Water and Air Pollution

Air pollution is the presence in the atmosphere of harmful substances (gases, particles, biological matter) in amounts that damage human health, living things, materials or climate. Main pollutants: particulate matter (PM10, PM2.5), carbon monoxide (CO), sulphur dioxide (SO₂), nitrogen oxides (NOₓ), ground-level ozone (O₃), hydrocarbons/VOCs and lead.

Causes (sources)

Natural sources: volcanic eruption, forest fires, dust storms, pollen, sea salt.

Man-made sources:

1. Vehicles – burning of petrol and diesel gives CO, NOₓ, hydrocarbons and PM; old, poorly maintained vehicles are the worst.
2. Industries and power plants – cement, brick kilns, thermal plants release SO₂, NOₓ and dust.
3. Burning of fossil fuels and biomass – coal, firewood, dung and agricultural residue.
4. Construction and road dust – unpaved and dug-up roads, building works.
5. Open burning of waste – plastics release dioxins and toxic smoke.
6. Agriculture – ammonia from fertilisers, methane from livestock and rice fields, pesticide spraying.
7. Indoor sources – cooking with firewood and kerosene, smoking.

Effects

On human health

• Respiratory diseases: asthma, bronchitis, COPD, pneumonia, lung cancer.
• Heart disease and stroke (PM2.5 enters blood).
• CO reduces oxygen carrying capacity of blood; lead harms the brain of children.
• Eye irritation, headache, reduced life expectancy.

On environment

• Acid rain from SO₂ and NOₓ damages crops, forests, lakes and buildings.
• Global warming and climate change from CO₂, CH₄, black carbon.
• Ozone layer depletion by CFCs.
• Smog and reduced visibility, affecting flights and tourism.
• Damage to plants (reduced photosynthesis) and to monuments and metal structures.

Economic – medical costs, lost working days, lower tourism.

Mitigation measures

1. Vehicle control – emission testing and green stickers, phasing out old vehicles, better fuel quality (Euro standards), promoting electric vehicles and public transport.
2. Industrial control – filters, electrostatic precipitators, scrubbers, tall stacks, cleaner brick kiln technology (zig-zag kilns).
3. Clean energy – hydropower, solar, wind, biogas, LPG/electric cooking instead of firewood.
4. Dust control – paving roads, covering construction sites, water sprinkling, timely completion of road works.
5. Waste management – ban open burning, recycling, composting, sanitary landfill.
6. Greenery – tree plantation along roads and green belts.
7. Monitoring and law – air quality monitoring stations, National Ambient Air Quality Standards, strict enforcement.
8. Awareness – masks during high pollution, public information on AQI, behaviour change.

The fecal-oral route is the pathway by which disease-causing organisms (pathogens) present in the faeces of an infected person or animal enter the mouth of another person and cause infection. The pathogens are bacteria, viruses, protozoa and worm eggs.

Diseases spread this way: diarrhoea, cholera, typhoid, dysentery, hepatitis A and E, polio, giardiasis, amoebiasis, roundworm and hookworm infection. Diarrhoeal diseases are still a major cause of child illness in Nepal, especially in the monsoon.

Transmission route (F-diagram)

Pathogens travel from faeces to a new host through five "F"s:

             +--> Fluids (water) ------+
             |                         |
             +--> Fingers (hands) -----+
 FAECES -----+                         +--> FOOD --> MOUTH
             +--> Flies ---------------+       (new host)
             |                         |
             +--> Fields (soil, crops)-+

1. Fluids – drinking water polluted by sewage, open defecation near sources or leaking pipes.
2. Fingers – unwashed hands after toilet use or cleaning a child.
3. Flies – flies sit on faeces, then on food.
4. Fields – open defecation and use of raw night soil on fields; vegetables and soil get contaminated; children play on soil.
5. Food – contaminated by any of the above, or by unclean utensils and poor cooking.

Preventive measures

Barriers are put at two levels:

Primary barriers (stop faeces reaching the environment)

• Safe excreta disposal: use of sanitary toilets (pit latrine, pour-flush, septic tank); end open defecation (Nepal declared itself Open Defecation Free in 2019).
• Safe disposal of children's faeces.
• Hand washing with soap after defecation.

Secondary barriers (stop pathogens reaching the mouth)

• Safe drinking water – protect sources, boil, filter, chlorinate (e.g. Piyush), or SODIS.
• Hand washing with soap before cooking and eating.
• Food hygiene – wash fruits and vegetables, cook properly, eat hot food, cover food, clean utensils.
• Fly control – cover food and toilets, manage solid waste, keep surroundings clean.
• Proper sewage and waste water treatment; separate water supply and sewer lines.

Other measures

• Health and hygiene education in schools and communities.
• Vaccination (polio, typhoid, hepatitis A, rotavirus).
• Oral rehydration solution (ORS) and zinc for treatment of diarrhoea to prevent deaths.
• Regular deworming of children.

Breaking the route at the source (toilets + hand washing + safe water) gives the largest health benefit.

Environmental sanitation is the control of all those factors in the physical environment that harm, or may harm, human health and well-being. In practice it means safe disposal of human excreta, management of solid waste and waste water, safe water supply, food hygiene, vector control and clean housing, so that disease transmission is cut.

Components of environmental sanitation

1. Excreta disposal – sanitary toilets (pit latrine, VIP latrine, pour-flush, septic tank), sewerage.
2. Safe water supply – protected sources, treatment and safe storage.
3. Solid waste management – collection, segregation, recycling, composting and sanitary landfill.
4. Waste water (sullage) and drainage – soak pits, drains, treatment plants; no stagnant water.
5. Food sanitation – hygienic handling, storage and cooking.
6. Vector and rodent control – control of flies, mosquitoes, rats.
7. Housing and personal hygiene – ventilation, clean kitchens, hand washing.
8. Control of air and noise pollution.

Importance: prevents diarrhoea, cholera, typhoid, hepatitis, worm infections and vector-borne diseases; lowers child mortality; improves dignity (especially for women), school attendance and productivity; and protects water sources. Nepal's national sanitation campaign led to the ODF declaration in 2019 and now focuses on "total sanitation".

Pathways of fecal-oral infection transmission

Pathogens in faeces of an infected person reach a new person's mouth by the F-diagram routes:

             +--> Fluids (water) ------+
             +--> Fingers -------------+
 FAECES -----+--> Flies ---------------+--> FOOD --> MOUTH
             +--> Fields/soil ---------+       (new host)

1. Fluids – water sources contaminated by sewage, open defecation or leaking pipes; drinking it untreated.
2. Fingers – hands not washed after defecation or handling a baby; hands then touch food or mouth.
3. Flies – carry pathogens from open faeces and waste to food.
4. Fields – open defecation and raw excreta used as manure; contaminated soil and vegetables; children playing on soil.
5. Food – the final vehicle when contaminated by water, hands, flies or soil.

