Air pollution: An alarming threat to respiratory health

Air pollution is a silent yet relentless global health crisis, insidiously infiltrating the air we breathe and wreaking havoc on respiratory health. This pervasive threat, driven by a toxic cocktail of pollutants; particulate matter (PM2,5 and PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), carbon monoxide (CO), and volatile organic compounds (VOCs) stems from diverse sources such as vehicular exhaust, industrial emissions, fossil fuel combustion, and household activities such as cooking or using chemical cleaners.[1] Indoor air pollution, often overlooked, poses an equally formidable risk, fueled by inadequate ventilation, tobacco smoke, mold, and emissions from household products in tightly sealed, energy-efficient buildings.[2] The World Health Organization (WHO) estimates that annually air pollution claims approximately 7 million lives globally and about 2 million in India with respiratory and cardiovascular diseases as leading causes of premature mortality.[1] Fine PM2.5, capable of penetrating deep into the lungs, alveoli, and ground-level ozone, a potent respiratory irritant, are particularly insidious, exacerbating conditions such as allergies, asthma, and chronic lung diseases.[3] In regions like India, urban centers such as Delhi choke under a haze of smog from traffic, industrial activities, and agricultural burning, creating a public health emergency that disproportionately burdens vulnerable populations.[1,4] Globally, the impact of air pollution varies, shaped by regional differences in pollution sources, regulatory frameworks, and socioeconomic disparities. Low-income communities, often near industrial zones or high-traffic corridors, face heightened exposure, perpetuating health inequities.[1] Climate change further amplifies this crisis, with rising temperatures and extreme weather events such as wildfires and dust storms intensifying air quality challenges.[1,4] Air pollution’s assault on the respiratory system is multifaceted, triggering inflammation, oxidative stress, immune dysregulation, mucus hypersecretion, and ciliary dysfunction.[2,4] These mechanisms drive chronic damage, impairing lung function and exacerbating respiratory diseases. Vulnerable populations such as children with developing lungs, the elderly with diminished physiological reserves, and individuals with preexisting conditions bear the brunt of this toxic burden.[4] Allergic disorders, such as allergic rhinitis and eczema, arise from an overactive immune response to environmental allergens such as pollen, dust mites, or pet dander. Air pollutants, particularly PM2.5 and NO2, amplify allergen potency by altering protein structures, rendering them more immunogenic.[1,4] In urban environments, where vehicular emissions are rampant, pollutant-exposed pollen can fragment into sub-pollen particles, penetrating deeper into the respiratory tract and intensifying symptoms such as nasal congestion, sneezing, and ocular irritation.[4] In addition, parali burning, a common agricultural practice in states such as Punjab, Haryana, and Uttar Pradesh, releases harmful pollutants, including PM2.5, PM10, carbon monoxide, nitrogen oxides, and other toxic chemicals.[5] These pollutants from parali burning degrade air quality, travel long distances, and affect nearby cities. Moreover, the dense smog generated by parali burning significantly reduces visibility, leading to increased road accidents and disruptions in air and rail transport.[5] VOCs from paints, cleaning agents, and formaldehyde-emitting furnishings and mold growth in poorly ventilated spaces create a perfect storm for allergic sensitization. In energy-efficient homes, where airtight designs trap pollutants, residents face chronic exposure, leading to persistent symptoms and diminished quality of life. For millions, the simple act of breathing in their own homes becomes a daily struggle, underscoring the urgent need for improved indoor air quality management.[6] Asthma is profoundly aggravated by air pollution. Pollutants such as PM2.5, NO2, and O3 irritate the airways, precipitating acute exacerbations characterized by wheezing, shortness of breath, and persistent coughing.[2] Ground-level ozone, formed through photochemical reactions of vehicle and industrial emissions, is a notorious asthma trigger, particularly during warmer months when sunlight intensifies its formation.[4] Traffic-related air pollution is a significant culprit, with a 2020 study estimating a 50% increased asthma risk in children living near high-traffic zones.[7] In urban centers like Delhi, where NO2 levels frequently exceed safe limits, asthma-related emergency room visits surge during peak pollution seasons.[1] Indoor pollutants, such as tobacco smoke, VOCs, and PM from cooking or heating, exacerbate asthma in poorly ventilated environments, disproportionately affecting low-income households reliant on biomass fuels.[2] Air pollution, particularly PM2.5, plays a pivotal role in the development and exacerbation of Chronic Obstructive Pulmonary Disease (COPD). Chronic exposure to fine particulates induces alveolar inflammation, oxidative stress, and tissue remodeling, leading to scarring and diminished lung capacity.