Itchy, red eyes in PM2.5 haze season: what can I do?

In PM2.5 haze season many people get itchy, stinging, red and watery eyes, because dust and smoke in the air land directly on the surface of the eye and irritate it. What you can do straight away is stop rubbing, wash your hands before touching your eyes, use a cool compress, skip contact lenses while your eyes are red, wear glasses outdoors, keep windows shut and run an air purifier at home, and check the air quality colour level before you go out. Do not choose eye drops on your own; ask a pharmacist or doctor. See a doctor if you have eye pain, changes in your vision, sensitivity to light or a lot of discharge.

Why do my eyes get itchy and red in PM2.5 season?

Your eyes are one of the few parts of the body that are open to the air all day. When the air is full of fine dust and smoke, the surface of the eye meets it before anything else.

Dust and smoke irritate the surface of the eye

The American Academy of Ophthalmology (AAO), the US association of eye doctors, describes stinging, burning, red eyes as the typical reaction to smoky air. Thailand's Pollution Control Department also lists eye irritation as one of the signs the general public should watch for once air quality reaches the level where it starts to affect health. Common complaints in haze season include itching, stinging, redness, watering and a gritty feeling, as if something is in the eye.

Eyes that are already dry are more sensitive

The AAO notes that people who already have dry eyes are more sensitive to smoke. In Thailand the haze often arrives in the cool, dry months, and many people spend the day in air-conditioned rooms with the windows closed, staring at screens and blinking less. All of this dries the surface of the eye and makes it easier to irritate.

Rubbing and unwashed hands

When your eyes itch, it is natural to rub them without thinking. The AAO warns that rubbing can scratch the eye and make itching worse. Hands that have touched handrails, phones and face masks all day can also carry more dirt to your eyes, so the irritation keeps coming back.

Contact lenses

Dust that gets into the eye can become trapped between the lens and the surface of the eye. That is why contact lens wearers often feel more discomfort in haze season than people who wear glasses or nothing at all.

My eyes are itchy and red during PM2.5 haze season. How should I look after them?

Start with simple steps that need no medicine: do not rub, wash your hands before touching your eyes, rinse your face and eyelids when you get home, and use a cool compress. Then cut down how much dust reaches your eyes, both outdoors and at home.

Do not rub your eyes

This matters most and is the hardest to do, because the more your eyes itch, the more you want to rub. When the itch starts, stop your hands and use a cool compress instead. If you tend to rub your eyes in your sleep, washing your face before bed and changing pillowcases often can cut down the dust around your eyes.

Wash your hands, face and eyelids

The AAO advises washing your hands often, not touching your eyes unless you have just washed your hands, and keeping bedding and towels clean. When you come home, wash your hands first, then gently rinse your face and eyelids with clean water to remove dust caught in your lashes and on the skin around your eyes. If you wear eye make-up, you may want to take it off earlier on high-haze days.

If dust or grit gets in your eye

The UK's NHS advises washing the eye with clean water that is not hot, whether from a tap, a shower or a bottle. Hold your eye open and let clean water run gently over the eyeball to wash the dust out. Do not touch or rub the eye, and avoid contact lenses and eye make-up until it feels normal again. If it is not getting better after 24 hours, the NHS advises getting medical help.

Use a cool compress

The AAO suggests placing a cool, damp cloth over your closed eyes a couple of times a day, and says lying down with a cold compress over your eyes is soothing. Use a fresh clean cloth each time and do not share it with others.

Can I wear contact lenses when the haze is bad?

If your eyes are red or irritated, leave your lenses out for now. The NHS advises not wearing contact lenses when you have a red eye, and the US CDC advises removing your lenses and contacting your eye care provider if your eyes feel uncomfortable.

On high-haze days

• Switch to glasses instead of contact lenses if you have a pair.
• If you need to wear lenses, wash your hands thoroughly with soap and water before handling them every time, as the CDC recommends.
• Take your lenses out when you get home, then rinse your face and eyelids.
• Care for your lenses and case as your eye care provider has advised, and keep your regular eye check-ups.

Signs not to wait on

The NHS says that if you wear contact lenses and your eye is red, you should get it checked promptly, especially if it is also painful. Do not keep wearing your lenses to see whether it settles.

How can I keep dust away from my eyes outdoors and at home?

The first thing that matters is letting less dust reach your eyes, through glasses, choosing when to go out, and managing the air at home.

Wear glasses when you go out

The AAO says close-fitting glasses or sunglasses provide at least some barrier against smoke, and wraparound goggles give more protection. A dust mask reduces how much you breathe in but does not protect your eyes, so use it together with glasses.

Check the air quality colour before going out

Thailand's Pollution Control Department reports air quality in five colour levels, each with advice. Use the colour to decide how long to stay outside and whether to move outdoor activities to another day.

The department advises older adults, young children and pregnant women to take extra care from lower levels than this. If your eyes are already irritated at orange, take it as a signal to cut your time outdoors. The AQI is not the dust concentration itself and is averaged over a set period; to read the numbers correctly, see How do you read PM2.5 and AQI figures?

Manage the air at home

• The AAO advises closing windows and staying indoors as much as possible when the air is smoky, especially if your eyes tend to be dry.
• An air purifier with a HEPA filter can help keep smoke and dust out of your home, according to the AAO.
• Air from an air conditioner or fan blowing straight at your face dries your eyes, so angle it away.
• When you are at a screen, blink on purpose and take regular breaks so dryness does not add to the irritation.

Can I just buy eye drops myself?

It is best not to choose eye drops on your own; ask a pharmacist or doctor before using any. Itchy, red eyes can have several causes, and different eye drops suit different causes.

Before you go to the pharmacy

• Tell the pharmacist what your symptoms are, how long you have had them, whether you wear contact lenses, and whether you take any regular medicines.
• Do not use someone else's eye drops.
• If your eyes do not get better after following the advice, go back to a doctor rather than switching products yourself.

As the AAO puts it, if these simple measures do not bring relief, ask an eye doctor for help.

When should I see a doctor about itchy, red eyes?

Most itchy, red eyes from haze can be looked after at home, but some signs should not wait. The NHS and the AAO list the following.

See a doctor or eye care provider

• Pain in or around your eye, or unusual tenderness
• Unusual sensitivity to light
• A lot of sticky discharge, or discharge that is yellow, green or brown
• A red eye while you wear contact lenses
• A fever or feeling unwell overall
• Symptoms that do not get better within a week of home care, or dust in the eye that is not better after 24 hours
• You are worried about your symptoms

Go to an emergency department straight away

• Changes in your vision, such as wavy lines, flashes or loss of vision
• Sensitivity to light together with a severe headache and feeling sick
• A very dark red eye
• Pupils that are different sizes
• An eye injury, something stuck in your eye, or a chemical splashed into it

The NHS advises not driving yourself in an emergency; ask someone to take you or call an ambulance.