Diseases: cholera, typhoid, diarrhoea, dysentery, hepatitis A/E, polio, worms.

Barriers: toilets and safe excreta disposal (primary barrier); safe water, hand washing with soap, food hygiene and fly control (secondary barriers); supported by health education and vaccination.

Acid rain is rain, snow, fog or dust that is more acidic than normal, with pH below about 5.6. (Normal rain is slightly acidic, pH ≈ 5.6, because of dissolved CO₂.) It forms when sulphur dioxide and nitrogen oxides in the air react with water vapour to form sulphuric and nitric acids.

Causes

• Sulphur dioxide (SO₂) – from burning coal and oil in thermal power plants, industries, brick kilns, smelting of ores.
• Nitrogen oxides (NOₓ) – from vehicle exhaust, power plants and high-temperature combustion.
• Natural sources – volcanoes, lightning, decaying vegetation (smaller share).

Formation (simplified):

• SO₂ + H₂O + O₂ → H₂SO₄ (sulphuric acid)
• NOₓ + H₂O + O₂ → HNO₃ (nitric acid)

These acids fall as wet deposition (rain, snow) or dry deposition (acidic gases and particles), sometimes hundreds of kilometres away from the source.

Impacts (consequences)

1. Aquatic life – lakes and rivers become acidic; fish eggs and insects die; aluminium released from soil is toxic to fish.
2. Forests and crops – leaves damaged, nutrients (Ca, Mg) washed out of soil, trees weakened (e.g. forest dieback in Europe).
3. Soil – loss of fertility and of useful microbes.
4. Buildings and monuments – marble and limestone corrode (e.g. Taj Mahal yellowing; risk to stone temples); metals rust faster.
5. Human health – the SO₂ and NOₓ particles that cause acid rain also cause asthma and bronchitis; acidic water can leach lead and copper from pipes.

Control: low-sulphur fuels, flue gas desulphurisation (scrubbers), catalytic converters in vehicles, more renewable energy, and liming of acidified lakes.

Water pollution is any physical, chemical or biological change in the quality of water that makes it harmful to people and living organisms or unfit for its intended use (drinking, irrigation, industry, recreation).

Major sources

• Point sources – come from one identifiable place: sewage outfalls, industrial effluent pipes, hospital waste water.
• Non-point sources – spread over a large area: runoff from farms, urban streets, landfills and open defecation areas.

Causes

1. Domestic sewage discharged untreated into rivers (e.g. Bagmati in Kathmandu).
2. Industrial effluent – tanneries, dyeing, distilleries, paper mills release chemicals and heavy metals.
3. Agricultural runoff – fertilisers (nitrate, phosphate) and pesticides.
4. Solid waste dumping on river banks.
5. Open defecation and leaking septic tanks contaminating groundwater.
6. Natural sources – arsenic, iron and manganese in groundwater (Terai), sediments from landslides.
7. Oil spills, mining and sand extraction.
8. Thermal pollution – hot water from industries.

Impacts

• Health – water-borne diseases: cholera, typhoid, diarrhoea, hepatitis; arsenicosis from arsenic; blue-baby syndrome from nitrate.
• Aquatic ecosystem – organic matter consumes dissolved oxygen, fish die; eutrophication (algal bloom) from nutrients.
• Biomagnification of toxic substances (mercury, DDT) along the food chain.
• Economic – higher water treatment cost, loss of fisheries and tourism.
• Agriculture – polluted irrigation water harms crops and soil.
• Social and cultural – holy rivers and ghats lose their value; foul smell and nuisance in cities.

Control: sewage treatment, effluent standards for industries, safe sanitation, controlled use of agro-chemicals and protection of water sources.

Kathmandu valley often records PM2.5 levels many times above the WHO guideline, especially in winter and spring.

Major sources of air pollution in Kathmandu valley

1. Vehicles – the fastest-growing source; old diesel buses, trucks and the large number of motorcycles emit PM, CO, NOₓ and hydrocarbons; traffic jams increase emissions.
2. Road and construction dust – unpaved, dug-up roads (drinking water pipe and road widening works), building construction and open transport of sand.
3. Brick kilns – mainly in Bhaktapur and Lalitpur, burning coal and biomass in the dry season.
4. Open burning of waste – plastics and garbage burnt in streets.
5. Industries – cement, small factories, diesel generators.
6. Household fuel – firewood, kerosene and LPG in some homes.
7. Forest fires and trans-boundary pollution – smoke from fires in Nepal and haze from the Indo-Gangetic plain in spring.

Why topography worsens air quality

1. Bowl-shaped valley – Kathmandu is surrounded by hills (Shivapuri, Phulchowki, Chandragiri, Nagarjun) rising 700–1,500 m above the valley floor. Air cannot move out easily and pollutants are trapped.
2. Temperature inversion – on winter nights the ground cools fast and cold dense air settles on the valley floor under a layer of warmer air. This "lid" stops vertical mixing, so smoke and dust stay near the ground until late morning.

