AMSTERDAM — That air pollution is a primary antagonist to pulmonary health has been known for a long time, but the true extent of its detrimental effects may reach far beyond the lungs. Air pollutants infiltrate the bloodstream, damage multiple organ systems, and contribute significantly to global mortality.

Pulmonary experts and epidemiologists at European Respiratory Society (ERS) Congress 2025 discussed the well-documented dangers of outdoor air pollution and the often-overlooked hazards lurking within our own homes, from traditional cooking fuels to everyday cleaning products.

Air pollution is a multi-faceted global health crisis that demands immediate and comprehensive action, Kristie Ebi, PhD, an environmental epidemiologist and professor of global health and environmental and occupational health sciences at the University of Washington, Seattle, said at the Congress. “The literature has expanded significantly over the last several years, moving beyond impacts directly on the pulmonary system,” she said.

She explained that fine particulate matter, specifically PM2.5, is capable of crossing the lung-blood barrier, therefore entering the bloodstream and affecting a wide array of organ systems. This systemic invasion transforms what was once considered a purely respiratory issue into a cardiovascular, neurological, and systemic threat, she said.

According to data from the Institute for Health Metrics and Evaluation, air pollution is the second leading risk factor for illness and death, and the most vulnerable to it are children and older adults. Low-income countries, such as South Asia, Africa, and the Middle East, also bear the biggest burden.

The sources of air pollution are varied and geographically diverse. In regions like East and South Asia, coal combustion remains a significant contributor. In other parts of the world, oil, gas, and biofuels are the primary culprits.

In addition, a growing body of research, triggered by the increase of climate-driven wildfires, has shown that fire-related particulate matter is especially concerning. “Fire-related particulate matter is much more toxic than regular PM2.5,” Ebi said. For instance, in one study, researchers found that underestimating this specific risk could be off by as much as 93%.

The Hidden Dangers in Indian Kitchens

While outdoor pollution sources, such as traffic and industry often dominate public discourse, a significant portion of the global population is exposed to dangerously high levels of pollution within their own homes. Naresh Chandra Gupta, PhD, a professor at the University School of Environment Management in Delhi, India, presented a study on the effects of biomass fuel use in India, where around 41% of the population relies on biomass for cooking and heating, particularly in rural and marginalized communities, according to the India’s Centre for Science and Environment.

The traditional cookstoves, or chulhas, used in these homes are notoriously inefficient, converting a large portion of the fuel into smoke rather than heat, Gupta explained. This smoke contains a toxic cocktail of particulate matter (PM10, PM2.5, and PM1), black carbon (soot), hydrocarbons, and harmful gases like carbon monoxide, which have been associated with a wide range of disease, including respiratory infections and cancers. According to the World Health Organization, household air pollution alone was responsible for 3.8 million deaths, or 7.7% of the global mortality in 2018.

Gupta’s research documented the indoor air quality in homes using biomass vs those using cleaner liquefied petroleum gas (LPG). He found that homes using biomass had PM2.5 levels averaging over 700 μg/m³, with peaks exceeding 1900 during cooking hours, while in the household that used LPG levels were lower.

The health implications are especially severe on women because they are generally the ones who spend hours cooking in these conditions. Gupta’s study found a significantly higher prevalence of chronic cough, wheezing, and shortness of breath among women using biomass fuels. Pulmonary function tests revealed a much higher incidence of obstructive and restrictive patterns, with a pooled odds ratio indicating that biomass exposure increased the risk of developing Chronic Obstructive Pulmonary Disease (COPD) by 2.65 times. “The specific contribution of biomass fuel to declining lung function and respiratory diseases in women still remains under-investigated,” Gupta said, hinting that the true burden of disease is likely even higher.

The study also highlighted the important role of ventilation. Homes with poorly ventilated kitchens had exponentially higher pollutant concentrations and their inhabitants suffered from more severe respiratory symptoms.

Dirty Cleaning Products

Another source of indoor air pollution are cleaning products. Sara De Matteis, MD, MPH, PhD, a professor of occupational and environmental medicine at the University of Cagliari, Cagliari, Italy, said typical household products are a heavily underestimated hazard. “Cleaning products are in every house, in every building, and there has been a striking increase in their use in the last decades, particularly evident during the COVID-19 pandemic,” she said. This surge in use means a surge in exposure to a complex mixture of volatile organic compounds, acids, bases, solvents, disinfectants, and even ultrafine particles. And similarly to the Indian case, cleaning products too disproportionately affect women and children, she said.

These chemicals can easily become airborne, especially when used as sprays in poorly ventilated areas. De Matteis explained that these products can be potent respiratory irritants and sensitizers, capable of triggering asthma-like symptoms. A meta-analysis she presented revealed a 50% increased risk for such symptoms associated with exposure to cleaning products. The risk is not limited to professional cleaners but extends to the general population.

Presenting data from a large-scale UK Biobank study revealed that domestic cleaners have a 40% increased risk of developing COPD. “We were confident that this result was true because the huge sample size of UK Biobank allowed me to stratify the analysis among never-asthmatics and never-smokers,” she said. This stratification allowed her to rule out common confounders. Other studies have found that cleaning products are also associated with asthma, chronic cough, inducible laryngeal obstruction, and chronic bronchitis.

The danger not only is direct but also can be generational. A multi-center study found that maternal exposure to cleaning products around the time of conception and during pregnancy was linked to an increased risk for asthma in their children.

One big challenge De Matteis identified is the lack of transparency and regulation around product labeling. Product formulations are constantly changing, and manufacturers are often not required to disclose all ingredients, especially those present at concentrations < 1%, she explained. This makes it difficult for consumers and researchers to assess the real risks.

A Call for Integrated Solutions

The experts called for comprehensive strategies that simultaneously address various pollution sources and acknowledge their deep connections to public health and the global climate.

For household air pollution in developing nations such as India, the answer lies in a transition to cleaner fuels and more efficient, properly ventilated cooking technologies, said Gupta. Government initiatives, like India’s Ujjala Yojana program providing free LPG connections, are ongoing.

While for the hazards posed by cleaning products, De Matteis advocates for greater consumer awareness, improved product labeling, and the use of safer, greener alternatives, such as vinegar and biocarb.

To address outdoor air pollution, Ebi said, any action we take to mitigate climate change — reducing our reliance on fossil fuels, changing our consumption patterns — will have immediate and significant co-benefits for public health. “Reducing these sources of indoor and outdoor air pollution are part of what is considered mitigation to climate change,” she said. “The benefits for health of reducing these emissions will move forward on important agendas to help protect people throughout the world from exposure to air pollution.”

Ebi, Gupta, and De Matteis reported no relevant financial relationships.

Manuela Callari is a freelance science journalist specializing in human and planetary health. Her work has been published in The Medical Republic, Rare Disease Advisor, New Scientist, The Guardian, MIT Technology Review, and others.