But squeezing can push the drop back out.

Instead:

• Gently pull down the lower eyelid.
• Place the drop into the eye.
• Avoid touching the bottle tip to the eye.
• Do not squeeze the eyes tightly immediately afterward.

Why Do Eye Drops Sometimes Reach The Throat?

Some people experience an unpleasant sensation in the throat after using medicated eye drops.

Dr. Ritika explained that tears can travel from the eye through the tear duct to the nose and then the throat.

She suggested gently pressing near the inner corner of the eye for a while after applying the drop to reduce this drainage.

Never Share Your Eye Drops

Sharing eye drops may seem harmless, particularly within families, but Dr. Ritika advised against it.

If the bottle tip accidentally touches an infected eye, the bottle can become contaminated and potentially transmit infection when used by someone else.

“Eye drop is something that is for your personal hygiene and it should therefore be kept by you and used by you,” she said.

Clear vision does not always mean that the eyes are healthy. Diabetes can damage the retina the sensitive layer at the back of the eye long before a person notices any change in eyesight.

This happens because high blood sugar can weaken the blood vessels that supply the retina causing them to leak fluid or blood.

What happens as retinopathy progresses?

Diabetic retinopathy is a complication in which high blood sugar damages the blood vessels. In the stages these vessels may swell or develop small areas of bleeding without affecting vision.

As the condition advances, reduced blood supply can cause abnormal new blood vessels to grow. These vessels are fragile. May bleed into the vitreous the clear gel inside the eye. In some cases, scar tissue can pull the retina away from its normal position leading to retinal detachment and potentially permanent vision loss.

Also read: Eye Drop Recall: Nearly 750,000 Products Pulled Over Sterility Concerns in US

How diabetes affects central vision

Diabetes can also affect the macula, the part of the retina responsible for sharp detailed vision. When fluid builds up in this area it can cause macular oedema and gradually affect the quality of vision.

It may lead to:

• Distorted central vision
• Difficulty reading or recognising faces
• Problems with activities that require clear detailed vision, such as driving

Diabetic macular oedema can occur at different stages of diabetic retinopathy and does not always cause symptoms in the early stages.

Also read: Eye Twitching: Is It Just Stress Or Something Serious?

Who is at risk?

The likelihood of eye damage increases with the duration of diabetes and poor blood sugar control. High blood pressure, abnormal cholesterol levels and kidney disease can further increase the risk.

Women with diabetes may also need monitoring during pregnancy as hormonal and blood sugar changes can worsen existing retinal disease.

Why regular eye examinations matter

On World Sight Day, doctors recommend that a routine eyesight test may not detect damage to the retina. People with diabetes should therefore undergo an eye examination, including a dilated retinal examination at intervals recommended by their ophthalmologist.

Keeping blood sugar, blood pressure and cholesterol, under control can help reduce the risk of complications. If damage is detected treatment may include eye injections, laser therapy or surgery depending on its severity.

Diabetic eye disease can often be managed effectively when identified early. Regular retinal examinations remain important when a person can see clearly as changes may develop before symptoms appear.

By Dr Ashu Agarwal, Senior Consultant, Opthalmology, Indraprastha Apollo Hospital, Delhi