   warm air layer (lid)
  ~~~~~~~~~~~~~~~~~~~~~~~~
  /    cold, polluted air  \
 /  hills   [city]   hills  \

3. Low wind speed – especially in winter mornings; pollutants are not dispersed.
4. Little rain in the dry season (November–May) – no washing out of particles.
5. High density – dense settlements and narrow roads in a closed basin concentrate sources.

So the same emission gives a much higher concentration in Kathmandu than in an open plain.

The fecal-oral route is the transmission of pathogens from the faeces of an infected person (or animal) into the mouth of another person, through water, hands, flies, soil or food. Understanding this route is important because it tells us where to put barriers to stop the most common infectious diseases in developing countries like Nepal.

Diseases transmitted

The route (F-diagram)

             +--> Fluids (water) ------+
             +--> Fingers -------------+
 FAECES -----+--> Flies ---------------+--> FOOD --> MOUTH
             +--> Fields/soil ---------+

Importance of understanding the route

1. Identifies the real cause of disease – people often blame fate or weather; knowing that diarrhoea comes from faeces makes them accept toilets and hand washing. Example: cholera outbreaks in Kathmandu valley in the monsoon are linked to contaminated pipe water and tanker water.
2. Helps choose the right barrier
   • Primary barrier: toilets and safe disposal of faeces stop pathogens entering the environment.
   • Secondary barriers: safe water, hand washing, food hygiene and fly control stop them reaching the mouth. Example: in the 2009 Jajarkot diarrhoea epidemic, many deaths were linked to open defecation and unsafe water sources; latrines and safe water were part of the response.
3. Guides engineering design – water supply intakes away from latrines, minimum distance between pit latrine and well (about 15 m or more, and downhill), separate sewer and water pipes, sewage treatment.
4. Focuses health education – teaching hand washing at five critical times (after toilet, after cleaning a child, before cooking, before eating, before feeding a child).
5. Low-cost prevention – hand washing with soap is among the cheapest ways to cut diarrhoea; treatment of water (boiling, chlorine, SODIS) is cheap compared to hospital costs.
6. Protects children – children under five suffer most; malnutrition and stunting are linked to repeated gut infections.
7. Supports national programmes – Nepal's Open Defecation Free campaign (ODF declared in 2019) and Total Sanitation drive are based on breaking this route.
8. Disaster response – after floods or the 2015 earthquake, the first priority was safe water and toilets in camps to prevent outbreaks.

Example of breaking the route in a village: build a pour-flush latrine, put a hand-washing station with soap next to it, protect the spring source, store water in covered vessels and cover food. Each step removes one "F" from the diagram.

Indoor air pollution (household air pollution) is the presence of harmful pollutants in the air inside homes, schools and workplaces. In Nepal its main cause is the burning of solid fuels – firewood, dung cakes, crop residue – and kerosene in open fires or traditional stoves in poorly ventilated kitchens. Main pollutants: fine particles (PM2.5), carbon monoxide, polycyclic aromatic hydrocarbons, formaldehyde, and NO₂.

Severity in Nepal

1. High dependence on biomass – about half of all households still use firewood as the main cooking fuel (Census 2021), almost all of them in rural areas; LPG use is mostly urban.
2. Poor kitchen design – traditional mud stoves or open "chulo" inside the house, with no chimney and small windows. Indoor PM2.5 levels during cooking can be tens of times higher than the WHO guideline.
3. Exposure of women and children – women cook for 3–5 hours a day; infants are carried on the back near the fire. In cold hilly and mountain areas the fire is also used for heating, so exposure lasts most of the day.
4. Health burden
   • Acute respiratory infections (pneumonia) in children under five – a leading cause of child death.
   • Chronic obstructive pulmonary disease (COPD) in women, often in non-smokers.
   • Lung cancer, asthma, tuberculosis, cataract and eye irritation, low birth weight.
   • WHO estimates household air pollution causes millions of deaths a year worldwide; in Nepal it is one of the top risk factors for disease and death.
5. Other indoor sources – tobacco smoke, incense, kerosene lamps, mosquito coils, paints and dampness/mould.
6. Social and economic burden – time lost collecting firewood, medical cost, deforestation pressure.

Suggested counter measures

1. Cleaner fuels – shift to LPG, biogas and especially electric cooking (induction), now promoted by the government as hydropower supply grows.
2. Improved cook stoves (ICS) – stoves with chimneys and better combustion, promoted by AEPC (Alternative Energy Promotion Centre).
3. Biogas plants for households with cattle.
4. Better ventilation – windows, chimneys, smoke hoods; separate kitchen from living and sleeping rooms.
5. Dry fuel – use dry wood, keep children away from the fire.
6. Solar lamps in place of kerosene lamps.
7. Awareness and health education through FCHVs, schools and media about the danger of smoke.
8. Subsidy and policy – subsidies for ICS, biogas and induction cookers; target of "clean cooking for all".
9. No smoking indoors.

Kathmandu has several times topped global real-time rankings (e.g. IQAir) for the worst air quality, with PM2.5 levels in winter and spring many times higher than the WHO guideline. The problem comes from a combination of many emission sources and the valley's closed topography.

Why Kathmandu is so polluted

1. Vehicle emissions – rapid growth in vehicles, many old diesel buses and trucks, poor fuel quality, traffic jams.
2. Road and construction dust – dug-up and unpaved roads, unplanned construction, sand and stone carried uncovered.
3. Brick kilns around the valley and other industries.
4. Open burning of waste, and forest fires in spring.
5. Household fuels in some homes.
6. Topography – bowl-shaped valley, temperature inversion on winter mornings, low wind and no rain in the dry season trap pollutants.
7. Trans-boundary haze from the Indo-Gangetic plain.
8. Rapid unplanned urbanisation – loss of open space and greenery.

Effects

Respiratory and heart disease, eye irritation, reduced life expectancy, flight disruption due to low visibility, loss of tourism and a poor image of the city.

Key takeaways to make Kathmandu a livable city

1. Clean transport
   • Promote electric vehicles (Nepal has hydropower surplus in the wet season) with tax benefits and charging stations.
   • Strong, reliable public transport – electric buses, dedicated bus lanes, possibly BRT/metro.
   • Strict emission testing and removal of vehicles older than 20 years; better fuel quality.
   • Walking and cycling lanes in the core city.
2. Control dust
   • Finish road and pipe works on time; pave and clean roads; water sprinkling.
   • Cover construction sites and trucks carrying sand and soil.
3. Cleaner industries
   • Convert brick kilns to zig-zag or cleaner technology; enforce stack emission standards; move polluting industries out of the valley.
4. Waste management – ban and fine open burning, segregate waste at source, compost organic waste, recycle plastics, operate a proper landfill.