[2,4] PM2.5 triggers the release of pro-inflammatory cytokines, such as interleukin-6 and tumor necrosis factor-alpha, which exacerbate airway obstruction and impair gas exchange. In India, where air quality frequently exceeds WHO guidelines, COPD exhibits a high prevalence, driven by a dual burden of urban air pollution and rural biomass combustion.[8] Clinical manifestations, including persistent cough, dyspnea, and recurrent respiratory infections, significantly diminish quality of life, with air pollution linked to increased exacerbations, hospitalizations, and mortality. Globally, the WHO estimates that air pollution contributes to 3.2 million deaths annually, underscoring its role as a primary environmental risk factor for COPD.[6,8] Air pollution is a definitive risk factor for lung cancer, classified as a Group 1 carcinogen by the International Agency for Research on Cancer.[4] Fine PM2.5 and polycyclic aromatic hydrocarbons (PAHs) from combustion sources, such as vehicle exhaust and industrial emissions, drive carcinogenesis through DNA damage, oxidative stress, and chronic inflammation.[2] PM2.5 particles, small enough to lodge deep in the alveoli, initiate mutagenic processes, increasing the risk of adenocarcinoma, the most common lung cancer subtype in non-smokers.[4] PAHs, prevalent in diesel exhaust, form DNA adducts that disrupt cellular repair mechanisms, elevating cancer risk.[4] In India, air pollution contributes to an estimated 10% of lung cancer cases, with urban residents and occupational groups like truck drivers facing heightened exposure.[2,5] Chronic exposure to air pollutants, particularly PM2.5 and occupational dusts, is implicated in interstitial lung disease (ILD) progression through sustained inflammation and oxidative stress.[6,8] While the precise mechanisms remain under investigation, evidence suggests that pollutants trigger fibroblast activation, leading to excessive collagen deposition and lung fibrosis. In regions with heavy industrial activity, such as India’s coal-mining belts, ILD prevalence is rising, with workers facing disproportionate risks.[6] The impact of air pollution on respiratory health varies globally, shaped by regional differences in pollution sources, economic development, and regulatory frameworks. In high-income countries, stringent emission standards and cleaner energy adoption have reduced ambient pollution, yet indoor air quality remains a concern in urban households.[6] Socioeconomic disparities further compound the crisis, with marginalized communities often located near industrial zones or highways facing disproportionate exposure. In the United States, Black and Hispanic populations are 1.5 times more likely to live in areas with poor air quality, highlighting environmental injustice.[9] Addressing these disparities requires equitable policies that prioritize vulnerable populations. Air pollution’s devastating impact on respiratory health, spanning allergies, asthma, COPD, lung cancer, and ILDs, demands urgent, multifaceted action. The global nature of this crisis, exacerbated by climate change and socioeconomic inequities, underscores the need for comprehensive strategies to protect public health. We need to combat to the issue of air pollution with renewed focus and determination such as, real-time air quality monitoring, exposure reduction, enhancing indoor air quality, protecting vulnerable populations, policy advocacy, urban greening initiatives, reducing personal emissions, promoting healthy lifestyles, medical interventions, exploring emerging therapies.[1-6] By integrating individual actions, community initiatives, and robust policy reforms, the respiratory health burden of air pollution can be significantly reduced. The fight against air pollution is not just an environmental imperative but a moral one, demanding collective resolve to ensure clean air for all. Every breath counts let’s make it a healthy one. LiFE (Lifestyle for Environment) program was launched by Prime Minister Narendra Modi on June 5, 2022, with the appeal to all citizens of India to follow a lifestyle which protects the environment and reduces pollution.[3] Doctors for Clean Air and Climate Action (DFCA) is an initiative of the doctors of India since 2018 and creating a lot of awareness regarding air pollution and climate change in the fraternity and community. The author is sincerely and actively involved in DFCA and running a movement called “VAYU MITRA” for involving schools, college children, and NGOs to participate in the drive against air pollution. The author is also involved with many other NGOs to combat air pollution with his personal suggestions like the presentation of plant saplings in place of flower bouquets, make plant ceremonies a part of every ceremony, such as birthdays, marriage anniversaries, and engagements increase the use of public transport, no smoking and become an advocate for no smoking campaign and take the advantage of Ujjwala Yojna. Menace of air pollution can be handled not only with the efforts of the government, but everybody must be involved for clean air movement. We can live without food for 3 weeks, we can live without water for 3 days, but we cannot live without air for more than 3 min, hence this is the need of the hour everyone should contribute for the promotion of clean air and prevention of air pollution.