Dr Vijay Garg
1. Why Road Dust Matters for Air Quality
Major Contributor to PM Pollution: In many Indian cities, “road dust” is not a negligible part of particulate pollution — it is a major source. For example, in Delhi, road dust has been identified by studies (including IIT-Kanpur) as a leading contributor to PM2.5 and PM10.
Varied Origins: Road dust is generated from many sources — construction materials (like gravel and concrete), road surface degradation, tire wear, and the resuspension of settled dust when vehicles pass.
Resuspension: Dust that has settled on roads doesn’t stay put. When vehicles move, especially at higher speeds or on poorly maintained roads, that dust is kicked up again — contributing repeatedly to airborne particulate matter.
2. Where Does the Dust Settle Physically?
When we talk about “where road dust settles,” we can think about both on-road accumulation and how it contributes to ambient (airborne) pollution:
a) On Road Surfaces and Shoulders
Unpaved Shoulders: In many Indian cities, even if roads are paved, the shoulders (edges) may not be. These unpaved sections accumulate a lot of soil and silt, which then contributes heavily to dust.
Poor Road Maintenance: Damaged or deteriorated roads (cracks, potholes) trap more loose particles. Over time, silt builds up on these surfaces, making them sources of resuspension.
Construction Sites: Debris from nearby construction (gravel, earth) adds to the dust load on adjacent roads.
b) In the Air (Ambient Environment)
Resuspended into the Air: As mentioned, traffic disturbs the settled dust, causing it to go airborne. This contributes significantly to PM10, and even to PM2.5 in many cases.
Local In Situ Dust: Especially in places like Delhi, much of the dust is “in situ” — meaning it’s not just being blown in from far-off deserts, but is coming from the city itself (roads, construction, road shoulders).
Deposition on Nearby Surfaces: Some of the dust eventually re-settles on nearby surfaces (buildings, vegetation, pavements), but because of constant traffic, a dynamic equilibrium often exists — dust lifts, settles, re-lifts.
3. Health and Environmental Impacts
Respiratory Risks: PM10 and PM2.5 (particulate matter) from road dust can penetrate deep into lungs, exacerbate asthma, bronchitis, and other respiratory diseases.
Urban Heat & Visibility: Dust can also affect local micro-climates (by reducing albedo) and visibility (smog), especially when combined with other pollutants.
4. India’s Efforts to Address Road Dust
Efforts to mitigate road dust are being scaled up, but challenges remain:
1. Mechanical Sweeping and Sprinkling
Municipal bodies are increasingly using mechanical/e-powered sweepers to clean road surfaces.
Sprinklers or water mist systems are also being used to suppress dust. For instance, in Mumbai, BMC (Brihanmumbai Municipal Corporation) has proposed vehicles with misting equipment to settle road dust.
2. Paving and Better Road Design
A major strategy is to pave unpaved shoulders and improve road surfaces so that dust resuspension is reduced.
In the Delhi-NCR region, agencies (CAQM, CSIR-CRRI, SPA) are collaborating to redevelop roads with a focus on paving + greening.
Better road cross-sections, design, and maintenance practices are being integrated to minimize dust generation.
3. Greening / Vegetation Barriers
Planting trees, grasses, vertical green walls, and other vegetation along road edges helps trap dust and acts as a barrier.
Green infrastructure is being increasingly recognized in urban planning as a dust-suppression tool.
4. Regulating Construction
Use of dust suppressants at construction sites to reduce wind erosion.
Policies to ensure vehicles leaving construction sites are cleaned (e.g., wheel wash) to minimize carrying dust onto roads.
5. Institutional Frameworks
The tripartite MoU (CAQM, CRRI, SPA) mentioned above includes a Project Monitoring Cell (PMC) to ensure the dust-control strategies are implemented and tracked.
Under the National Clean Air Programme (NCAP), many cities are mandated to take up these dust control measures.
5. Challenges / Gaps That Remain
Water Usage: Wetting roads (with sprinklers or mist) is effective to suppress dust, but it consumes a lot of water — a significant issue, especially in water-stressed cities.
Maintenance: Even after paving, roads need regular maintenance. Poor road quality (cracks, potholes) over time reintroduces dust.
Resource Constraints: Not all municipal bodies may have the budget or capacity to deploy mechanical sweepers, misting vehicles, or greening at scale.
Behavioral and Design: Some roads are poorly designed (e.g., narrow shoulders, no vegetation), making dust control difficult.
Monitoring & Accountability: Implementing policies is one thing, but sustained, data-driven monitoring (like using GIS systems) is needed to ensure that road redesign / dust control is effective.
6. Case Examples
Mumbai: NEERI (National Environmental Engineering Research Institute) found that road dust makes up 71% of the PM emission load in the city.
Kolkata: A recent TERI (The Energy and Resources Institute) study found road dust accounts for ~35% of PM10 and ~16% of PM2.5 in the city — more than vehicle emissions in some cases.
Punjab (Cities like Ludhiana, Jalandhar): According to PPCB (Punjab Pollution Control Board) findings, road dust is a major contributor. To counter this, they propose paving, vacuum cleaning, and mechanical sweeping.
7. Why “Settling” Road Dust Is Key to Cleaning the Air
Reducing airborne dust (PM) from roads is not just about preventing emissions, but also about preventing resuspension of already-deposited dust.
If dust is allowed to accumulate unchecked on road surfaces, every vehicle passing becomes a “dust stirrer,” continuously re-polluting the air.
Effective strategies need to both prevent dust accumulation (through better design, paving, green barriers) and manage existing dust (through cleaning, sprinkling).
8. Conclusion
Road dust is a critical, yet sometimes underappreciated source of particulate pollution in Indian cities.
It doesn’t just originate — it resettles, re-suspends, and keeps contributing to ambient PM levels.
India’s efforts to “make the dust settle” involve engineering (paving, road redesign), nature-based solutions (greening), and active maintenance (sweepers, sprinklers).
However, water use, funding, and consistent policy implementation remain big challenges.
If these efforts scale successfully, controlling road dust could make a significant dent in India’s urban air pollution problem.
Dr Vijay Garg Retired Principal Educational columnist Eminent Educationist street kour Chand MHR Malout Punjab |