5. Green city planning – parks, green belts, roadside trees, protect open spaces; plan satellite towns to reduce crowding.
6. Clean cooking – electric/induction cooking, phase out kerosene.
7. Monitoring and early warning – a dense air quality monitoring network, public AQI display, health advisories and school closure on very bad days.
8. Law and governance – enforce the Environment Protection Act and National Ambient Air Quality Standards; coordination between metropolitan, provincial and federal bodies.
9. Regional cooperation – work with India and other SAARC countries on cross-border haze and crop burning.
10. Public participation – awareness campaigns, wearing masks, using public transport, reporting polluters.

A livable Kathmandu needs these steps to be done together and continuously, not only in the polluted season.

Indoor air pollution

Indoor air pollution is the presence of harmful gases and particles in the air inside buildings (homes, schools, offices). Main sources are burning of firewood, dung, crop waste and kerosene for cooking and heating in poorly ventilated kitchens, tobacco smoke, incense, paints and mould. Key pollutants are PM2.5, carbon monoxide, formaldehyde and NO₂. In Nepal it mainly affects rural women and children, causing pneumonia, COPD, eye disease and low birth weight.

Severity of environmental and health problems due to air pollution in Kathmandu

Kathmandu valley is one of the most polluted urban areas of South Asia. Annual average PM2.5 is several times the WHO guideline, and in winter and spring the AQI often reaches the "unhealthy" to "hazardous" range.

Causes in brief: vehicle exhaust, road and construction dust, brick kilns, open waste burning, industries, forest fires and trans-boundary haze, made worse by the bowl-shaped valley and winter temperature inversion.

Health problems

1. Respiratory disease – asthma, bronchitis, COPD and pneumonia; hospitals report more patients in the dry season.
2. Cardiovascular disease – PM2.5 enters the blood and increases heart attacks and strokes.
3. Lung cancer risk increases with long-term exposure.
4. Eye, nose and throat irritation, headache, fatigue.
5. Vulnerable groups – children, elderly, pregnant women, traffic police and street vendors are most affected; children's lung growth is reduced.
6. Lower life expectancy – studies estimate that air pollution cuts several years of life for valley residents and is a top risk factor for death in Nepal.

Environmental problems

1. Smog and poor visibility – flights at Tribhuvan International Airport are delayed; mountain views are lost, hurting tourism.
2. Damage to heritage – soot and acidic gases blacken and corrode temples, statues and buildings of the World Heritage Sites.
3. Vegetation damage – dust on leaves reduces photosynthesis; ozone harms crops.
4. Climate impact – black carbon and CO₂ add to warming; black carbon deposited on Himalayan snow speeds melting.
5. Acid deposition from SO₂ and NOₓ.
6. Economic loss – medical costs, lost work days and reduced tourism.

Measures: electric public transport, emission testing, dust control, cleaner brick kilns, ban on open burning, green spaces and air quality monitoring with public warnings.

On-site sanitation

On-site sanitation is a system in which human excreta and waste water are collected, stored and treated (or partly treated) at the place where they are produced, without a sewer network. Examples: simple pit latrine, ventilated improved pit (VIP) latrine, pour-flush latrine with soak pit, septic tank with soak pit, ecosan (composting) toilet. It is low-cost and suitable for rural and peri-urban Nepal.

Crucial role of health education regarding sanitation problems in Nepal

Health education is the process of informing and motivating people to adopt healthy practices and to use health facilities. Building toilets alone does not solve sanitation problems; people must use and maintain them, and change habits. In Nepal this role is crucial because:

1. Changing old habits – open defecation was a long-standing practice in many villages. Education explains the fecal-oral route and the link between faeces and diarrhoea, cholera, typhoid and worm infection, so people accept toilets. The "ODF" campaign was mainly driven by community mobilisation and education, leading to the national ODF declaration in 2019.
2. Sustaining toilet use – after ODF, some households slip back. Education ensures toilets are used, cleaned, repaired and pits emptied safely.
3. Hand washing with soap – teaches the critical times (after toilet, before eating, before feeding children, before cooking). This simple act greatly cuts diarrhoea.
4. Safe water handling – boiling, filtering, chlorinating (e.g. Piyush) and covered storage of drinking water.
5. Food and personal hygiene – washing vegetables, covering food, clean utensils, nail cutting.
6. Menstrual hygiene – reduces stigma and practices like chhaupadi, and improves girls' school attendance.
7. Solid waste and drainage – teaches segregation, composting and avoiding stagnant water (to control mosquitoes and flies).
8. Children as change agents – school WASH programmes and child clubs carry messages home.
9. Women's role – women manage water and hygiene in the home; educating them gives the biggest effect.
10. Disaster preparedness – during floods or after earthquakes (2015), education prevents outbreaks in camps.
11. Community participation – educated users' committees plan, build and maintain water and sanitation schemes and demand services.

Channels used: Female Community Health Volunteers (FCHVs), schools, local radio and FM, street drama, posters, mothers' groups and religious leaders.

Outcome: lower child mortality and malnutrition, fewer outbreaks, cleaner water sources, more dignity and safety for women, and higher productivity.

On-site sanitation is a sanitation system in which human excreta (and sometimes waste water) are collected, stored and treated at or near the place where they are produced, without the use of a sewer network. It is the most common system in rural and peri-urban Nepal because it is cheap and needs little water.

Common types

1. Simple pit latrine – a pit covered with a squatting slab; cheapest.
2. VIP (Ventilated Improved Pit) latrine – a vent pipe with fly screen removes smell and traps flies.
3. Pour-flush latrine – a water-seal pan flushed with 1–3 litres of water into one or two offset pits (twin pit allows alternate use and safe emptying).
4. Septic tank with soak pit – used in towns; sludge settles, effluent goes to a soak pit; needs periodic de-sludging.
5. Ecosan / composting toilet – separates urine and faeces; produces manure.

Advantages

• Low construction and running cost; can be built by households.
• Needs little or no water.
• Suitable for scattered settlements where sewers are not practical.

Disadvantages

• Risk of groundwater contamination if the pit is near a well (keep about 15 m or more away and downhill) or the water table is high.
• Needs safe pit emptying and faecal sludge management.
• Not suitable in very dense areas or rocky ground.

On-site sanitation, together with hand washing and safe water, breaks the fecal-oral route and was the basis of Nepal's ODF campaign.

Indoor air pollution is the pollution of air inside houses and other buildings, mainly by smoke from burning solid fuels (firewood, dung, crop residue) and kerosene for cooking, heating and lighting. It is one of the most serious but least noticed environmental health problems in Nepal.

