It has been a long winter, filled with many viruses and cost-of-living pressures, on top of the usual mix of work, study, life admin and caring responsibilities.

Stress is an inevitable part of life. In short bursts, our stress response has evolved as a survival mechanism to help us be more alert in fight or flight situations.

But when stress is chronic, it weakens the immune system and makes us more vulnerable to illnesses such as the common cold, flu and COVID.

Stress makes it harder to fight off viruses

When the immune system starts to break down, a virus that would normally have been under control starts to flourish.

Once you begin to feel sick, the stress response rises, making it harder for the immune system to fight off the disease. You may be sick more often and for longer periods of time, without enough immune cells primed and ready to fight.

In the 1990s, American psychology professor Sheldon Cohen and his colleagues conducted a number of studies where healthy people were exposed to an upper respiratory infection, through drops of virus placed directly into their nose.

These participants were then quarantined in a hotel and monitored closely to determine who became ill.

One of the most important factors predicting who got sick was prolonged psychological stress.

Cortisol suppresses immunity

“Short-term stress” is stress that lasts for a period of minutes to hours, while “chronic stress” persists for several hours per day for weeks or months.

When faced with a perceived threat, psychological or physical, the hypothalamus region of the brain sets off an alarm system. This signals the release of a surge of hormones, including adrenaline and cortisol.

In a typical stress response, cortisol levels quickly increase when stress occurs, and then rapidly drop back to normal once the stress has subsided. In the short term, cortisol suppresses inflammation, to ensure the body has enough energy available to respond to an immediate threat.

But in the longer term, chronic stress can be harmful. A Harvard University study from 2022 showed that people suffering from psychological distress in the lead up to their COVID infection had a greater chance of experiencing long COVID. They classified this distress as depression, probable anxiety, perceived stress, worry about COVID and loneliness.

Those suffering distress had close to a 50% greater risk of long COVID compared to other participants. Cortisol has been shown to be high in the most severe cases of COVID.

Stress causes inflammation

Inflammation is a short-term reaction to an injury or infection. It is responsible for trafficking immune cells in your body so the right cells are present in the right locations at the right times and at the right levels.

The immune cells also store a memory of that threat to respond faster and more effectively the next time.

Initially, circulating immune cells detect and flock to the site of infection. Messenger proteins, known as pro-inflammatory cytokines, are released by immune cells, to signal the danger and recruit help, and our immune system responds to neutralise the threat.

During this response to the infection, if the immune system produces too much of these inflammatory chemicals, it can trigger symptoms such as nasal congestion and runny nose.

What about chronic stress?

Chronic stress causes persistently high cortisol secretion, which remains high even in the absence of an immediate stressor.

The immune system becomes desensitised and unresponsive to this cortisol suppression, increasing low-grade “silent” inflammation and the production of pro-inflammatory cytokines (the messenger proteins).

Immune cells become exhausted and start to malfunction. The body loses the ability to turn down the inflammatory response.

Over time, the immune system changes the way it responds by reprogramming to a “low surveillance mode”. The immune system misses early opportunities to destroy threats, and the process of recovery can take longer.

So how can you manage your stress?

We can actively strengthen our immunity and natural defences by managing our stress levels. Rather than letting stress build up, try to address it early and frequently by:

1) Getting enough sleep

Getting enough sleep reduces cortisol levels and inflammation. During sleep, the immune system releases cytokines, which help fight infections and inflammation.

2) Taking regular exercise

Exercising helps the lymphatic system (which balances bodily fluids as part of the immune system) circulate and allows immune cells to monitor for threats, while sweating flushes toxins. Physical activity also lowers stress hormone levels through the release of positive brain signals.

3) Eating a healthy diet

Ensuring your diet contains enough nutrients – such as the B vitamins, and the full breadth of minerals like magnesium, iron and zinc – during times of stress has a positive impact on overall stress levels. Staying hydrated helps the body to flush out toxins.

4) Socialising and practising meditation or mindfulness

These activities increase endorphins and serotonin, which improve mood and have anti-inflammatory effects. Breathing exercises and meditation stimulate the parasympathetic nervous system, which calms down our stress responses so we can “reset” and reduce cortisol levels.

Sathana Dushyanthen, Academic Specialist & Lecturer in Cancer Sciences & Digital Health| Superstar of STEM| Science Communicator, The University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Mulch containing asbestos has now been found at 41 locations in New South Wales, including Sydney parks, schools, hospitals, a supermarket and at least one regional site. Tests are under way at other sites.

