When a disaster strikes, people’s immediate concerns revolve around survival, securing shelter, finding food, and ensuring the safety of their loved ones. However, even after the initial danger subsides, a hidden threat lingers in the environment: smoke, dust, toxic gases, mould, and infectious particles that can silently harm the lungs. For instance, when the earthquake hit Türkiye in 2023 and when floodwaters inundated Valencia in October 2024, images of widespread devastation captured global attention. Yet, one aspect of these disasters went largely unphotographed: the weeks that followed. During this time, fallen debris and dust began to jeopardise health, while mould proliferated in water-damaged homes, leading to allergies and exacerbating respiratory issues for those with asthma and related conditions.
Disasters vary enormously in appearance, but very little is known about how they injure the lung. In almost every event, inhaled particles and gases trigger oxidative stress, a form of chemical damage within the airway lining. The lung’s protective barrier weakens, inflammation sets in, and with repeated exposure, the airways thicken and scar; in the worst cases, this leads to cancer. The main culprit is particulate matter, particularly its smallest fractions. PM2.5, particles under 2.5 micrometres wide (for comparison, a single strand of human hair has a width of about 50-70 micrometres), travel deep into the lung. Ultrafine particles like PM1, smaller than a tenth of a micrometre, go even further, passing into the bloodstream and reaching other organs. With inhaled pollution, size matters more than anything else.
Every year, hundreds of thousands of tonnes of sand from the Sahara Desert travel across the Atlantic Ocean and ultimately settle on the east coast of the United States. These ultrafine dust particles are so minuscule that they can penetrate blood vessels and impact various internal organs. In a related context, the wildfires that occur almost annually on the West Coast of the U.S. and in northern Canada contribute significantly to air quality issues. Smoke generated by these fires can drift far beyond the burning areas, exposing entire communities to harmful fine particles. These smoke particles contain a wide range of particulate matter, some big, and some very tiny, commonly referred to as PM0.1, which can be 500 to 700 times smaller than the width of a human hair. Wildfire smoke poses serious health risks, particularly for individuals suffering from asthma and chronic obstructive pulmonary disease (COPD), while also increasing the likelihood of bronchitis, pneumonia, and other infections. Vulnerable populations, such as children, the elderly, pregnant women, and individuals with pre-existing cardio-respiratory diseases, are particularly susceptible to these health impacts.
Climate change is having a significant impact on respiratory health, especially during heatwaves, when high temperatures stress the body and elevate ozone and other air pollutants. These conditions lead to increased pollen levels, which can worsen allergies and asthma. Research shows a correlation between extreme heat and an uptick in asthma attacks, hospitalisations for chronic obstructive pulmonary disease (COPD), and respiratory-related deaths. Children, older adults, individuals with chronic lung diseases, outdoor workers, and families living in poorly ventilated homes are particularly at risk. In addition to heatwaves, droughts and dust storms pose further threats to respiratory health. Dry soil and vegetation can produce airborne dust that irritates the airways and exacerbates conditions such as asthma and COPD. This dust can also carry harmful fungal spores and microorganisms, increasing the risk of chronic diseases, including interstitial lung disease. Flooding presents its own hazards, as damp environments encourage mould growth. Mould spores can trigger asthma and allergic reactions, while contaminated water sources, crowded living conditions, and poor sanitation can elevate the risk of respiratory infections. For individuals with pre-existing lung conditions, homes may feel unsafe even if the structure itself seems intact. Additionally, storms and thunderstorms introduce more risks. Strong winds can carry dust, debris, and pollutants, and damage to buildings can release mould and harmful chemicals. Thunderstorms can also trigger a phenomenon known as thunderstorm asthma, in which rain and wind break pollen into tiny particles that can penetrate deep into the airways, sometimes resulting in severe asthma attacks.
Earthquakes and volcanic eruptions expose people to a different mixture of hazards. Collapsed buildings release silica, asbestos and fine dust. Damaged gas lines can release carbon monoxide, while radon from the ground may increase long-term lung cancer risk. Volcanic ash contains sharp mineral particles, and volcanic gases can cause coughing, bronchitis, asthma attacks and acute respiratory distress. Rescue workers are often exposed to these substances while clearing debris or assisting survivors.
One further pattern runs through everything: a hurricane does not choose its victims, but a society can. Low-income and marginalised communities already have higher asthma rates, poorer housing, and fewer resources to prepare or recover. A patient who cannot afford a spare inhaler is at genuine risk when the pharmacy closes or floods. However, some people face these situations even more harshly. Firefighters and other first responders take the heaviest exposures, and those who fight wildfires are often the least well-protected of any group we studied. Breathing tests show that people with a history of smoke exposure have weaker lungs, a higher chance of developing asthma, and worse outcomes if they catch infections, such as influenza or COVID-19. However, most of this information comes from single tests rather than long-term studies, an area that needs more research.
We believe respiratory protection must be included in every stage of disaster planning. Authorities should monitor air quality, issue early warnings, and provide clean-air and cooling shelters. While none of this is inevitable, precautions are important. Our key message: A disaster does not end when the flames are extinguished or the floodwater disappears. Its respiratory danger may remain in smoke, mould, dust and contaminated air long after the headlines have moved on.