Severity of the problem in Nepal

1. Widespread use of biomass – around half of Nepali households use firewood as their main cooking fuel (Census 2021); in rural hills and mountains the share is much higher.
2. Traditional stoves and poor ventilation – open fires and mud stoves without chimneys, small windows, kitchen inside the living room. Indoor PM2.5 during cooking can be many times the WHO guideline and far higher than outdoor levels.
3. Long exposure – women spend several hours cooking each day; in cold areas the fire burns most of the day for heating, and families sleep in the same room.
4. Most affected groups – women, infants and young children, and the elderly.
5. Health effects
   • Acute lower respiratory infection (pneumonia) – a major killer of children under five.
   • COPD and chronic bronchitis among women.
   • Lung cancer, asthma and tuberculosis.
   • Cataract and eye irritation.
   • Low birth weight and still births.
   • Carbon monoxide poisoning (deaths are reported in winter from charcoal or gas heaters in closed rooms).
6. Burden of disease – household air pollution is among the leading risk factors for death and disability in Nepal.
7. Environmental and social effects – deforestation from fuel-wood collection, time lost by women and girls collecting wood, soot-blackened homes.

Measures (in brief)

• Clean fuels: LPG, biogas and electric (induction) cooking.
• Improved cook stoves with chimneys (promoted by AEPC).
• Better ventilation and separate kitchens.
• Solar lamps instead of kerosene lamps.
• Awareness through FCHVs, schools and media.

On-site sanitation collects and treats excreta at the place where it is produced (pit latrine, septic tank). Off-site sanitation carries excreta and waste water away from the house through sewers to a central treatment plant.

Differences between on-site and off-site sanitation

Fecal-oral transmission route

It is the route by which pathogens in the faeces of an infected person reach the mouth of another person. It is shown by the F-diagram:

             +--> Fluids (water) ------+
             +--> Fingers -------------+
 FAECES -----+--> Flies ---------------+--> FOOD --> MOUTH
             +--> Fields/soil ---------+       (new host)

1. Fluids – contaminated drinking water.
2. Fingers – unwashed hands.
3. Flies – carry pathogens from faeces to food.
4. Fields – soil and crops contaminated by open defecation or raw night soil.
5. Food – the final carrier into the mouth.

Diseases: diarrhoea, cholera, typhoid, dysentery, hepatitis A/E, polio, worm infections.

Preventive measures against fecal-oral infections

1. Safe excreta disposal – use sanitary toilets; no open defecation; safe disposal of children's faeces (primary barrier).
2. Hand washing with soap after toilet use and before eating, cooking and feeding children.
3. Safe drinking water – protect sources; boil, filter, chlorinate or SODIS; store in covered, clean vessels.
4. Food hygiene – wash raw vegetables and fruits, cook well, eat hot, cover food, clean utensils.
5. Fly control – cover food and latrines, manage solid waste, clean surroundings.
6. Proper siting – keep pit latrines about 15 m or more from wells and downhill; separate water and sewer lines.
7. Sewage treatment before discharge into rivers.
8. Health education in schools and communities.
9. Vaccination (polio, typhoid, rotavirus, hepatitis A) and regular deworming.
10. ORS and zinc for early treatment of diarrhoea.

Air pollution in Kathmandu valley is a severe problem; PM2.5 levels in the dry season are often many times above the WHO guideline, and the city has at times been ranked among the most polluted in the world.

Causes of air pollution in Kathmandu valley

1. Vehicular emission – rapid increase in vehicles (especially motorcycles), old diesel buses and trucks, poor maintenance, adulterated fuel and traffic congestion.
2. Road and construction dust – dug-up roads for pipes and road widening, unpaved roads, construction of buildings, uncovered transport of sand and soil.
3. Brick kilns – burning coal and biomass, mostly in Bhaktapur and Lalitpur from December to May.
4. Industries – cement factories, small industries and diesel generators.
5. Open burning of solid waste including plastic.
6. Household fuel burning – firewood, kerosene.
7. Forest fires in spring and trans-boundary haze from northern India.
8. Topography and weather – bowl-shaped valley surrounded by hills, temperature inversion in winter, low wind speed and no rain in the dry season trap pollutants.
9. Unplanned urbanisation – loss of greenery and open space.

Effects

Health

• Respiratory diseases: asthma, bronchitis, COPD, pneumonia.
• Heart disease, stroke and lung cancer.
• Eye and throat irritation, headache; children, elderly and traffic police most affected.
• Reduced life expectancy.

Environment and economy

• Smog and poor visibility; flight delays at Tribhuvan International Airport.
• Blackening and corrosion of temples and heritage monuments.
• Black carbon contributes to warming and Himalayan snow melt.
• Loss of tourism and higher medical costs.

Possible mitigation measures

1. Transport – electric vehicles and electric public buses; better public transport; emission testing and removal of old vehicles; quality fuel; walking and cycling lanes; traffic management.
2. Dust control – timely completion of road works, paving, water sprinkling, covering construction sites and trucks.
3. Industry – cleaner brick kiln technology (induced-draught zig-zag kilns), relocation of polluting industries, filters and stack standards.
4. Waste – ban and penalise open burning; segregation, composting and recycling.
5. Energy – electric cooking, solar, biogas instead of firewood and kerosene.
6. Greenery – tree plantation, parks, green belts.
7. Monitoring and enforcement – air quality stations, public AQI alerts, enforcement of National Ambient Air Quality Standards and the Environment Protection Act.
8. Awareness – masks on bad days, public participation, school programmes.
9. Regional cooperation to reduce cross-border pollution.

Water pollution is any change in the physical, chemical or biological quality of water that makes it harmful to health or unfit for use. It is caused by adding substances such as sewage, industrial chemicals, fertilisers, pesticides, pathogens or heat beyond the self-purifying capacity of the water body.

Types of water pollution

• Physical – turbidity, colour, odour, temperature (thermal pollution).
• Chemical – organic (BOD-causing matter) and inorganic (arsenic, iron, nitrate, heavy metals).
• Biological – pathogens: bacteria, viruses, protozoa, worm eggs.

Sources and causes

• Untreated domestic sewage (e.g. Bagmati and Bishnumati in Kathmandu).
• Industrial effluent (tanneries, dyeing, distilleries).
• Agricultural runoff with fertilisers and pesticides.
• Solid waste dumping on river banks.
• Open defecation and leaking septic tanks.
• Natural arsenic in Terai groundwater.

Effects

• Water-borne diseases (cholera, typhoid, diarrhoea, hepatitis).
• Arsenicosis, nitrate poisoning.
• Oxygen depletion, fish kill, eutrophication.
• Loss of aesthetic, religious and recreational value; higher treatment cost.

Fecal-oral infection route

Pathogens in faeces of an infected person reach the mouth of another through the "F-diagram":

             +--> Fluids (water) ------+
             +--> Fingers -------------+
 FAECES -----+--> Flies ---------------+--> FOOD --> MOUTH