As a precautionary measure, some parks have been cordoned off and some schools have closed temporarily. Fair Day – a large public event that traditionally marks the start of Mardi Gras – was cancelled after contaminated mulch was found at the site.

The New South Wales government has announced a new taskforce to help investigate how the asbestos ended up in the mulch.

Here’s what we know about the risk to public health of mulch contaminated with asbestos, including “friable” asbestos, which has been found in one site (Harmony Park in Surry Hills).

What are the health risks of asbestos?

Asbestos is a naturally occurring, heat-resistant fibre that was widely used in building materials from the 1940s to the 1980s. It can be found in either a bonded or friable form.

Bonded asbestos means the fibres are bound in a cement matrix. Asbestos sheeting that was used for walls, fences, roofs and eaves are examples of bonded asbestos. The fibres don’t escape this matrix unless the product is severely damaged or worn.

A lot of asbestos fragments from broken asbestos products are still considered bonded as the fibres are not released as they lay on the ground.

Friable asbestos, in contrast, can be easily crumbled by touch. It will include raw asbestos fibres and previously bonded products that have worn to the point that they crumble easily.

The risk of disease from asbestos exposure is due to the inhalation of fibres. It doesn’t matter if those fibres are from friable or bonded sources.

However, fibres can more easily become airborne, and therefore inhalable, if the asbestos is friable. This means there is more of a risk of exposure if you are disturbing friable asbestos than if you disturb fragments of bonded asbestos.

Who is most at risk from asbestos exposure?

The most important factor for disease risk is exposure – you actually have to inhale fibres to be at risk of disease.

Just being in the vicinity of asbestos, or material containing asbestos, does not put you at risk of asbestos-related disease.

For those who accessed the contaminated areas, the level of exposure will depend on disturbing the asbestos and how many fibres become airborne due to that disturbance.

However, if you have been exposed to, and inhaled, asbestos fibres it does not mean you will get an asbestos-related disease. Exposure levels from the sites across Sydney will be low and the chance of disease is highly unlikely.

The evidence for disease risk from ingestion remains highly uncertain, although you are not likely to ingest sufficient fibres from the air, or even the hand to mouth activities that may occur with playing in contaminated mulch, for this to be a concern.

The risk of disease from exposure depends on the intensity, frequency and duration of that exposure. That is, the more you are exposed to asbestos, the greater the risk of disease.

Most asbestos-related disease has occurred in people who work with raw asbestos (for example, asbestos miners) or asbestos-containing products (such as building tradespeople). This has been a tragedy and fortunately asbestos is now banned.

There have been cases of asbestos-related disease, most notably mesothelioma – a cancer of the lining of the lung (mostly) or peritoneum – from non-occupational exposures. This has included people who have undertaken DIY home renovations and may have only had short-term exposures. The level of exposure in these cases is not known and it is also impossible to determine if those activities have been the only exposure.

There is no known safe level of exposure – but this does not mean that one fibre will kill. Asbestos needs to be treated with caution.

As far as we are aware, there have been no cases of mesothelioma, or other asbestos-related disease, that have been caused by exposure from contaminated soils or mulch.

Has asbestos been found in mulch before?

Asbestos contamination of mulch is, unfortunately, not new. Environmental and health agencies have dealt with these situations in the past. All jurisdictions have strict regulations about removing asbestos products from the green waste stream but, as is happening in Sydney now, this does not always happen.

What if I’ve been near contaminated mulch?

Exposure from mulch contamination is generally much lower than from current renovation or construction activities and will be many orders of magnitude lower than past occupational exposures.

Unlike activities such as demolition, construction and mining, the generation of airborne fibres from asbestos fragments in mulch will be very low. The asbestos contamination will be sparsely spread throughout the mulch and it is unlikely there will be sufficient disturbance to generate large quantities of airborne fibres.

Despite the low chance of exposure, if you’re near contaminated mulch, do not disturb it.

If, by chance, you have had an exposure, or think you have had an exposure, it’s highly unlikely you will develop an asbestos-related disease in the future. If you’re worried, the Asbestos Safety and Eradication Agency is a good source of information.

Peter Franklin, Associate Professor and Director, Occupational Respiratory Epidemiology, The University of Western Australia

This article is republished from The Conversation under a Creative Commons license. Read the original article.