<br />SDG 3 Good health and well-being<br />SDG 7: Affordable and clean energy<br />SDG 9Industry, innovation and infrastructure<br />SDG 13 Climate action<br />Pollution Components in Exhaust from Gas Oil-Driven Buses <br />Dr. Malik Mustafa Mohammed<br />1. Introduction <br />Gas oil (diesel fuel)-powered buses are a major source of urban air pollution, emitting harmful pollutants that impact human health and the environment. This report identifies and analyses the key components of exhaust emissions from diesel buses, their formation mechanisms, and mitigation strategies. <br /><br />2. Major Pollutants in Diesel Exhaust <br />1. Particulate Matter (PM) <br /> - Components: Fine particles (PM2.5) and ultrafine particles, composed of soot (carbon), ash, and metallic compounds. <br /> - Formation: Incomplete combustion of fuel and lubricating oil. <br /> -Impact: Penetrates lungs, causing respiratory diseases (asthma, COPD) and cardiovascular issues. <br /><br />2. Nitrogen Oxides (NOx) <br /> - Components: Nitric oxide (NO) and nitrogen dioxide (NO₂). <br /> - Formation: High-temperature combustion in engines combines nitrogen and oxygen. <br /> - Impact: Contributes to smog, acid rain, and ozone formation; exacerbates asthma and lung conditions. <br /><br />3. Sulfur Dioxide (SO₂) <br /> - Source: Sulfur in gas oil oxidizes during combustion. <br /> -Impact: Causes acid rain, respiratory irritation, and damages ecosystems. <br /><br />4. Carbon Monoxide (CO) <br /> - Formation: Incomplete fuel combustion due to insufficient oxygen. <br /> - Impact Reduces oxygen transport in blood, leading to headaches, dizziness, and cardiovascular stress. <br />5. Hydrocarbons (HC) <br /> - Components: Unburned fuel and lubricating oil (e.g., benzene, formaldehyde). <br /> - Formation: Incomplete combustion and fuel evaporation. <br /> - impact: Reacts to form ozone (smog); some HCs are carcinogenic. <br />6. Greenhouse Gases (GHGs) <br /> - Components: Carbon dioxide (CO₂) and nitrous oxide (N₂O). <br /> - Impact: Drives climate change; CO₂ accounts for ~95% of bus exhaust GHG emissions. <br />3. Formation Mechanisms <br />- Combustion Process: Diesel engines operate at high compression ratios, leading to elevated temperatures that favor NOx formation. <br />- Fuel Composition: High sulfur content in gas oil increases SO₂ emissions. <br />- Engine Design: Older, poorly maintained engines produce more PM and CO due to inefficient combustion. <br /><br />4. Health and Environmental Impacts <br />- Human Health: <br /> - PM and NOx linked to 4.2 million premature deaths globally (WHO). <br /> - Diesel exhaust classified as carcinogenic (IARC). <br />- Environment: <br /> - Acid rain from SO₂ and NOx harms soil, water, and vegetation. <br /> - PM contributes to haze and black carbon deposition, accelerating ice melt. <br />5. Regulatory Standards <br />- Emission Norms: Euro VI (EU), EPA Tier 4 (US), and Bharat Stage VI (India) mandate stringent PM and NOx limits. <br />- Fuel Quality: Ultra-low sulfur diesel (ULSD, ≤10–15 ppm sulfur) reduces SO₂ and enables emission control technologies. <br />6. Mitigation Strategies <br />1. Cleaner Fuels: <br /> - Transition to ULSD and renewable diesel (e.g., HVO). <br />2. Emission Control Technologies: <br /> - Diesel Particulate Filters (DPF): Trap 90%+ of PM. <br /> - Selective Catalytic Reduction (SCR): Reduces NOx via urea injection. <br />3. Engine Upgrades: <br /> - Retrofit older buses with EGR (Exhaust Gas Recirculation) systems. <br />4. Policy Measures: <br /> - Incentivize electric/hybrid buses and enforce regular emission testing. <br />5. Public Awareness**: Promote cleaner alternatives and sustainable transit. <br /><br />7. Challenges <br />- Cost: Retrofitting or replacing fleets requires significant investment. <br />- Fuel Quality: High-sulfur gas oil persists in some regions due to refining limitations. <br />- Compliance: Weak enforcement of emission standards in developing nations. <br />8. Conclusion <br />Diesel bus exhaust poses serious risks, but advancements in fuel quality, engine design, and emission control technologies offer viable solutions. Addressing this crisis requires coordinated efforts from governments, manufacturers, and urban planners to prioritize cleaner public transport systems. <br />References: WHO, EPA, European Environment Agency, and International Council on Clean Transportation (ICCT) reports. <br />This report emphasizes the importance of transitioning to low-emission buses and implementing stricter regulations to protect public health and ecosystems.<br />Al-Mustaqbal University The First University in Iraq<br /><br /><br />