             +--> Fields/soil ---------+

• Fluids: polluted water from sewage-contaminated sources or pipes.
• Fingers: unwashed hands after defecation.
• Flies: carry faecal matter to food.
• Fields: open defecation, raw excreta on crops, contaminated soil.
• Food: contaminated by the above and eaten.

Mitigation measures

1. Safe excreta disposal – toilets for all households, end open defecation, safe faecal sludge management.
2. Safe water – protect sources, treat water (boiling, filtration, chlorination, SODIS), maintain pipelines, separate water and sewer lines.
3. Hand washing with soap at critical times.
4. Food hygiene – wash, cook and cover food.
5. Fly control – solid waste management and clean surroundings.
6. Sewage and industrial effluent treatment before discharge.
7. Health education and community participation.
8. Vaccination, deworming, and ORS for diarrhoea.

Organic pollution of drinking water is contamination by biodegradable organic matter – human and animal excreta, sewage, food waste, dead plants and animals, and effluent from food, dairy, tannery and distillery industries. These substances are decomposed by micro-organisms, which use up the dissolved oxygen (DO) in water. The strength of organic pollution is measured by BOD (Biochemical Oxygen Demand) and COD. Organic pollution also usually brings pathogens, so it is closely linked with water-borne disease.

Effects: fall in DO and death of fish; bad smell, colour and taste; growth of pathogens; formation of harmful by-products (e.g. trihalomethanes when organic-rich water is chlorinated); eutrophication when nutrients are released. Rivers like the Bagmati in Kathmandu show these effects.

Aerobic decomposition

Breakdown of organic matter by aerobic bacteria in the presence of dissolved oxygen.

• Carbon → CO₂
• Nitrogen → NH₃ → NO₂⁻ → NO₃⁻ (nitrification)
• Sulphur → SO₄²⁻
• Phosphorus → PO₄³⁻

General reaction:

Organic matter + O₂ → (aerobic bacteria) → CO₂ + H₂O + NO₃⁻ + SO₄²⁻ + PO₄³⁻ + new cells + energy

Features

• Fast and complete; final products are stable and harmless.
• No foul smell.
• Consumes DO – if loading is high, DO falls and conditions turn anaerobic.
• Used in engineered systems: activated sludge, trickling filter, oxidation pond, aerobic composting.
• Nitrate and phosphate released can cause algal growth (eutrophication).

Anaerobic decomposition

Breakdown of organic matter by anaerobic bacteria in the absence of oxygen (after DO is exhausted, e.g. in the bottom of polluted lakes, septic tanks, biogas digesters).

• Carbon → CH₄ (methane) + CO₂
• Nitrogen → NH₃ (ammonia), amines
• Sulphur → H₂S (rotten egg smell)
• Phosphorus → PH₃ (phosphine)

General reaction:

Organic matter → (anaerobic bacteria) → CH₄ + CO₂ + NH₃ + H₂S + new cells + small energy

Stages: hydrolysis → acidogenesis (fatty acids) → acetogenesis → methanogenesis (methane).

Features

• Slow, and products are often unstable.
• Foul smell (H₂S, mercaptans), black colour of water and sludge.
• Methane is a greenhouse gas but can be used as fuel (biogas).
• Used in septic tanks, UASB reactors, sludge digesters and biogas plants.

Comparison

 Organic waste in water
        |
   DO present? --yes--> Aerobic: CO2, NO3, SO4
        |
        no
        +-----------> Anaerobic: CH4, NH3, H2S

Inorganic water pollution is contamination of water by non-biodegradable mineral and chemical substances such as arsenic, iron, manganese, nitrate, ammonia, fluoride, hardness salts, heavy metals (lead, chromium, cadmium, mercury) and suspended sediment. These do not decompose and can harm health even at low concentration over long periods.

Severity of the problem in Nepal

1. Arsenic in Terai groundwater – shallow tube wells in districts such as Nawalparasi, Rautahat, Bara, Parsa, Kailali and Bardiya contain arsenic above the national standard (50 µg/L, NDWQS 2062) and far above the WHO guideline (10 µg/L). Long-term drinking causes arsenicosis: skin lesions, keratosis, and cancers of skin, lung and bladder. Hundreds of thousands of people have been estimated to be at risk.
2. Iron and manganese – very common in Terai and Kathmandu valley groundwater; cause reddish colour, bad taste, staining of clothes and utensils, and growth of iron bacteria in pipes.
3. Ammonia and nitrate – Kathmandu valley deep groundwater has high ammonia; shallow wells near septic tanks and farms show nitrate, which can cause methaemoglobinaemia (blue-baby syndrome) in infants.
4. Heavy metals from industries – tanneries (chromium), dyeing, battery and metal works discharge effluent without treatment into rivers such as the Bagmati and in industrial corridors like Biratnagar–Itahari and Birgunj–Pathlaiya.
5. Agro-chemicals – increasing use of fertilisers and pesticides; residues reach streams and shallow wells.
6. Sediment – high turbidity in monsoon rivers from landslides and erosion makes treatment costly and damages hydropower turbines.
7. Hardness – high calcium and magnesium in some hill and Terai sources.
8. Weak monitoring – many small rural and private sources are never tested; people do not know their water is unsafe because many inorganic pollutants have no colour, taste or smell.

Plans to mitigate

1. Testing and mapping – test all tube wells for arsenic, iron and nitrate; mark unsafe wells (red) and safe wells (green); publish a water-quality map.
2. Alternative safe sources – deep tube wells below arsenic layers, piped supply from rivers or springs, rainwater harvesting.
3. Household treatment – arsenic biosand filter / Kanchan filter, iron removal filters, aeration and sedimentation.
4. Community treatment plants – aeration, coagulation, filtration and adsorption plants for iron, manganese and arsenic in towns.
5. Industrial pollution control – enforce effluent standards; require effluent treatment plants; relocate polluting industries to industrial estates with combined treatment; "polluter pays".
6. Safe agriculture – integrated pest management, organic farming, controlled fertiliser use.
7. Sanitation siting – keep septic tanks and pits away from wells to cut nitrate and ammonia.
8. Watershed and river protection – afforestation, river-bank protection, ban on dumping waste in rivers.
9. Health measures – screening and treatment of arsenicosis patients; nutrition support.
10. Awareness – educate users through FCHVs, schools and local bodies.
11. Law and institutions – enforce the National Drinking Water Quality Standards 2062 and the Water Resources Act; strengthen labs at local and provincial level.

Water pollution is the contamination of water by sewage, chemicals, pathogens or sediment that makes it unsafe for use; air pollution is the presence of harmful gases and particles in the atmosphere. Both are among the most serious environmental and health problems in Nepal.

Severity of water pollution in Nepal

1. Urban rivers turned into sewers – the Bagmati, Bishnumati and Dhobi Khola in Kathmandu receive untreated sewage and solid waste; dissolved oxygen is near zero in the dry season.
2. Microbial contamination – many piped and tanker supplies contain faecal coliform; outbreaks of cholera, typhoid and diarrhoea occur every monsoon.
3. Arsenic in Terai groundwater above the national standard (50 µg/L) in districts such as Nawalparasi, Rautahat and Bara.
4. Iron, manganese, ammonia and nitrate in Kathmandu valley and Terai groundwater.
5. Industrial effluent – tanneries, distilleries, dyeing and paper mills in industrial corridors discharge directly into rivers.
