The air you breathe daily could be triggering asthma without you knowing

Step outside on a winter morning in Delhi, and the haze feels almost familiar. It sits quietly in the background, yet inside the body, it is anything but quiet. Tiny particles travel deep into the lungs, settle there, and begin a slow chain reaction. Over time, that invisible exposure starts to show up as breathlessness, wheezing, or a cough that refuses to leave.As Dr Nimish Shah, Consultant Chest Physician, Jaslok Hospital & Research Centre, explains, “Air pollution has been a cause of worry not recently, but since many decades. It has only been increasing year on year which has brought it into highlight more so often.”So the question is simple, but important: can everyday air pollution really trigger asthma and breathing problems? The answer is yes, and the reasons are more layered than most realise.Air pollution is not a single substance. It is a mix of particles and gases that behave differently inside the body. The most dangerous among them are PM2.5 and PM10, along with gases like nitrogen dioxide and ozone.“The AQI or Air Quality Index has been used frequently as a marker to check levels of air pollution… It categorizes air quality into six levels—good to severe based on 8 major pollutants,” says Dr Shah.The smallest particles are the most harmful. Fine particles can slip past the body’s natural filters and reach the alveoli, the tiny air sacs where oxygen enters the blood. Ultra-fine particles go even further. They cross into the bloodstream and travel to other organs.These particles come from everyday sources: vehicle exhaust, construction dust, burning waste, even indoor cooking smoke. In cities, exposure is not occasional. It is constant.A study has linked long-term exposure to air pollution with reduced lung function and rising respiratory disease burden.The lungs are built to handle clean air, not toxic mixtures. When pollutants enter, the body reacts defensively. That reaction is what leads to symptoms.First comes irritation. The lining of the airways becomes inflamed. Then comes narrowing. Airways tighten, making it harder to breathe. Over time, repeated exposure keeps the lungs in a constant state of stress.This is why asthma flares up.Pollution does three things at once:Children are especially vulnerable. Their lungs are still developing, so damage during these years can have long-term effects.According to data and health assessments by NIH, high AQI periods often see a spike in respiratory outpatient visits.Globally, the World Health Organization (WHO) has classified outdoor air pollution as a Group 1 carcinogen, meaning it is proven to cause cancer. Breathing issues are only the beginning. Pollution does not stay confined to the lungs.“These pollutants tend to enter the circulatory system… resulting in increase in blood pressure… irregular heartbeats and hence result in strokes and heart attacks,” explains Dr Shah.Here is what often goes unnoticed:Even more concerning is the link with oxidative stress. This process damages cells and increases the risk of cancer over time.These are not rare outcomes. They are becoming routine in high-pollution zones.Cleaning the air is a large-scale effort, but reducing exposure at an individual level still makes a difference.Governments have already taken steps. Programmes like the National Clean Air Programme (NCAP), BS-VI emission norms, and real-time air monitoring aim to control pollution at the source.But daily habits matter too.Small changes that help:Dr Shah also stresses the role of awareness: “It is important to take note of the adverse effects of air pollution and alongside the government make a conscious effort to reduce the same.”For vulnerable groups, including children, the elderly, and those with asthma, these steps are not optional. They are necessary.Medical experts consultedThis article includes expert inputs shared with TOI Health by:Dr Nimish Shah, Consultant Chest Physician, Jaslok Hospital & Research Centre.Inputs were used to explain how daily exposure to air pollution can quietly trigger asthma and breathing problems, and why understanding these risks is essential for protecting lung health.