One morning, the teacher started the class with a special introduction.

“Good morning, class. I have something very important to talk to you today. You already know what food allergies (过敏) are, right? If we have a food allergy, we can become seriously ill when eating a certain kind of food. Next week we will have a new student called James joining our class. He is allergic to tree nuts, peanuts, sesame, egg and garlic. Just a tiny amount of any of those things would make him very ill—possibly so ill that he would need to go to hospital. James carries EpiPens, which can help him if he has an allergic reaction, but we hope he will never need to use them.

So please keep in mind that firstly, try not to bring in too many of the following things in your lunchboxes: loose nuts, peanut butter, sesame oil, egg mayonnaise, and any other foods that contain the things James is allergic to. Secondly, I’d like everyone to avoid sharing food at lunchtime. And thirdly, I need you all to be very careful to wash your hands after eating. If you bring special food to share for celebrations or birthdays, please make sure that it does not contain any of the things that are a problem for James to eat.

I’m sure you’ll all do a wonderful job of welcoming James to our class. Does anyone have any questions? No? Well, let’s get on with our maths then.

Doctors in hospital emergency rooms often see accidental poisonings. A frightened parent arrives with a child who swallowed a cleaning liquid. Or perhaps the harmful substance is a medicine. Or it might be a chemical product meant to kill insects. These are common causes of accidental poisoning.

In cases like this, seek medical help as soon as possible. Save the container of whatever caused the poisoning. And look on the container for information about anything that stops the effects of the poison. Save anything expelled from the mouth of the victim. That way, doctors can examine it.

In the past, some people forced poisoning victims to empty the stomach. They need a liquid syrup of ipecac(催呕剂) to do this. But an organization of children’s doctors no longer advises parents to keep syrup of ipecac. The American Academy of Pediatrics says some poisons can cause additional damage when they come back up the throat.

Millions of people know a way to save a person who is choking on something trapped in the throat. The method is commonly known as the Heimlich Manoeuvre or abdominal thrusts(腹部按压), which you can do by getting directly behind a sitting or standing person. Put your arms around the victim’s waist. Close one hand to form a ball. Place it over the upper part of the stomach below the ribs. Place the other hand on top. Then push forcefully inward and upward. Repeat the abdominal thrusts until the object is expelled from the mouth. For someone who is pregnant or very fat, place your hands a little higher than with normal abdominal thrusts.

Red Cross experts say taking these steps can save many lives. But they also warn that abdominal thrusts are not for people who have almost drowned. They say the use of the method could delay other ways to re-start breathing in the victim. Abdominal thrust should be used only in cases where a near-drowning victim is choking on an object.

To learn more about first aid, ask a hospital or organization like a Red Cross or Red Crescent Society for information. There may be training classes offered in your area. If you know first aid methods, you can be calmer and more helpful in case of emergency.

There are some sounds most of us acknowledge are annoying — the crunching of crisps, the noise of the air conditioning or a screaming baby. These noises, for many people, act as a mere inconvenience that can distract us from the task at hand. However, there are some among us who have a much more severe response to these noises. The question we ask today is: Has a noise ever made you feel so angry that you could explode with rage? If the answer is yes, you may be suffering from misophonia.

The word “misophonia” literally means “a hatred of sound” and is sometimes called Selective Sound Sensitivity Syndrome. There are some experts who doubt the existence of the condition. However, for those who claim to suffer from it, the experience can be traumatic. Certain sounds cause intense emotional or psychological responses that may seem over the top compared with a non-sufferer’s complaints.

The sound of a loved one chewing their food could trigger a sufferer’s anxiety levels, or cause them to panic. It may even activate their fight-or-flight reaction, making them want to flee. In extreme cases, that feeling of panic may result in extreme anger and end up with sufferers going crazy. Also, these conditions can lead to social isolation and the sufferers may feel cut off, according to James Cartreine, a clinical psychiatrist.

Sadly, there’s no known cure. However, tinnitus (耳鸣) retraining therapy, which helps people tolerate noises, may aid sufferers, while cognitive behavioural therapy and counselling could also help people manage the condition. Sufferers use coping strategies that include avoiding places with lots of noises, like restaurants, or moving away when they feel like hitting someone due to their breathing.

So, the next time you see someone fly into a rage because of a sound that is driving them crazy, it may be due to a difficult condition they are trying to manage, and not just because they hate a certain sound.