6. Agro-chemicals and sediment in rivers and wells.

Severity of air pollution in Nepal

1. Kathmandu valley – PM2.5 often many times the WHO guideline in winter and spring due to vehicles, road dust, brick kilns and waste burning, made worse by the bowl-shaped valley and temperature inversion.
2. Terai cities (Birgunj, Biratnagar, Bhairahawa) – industrial emissions and cross-border haze from the Indo-Gangetic plain.
3. Indoor air pollution – about half of households still cook with firewood, harming mainly women and children.
4. Health burden – air pollution is among the leading risk factors for death in Nepal (respiratory and heart disease, lung cancer).
5. Other effects – flight delays, damage to heritage, black carbon speeding snow melt.

Plans to solve the problem effectively and in a short time

Short-term (1–2 years, quick wins)

• Strict vehicle emission testing; remove vehicles older than 20 years from the valley.
• Finish and pave dug-up roads; sprinkle water; cover construction sites and trucks.
• Ban and fine open burning of waste; daily waste collection.
• Air quality alerts and school closures on hazardous days; masks for vulnerable groups.
• Test drinking water sources; chlorinate supplies; household treatment (boiling, filters, chlorine) during the monsoon.
• Stop direct dumping of waste into rivers; enforce existing effluent standards with fines.

Medium-term (3–5 years)

• Electric public buses and incentives for electric vehicles and induction cooking, using Nepal's hydropower.
• Convert all brick kilns to cleaner zig-zag technology.
• Complete sewer interceptors and wastewater treatment plants along the Bagmati (Bagmati Action Plan).
• Arsenic-safe deep tube wells and community treatment plants in the Terai.
• Effluent treatment plants in industrial estates.

Long-term and supporting

• Land-use planning, green belts and satellite towns.
• Continuous monitoring networks for air and water with public data.
• Health education through schools and FCHVs.
• Clear roles for federal, provincial and local governments under the Environment Protection Act 2076.
• Regional cooperation on cross-border haze.

Quick results come from enforcing existing rules and fixing visible sources (dust, burning, old vehicles, untreated water); lasting results need investment in clean transport and sewage treatment.

Pollution

Pollution is the introduction by humans or nature of harmful substances or energy (pollutants) into the environment – air, water, soil – in amounts that damage health, living organisms, property or the climate. Types: air, water, soil, noise, thermal, radioactive and light pollution. Examples: vehicle smoke, sewage in rivers, plastic waste in soil.

On-site sanitation

On-site sanitation is a system where human excreta are collected, stored and treated at the place where they are produced, without a sewer network – e.g. pit latrine, VIP latrine, pour-flush latrine, septic tank with soak pit, ecosan toilet. It is cheap and suitable for rural Nepal; the pit should be at least about 15 m from a water source.

Health education

Health education is the process of giving people knowledge and motivation to adopt healthy behaviour – using toilets, washing hands, treating drinking water, keeping food clean. Without it, toilets and water systems are not used or maintained properly. In Nepal it is spread through FCHVs, schools, radio and community groups.

Fecal-oral infection transmission route

Pathogens in faeces of an infected person reach the mouth of another person through the F-diagram:

             +--> Fluids (water) ------+
             +--> Fingers -------------+
 FAECES -----+--> Flies ---------------+--> FOOD --> MOUTH
             +--> Fields/soil ---------+

• Fluids – contaminated water; Fingers – unwashed hands; Flies – carry faeces to food; Fields – open defecation, contaminated soil and crops; Food – final carrier.
• Diseases: diarrhoea, cholera, typhoid, dysentery, hepatitis A/E, polio, worms.

Effective prevention measures

1. Sanitary toilets for every household and no open defecation (primary barrier).
2. Hand washing with soap after toilet and before eating or cooking.
3. Safe water: protect sources, boil, filter or chlorinate; covered storage.
4. Food hygiene: wash, cook well and cover food.
5. Fly control and solid waste management.
6. Health education, vaccination (polio, typhoid, rotavirus) and ORS for diarrhoea.

Fecal-oral transmission route

The fecal-oral route is the way pathogens (bacteria, viruses, protozoa, worm eggs) in the faeces of an infected person reach the mouth of another person and cause disease – e.g. cholera, typhoid, diarrhoea, dysentery, hepatitis A/E, polio and worm infections. It is explained by the F-diagram:

             +--> Fluids (water) ------+
             +--> Fingers -------------+
 FAECES -----+--> Flies ---------------+--> FOOD --> MOUTH
             +--> Fields/soil ---------+       (new host)

1. Fluids – drinking water contaminated by sewage or open defecation.
2. Fingers – hands not washed after defecation.
3. Flies – sit on faeces, then on food.
4. Fields – soil and vegetables contaminated by excreta.
5. Food – contaminated by any of these and eaten.

Barriers: toilets (primary barrier); safe water, hand washing, food hygiene and fly control (secondary barriers).

Evaluating health education regarding water and air pollution

Health education is evaluated by checking whether it has changed knowledge, attitude and practice (KAP) and, finally, health outcomes.

1. Knowledge – survey whether people know:

• that diarrhoea comes from faeces in water and food;
• how to treat water (boiling, filtering, chlorine);
• the sources and health effects of smoke, dust and vehicle exhaust, and what the AQI means.

2. Attitude – do people believe these practices matter and are willing to act (e.g. willing to pay for a toilet, LPG or improved stove)?

3. Practice (behaviour) – observe actual behaviour:

• toilet use, hand washing with soap at critical times, covered water storage;
• use of improved cook stoves or clean fuel, ventilation in kitchens, no waste burning, use of masks on bad-air days.

4. Outcome indicators – fewer diarrhoea cases in health post records, fewer respiratory infections in children, lower indoor smoke levels, measured water quality at household level.

5. Methods – baseline and follow-up surveys, observation checklists, focus group discussions, school quizzes, and comparison with a village that did not receive the programme.

Observations in Nepal:

• Health education was very effective for sanitation – the community-led campaign helped Nepal declare itself Open Defecation Free in 2019, and hand washing has improved, especially after COVID-19.
• It is weaker for water treatment at home and for air pollution: many households still drink untreated water and cook with firewood, and city residents know little about PM2.5.
• Education works best when combined with affordable options (cheap filters, subsidised stoves, electric cooking) and enforcement (ban on waste burning, emission tests).

So health education is necessary and cost-effective, but must be measured regularly and backed by infrastructure and policy.

Water pollution is any physical, chemical or biological change in water quality that makes it harmful to living beings or unfit for its intended use.

Sources of water pollution

1. Point sources – enter at one identifiable location:

• Domestic sewage outfalls.
• Industrial effluent pipes (tanneries, distilleries, dyeing, paper).
• Hospital waste water.
• Discharges from treatment plants.

2. Non-point (diffuse) sources – come from a wide area:

• Agricultural runoff with fertilisers and pesticides.
• Urban storm water carrying oil, dust and garbage.
• Open defecation areas and leaking septic tanks.
• Landfills and solid waste dumped on river banks (leachate).
• Erosion and landslides (sediment).

3. Natural sources – arsenic, iron, fluoride from rocks; volcanic ash; decaying vegetation.

Types of water pollution

Also classified by water body: surface water pollution (rivers, lakes) and groundwater pollution (wells, aquifers). In Nepal the main problems are pathogenic and organic pollution in urban rivers like the Bagmati, and arsenic, iron and ammonia in groundwater.

Air pollution is the presence of harmful gases and particles in the atmosphere; climate change is the long-term change in global temperature and weather patterns, mainly due to greenhouse gases from human activities. The two are closely related because they mostly share the same sources – burning of fossil fuels and biomass.

How air pollution causes climate change

1. Greenhouse gases – CO₂ from vehicles, industries and power plants, CH₄ from agriculture and waste, N₂O from fertilisers, and CFCs trap outgoing heat and warm the Earth.
2. Short-lived climate pollutants – black carbon (soot from diesel engines, brick kilns, cook stoves) absorbs sunlight and warms the air; deposited on Himalayan snow and glaciers it darkens the surface and speeds melting. Ground-level ozone is also a greenhouse gas.
3. Aerosols – sulphate particles reflect sunlight and cause local cooling, and change cloud and monsoon patterns.

How climate change worsens air pollution

1. Higher temperatures speed the formation of ground-level ozone and smog.
2. More droughts and heat increase forest fires, adding smoke (as seen in Nepal in spring).
3. Changes in wind and rain patterns can trap pollutants longer.
4. More pollen and dust in a warmer, drier climate.

Common solutions (co-benefits)

• Replace fossil fuels with hydropower, solar and wind.
• Electric vehicles and public transport.
• Clean cooking (electric, biogas) instead of firewood.
• Cleaner brick kilns and industries.
• Forest protection and tree planting.

Cutting air pollution therefore improves public health immediately and slows climate change at the same time.

Health education is the process of informing, motivating and helping people to adopt and maintain healthy practices and lifestyles, and to use health and sanitation facilities properly.

Importance

1. Prevents disease – teaches hand washing, toilet use and safe water, cutting diarrhoea, cholera and typhoid (breaking the fecal-oral route).
2. Changes behaviour – turns knowledge into practice, e.g. ending open defecation (Nepal declared ODF in 2019 largely through community education).
3. Makes infrastructure effective – toilets, water taps and improved stoves are used and maintained only if people understand their value.
4. Reduces cost – prevention is cheaper than treatment for families and the state.
5. Protects vulnerable groups – mothers and children (nutrition, immunisation, ORS, clean cooking to avoid smoke).
6. Awareness of pollution – about smoke, dust, AQI, safe waste disposal.
7. Community participation – people take part in planning and managing water and sanitation schemes.
8. Reduces superstition and stigma – e.g. menstrual hygiene, chhaupadi.

It is delivered through schools, FCHVs, health posts, radio, street drama and posters.

Pathogenic pollution of drinking water is the contamination of water by disease-causing micro-organisms (pathogens) – bacteria, viruses, protozoa and helminth (worm) eggs – that come mainly from human and animal faeces. It is the most dangerous form of water pollution in developing countries because even a small dose can cause disease and outbreaks.

Main pathogens and diseases

Indicator organism: since pathogens are hard to test, water is tested for faecal coliform / E. coli. Nepal's National Drinking Water Quality Standards require 0 E. coli per 100 mL.

Sources: open defecation near sources, leaking septic tanks and sewers, cross-connection of sewer and water pipes, uncovered wells and springs, animal waste, unsafe storage at home, flood water.

Transmission route (fecal-oral route)

             +--> Fluids (water) ------+
             +--> Fingers -------------+
 FAECES -----+--> Flies ---------------+--> FOOD --> MOUTH
             +--> Fields/soil ---------+       (new host)

1. Fluids – drinking contaminated water directly (water-borne).
2. Fingers – unwashed hands touch food or mouth (water-washed diseases, due to lack of water for hygiene).
3. Flies – carry faecal matter to food.
4. Fields – contaminated soil and vegetables.
5. Food – prepared with contaminated water or hands.

Prevention measures

At source and in the system

1. Safe excreta disposal – toilets for all, no open defecation; latrines at least about 15 m from and downhill of water sources.
2. Protect intakes, springs and wells (fencing, sealed covers, sanitary seal).
3. Treatment: sedimentation, filtration (slow sand filter) and disinfection by chlorination with residual chlorine in the supply.
4. Maintain pipelines; avoid intermittent supply and cross-connection with sewers.
5. Regular water quality testing for E. coli.

At household level 6. Boiling, ceramic or biosand filters, chlorination (e.g. Piyush), SODIS (solar disinfection). 7. Safe storage in covered, narrow-mouthed vessels; use a ladle, not hands.

Hygiene and health 8. Hand washing with soap at critical times. 9. Food hygiene and fly control. 10. Health education, vaccination (typhoid, polio, rotavirus, hepatitis A) and ORS/zinc for diarrhoea.

Technology is both a cause of and a solution to water and air pollution.

Technology as a cause

• Industrial technology – factories, thermal power plants and brick kilns release smoke, SO₂, NOₓ and particulates; tanneries, dyeing and chemical plants discharge toxic effluents and heavy metals into rivers.
• Transport technology – petrol and diesel vehicles are a major source of urban air pollution (CO, NOₓ, PM2.5) and of oil-polluted runoff.
• Agricultural technology – chemical fertilisers and pesticides pollute rivers and groundwater (nitrate, eutrophication).
• Consumer technology – plastics and e-waste, which are often burnt or dumped.
• Mining and construction – dust in air and sediment in water.

Technology as a solution

For air pollution

• Clean energy: hydropower, solar, wind, biogas.
• Electric vehicles, catalytic converters, cleaner fuels (Euro standards).
• Filters, electrostatic precipitators and scrubbers in industries; zig-zag brick kilns.
• Improved cook stoves and induction cooking.
• Real-time air quality monitoring sensors and satellite data.

For water pollution

• Sewage treatment (activated sludge, oxidation ponds, constructed wetlands).
• Effluent treatment plants in industries.
• Drinking water treatment: filtration, chlorination, UV, arsenic and iron removal filters.
• Low-cost household technologies: SODIS, biosand filters.
• Sensors and GIS for water quality monitoring.

Conclusion of the note: the problem is not technology itself but the choice and management of it. Appropriate, cleaner technology with proper regulation can reduce pollution while supporting development.