Delhi Students Turn Fans Into Rs 140 Air Purifiers, Bringing Cleaner Air to More Than 10,000 Pupils

A classroom solution built around an ordinary fan

A filter costing about Rs 140 to manufacture has helped bring classroom air filtration to more than 10,000 students in Delhi, according to the Diana Award organisation. Developed through Project Vayu, the device fits over an ordinary table or wall fan, using its airflow to trap tiny pollution particles rather than requiring schools to buy a separate purifier.

Krish Aggarwal, a Class 12 student at Sanskriti School, has been named on the 2026 Diana Award Roll of Honour for his work on the initiative. He co-founded Project Vayu with Samarth Meattle, a Class 11 student at Vasant Valley School. Their approach focuses on schools serving families with limited incomes, where buying and maintaining conventional air purifiers can be difficult.

The project's pilot installed 602 filters across 295 classrooms, reaching about 8,000 students. Schools receive the filters free, with replacements delivered monthly and fans supplied where classrooms need them. The next planned expansion covers another 45 schools across New Delhi.

The Rs 140 figure is the manufacturing cost of a replacement filter, rather than the price of an entire appliance. Its practical appeal comes from using equipment schools may already own: a fan supplies the moving air, while a removable cover supplies the filtration.

Project Vayu says a test in a closed room reduced PM2.5 concentrations from 158 to 11 micrograms per cubic metre within an hour. Alongside the award recognition, those figures explain the interest in a design that combines inexpensive materials, simple installation and recurring support for schools.

How the filter catches particles

Project Vayu uses electret media, a material made with fibres that hold an electrical charge. Those fibres attract and capture fine particles as air passes through them. A simple comparison is static electricity drawing small pieces of paper towards a charged object, although the filter is specifically designed to capture airborne pollution.

PM2.5 means particulate matter measuring 2.5 micrometres or less across. These particles are small enough to travel deep into the lungs. In Delhi classrooms, polluted outdoor air can enter through doors, windows and other openings, leaving children exposed indoors as well as outside.

An elastic edge secures the filter around the grille of a table or wall fan. When the fan starts, moving air inflates the material into a balloon shape. Teachers can fit or replace it in under a minute without tools, adhesive or technical assistance, according to the founders.

The inflated shape gives the material more than five square feet of filtering surface, compared with about 1.4 square feet across a standard fan face. Using those figures, the filter provides more than three and a half times the surface area. Spreading airflow across a larger area helps air pass through the material while particles are captured.

Project Vayu lists a pressure drop of 0.23 inches of water column. Pressure drop describes how much resistance a filter puts in the path of moving air. Keeping that resistance low matters because an ordinary fan must push air through the material using its existing motor.

What the room test recorded

Project Vayu's reported test started with a PM2.5 concentration of 158 micrograms per cubic metre and ended at 11 after 60 minutes. That is a reduction of 147 micrograms per cubic metre, or approximately 93%. The measurement describes how much fine particle pollution was present in a given volume of air.

The project describes that test as taking place in a closed room of approximately 168 square feet; a December 2024 description put the room size at roughly 200 to 250 square feet. Both descriptions reported a reduction of more than 90% within an hour.

Room size and the use of a closed space matter when explaining the result. A classroom with open doors or windows can receive a continuing supply of particles from outdoors. The number of occupants, the fans used and the amount of outside air entering the room all affect the conditions in which filtration operates.

The performance figures are attributed to Project Vayu. Details of an independent testing protocol, repeated trials and measurements across occupied classrooms were not given. Schools considering the system therefore have a specific project test result alongside the practical experience of the classroom rollout.

What Rs 140 pays for

Project Vayu breaks the manufacturing cost into Rs 85 for filter media, Rs 15 for the elastic lining and Rs 40 for stitching and transportation. The figures add up to Rs 140, with the filtering material accounting for about 61% of the total.

Schools participating in the programme receive the filters without paying that amount themselves. The initiative also supplies fans where needed and delivers fresh filters monthly. Its affordability for schools depends on both the inexpensive design and the support that pays for production and distribution.

A December 2024 description listed a different pricing arrangement: Rs 150 plus goods and services tax for school filters supported by donations, and Rs 500 plus tax for retail filters. It also listed table fans at approximately Rs 2,000 plus tax. Those figures describe school and retail pricing at that stage, while Rs 140 is the manufacturing cost now being cited.

Replacement is a recurring expense. At Rs 140 each, one fresh filter every month would cost Rs 1,680 to manufacture over 12 months, before any additional programme costs. A classroom using several filters would require a corresponding number of replacements.

The earlier description estimated that filters could last between two weeks and one month during peak pollution, depending on surrounding particle levels. The current monthly delivery model gives teachers a regular replacement schedule, while the shorter estimate shows how heavy pollution can increase material needs.

From four schools to more than 10,000 students

The pilot distributed 602 filters across four schools in Delhi and the surrounding National Capital Region, covering 295 classrooms and approximately 8,000 students. That works out to just over two filters per classroom on average, although the number installed in each individual room was not specified.

The Diana Award organisation's profile credits Project Vayu with subsequently benefiting more than 10,000 students through distribution in schools serving disadvantaged communities. Compared with the pilot's approximate 8,000 students, the later figure represents an increase of more than 2,000.

The classroom focus reflects the founders' concern about children whose families cannot afford air purifiers at home and whose schools face similar financial limits. Placing filters in schools gives the project a way to reach groups of children through one institution rather than distributing an appliance to each household.

Teachers also have a direct role in keeping the system running. Because they can fit the elastic cover themselves, replacement does not require a technician to visit every classroom. The continuing work shifts towards producing filters, delivering them and making sure schools receive supplies regularly.

The students and the manufacturing partnership

Aggarwal and Samarth Meattle are identified as Project Vayu's current founders. Savya Meattle helped shape the initiative early on before leaving to study at Stanford University. A December 2024 description named all three as founders, placing Savya in Class 12, Aggarwal in Class 10 and Samarth in Class 9 at that time.

Hollingsworth & Vose, a filtration materials manufacturer headquartered in Massachusetts, worked with the students on research and development. The company supplied 700 metres of filter media, giving the initiative material with which to develop and distribute its design.

The partnership connects two different parts of the project: the students' effort to make classroom filtration affordable and a manufacturer's experience with materials that capture particles. Choosing suitable material is central to the design because the filter must trap fine pollution while allowing an ordinary fan to move air through it.

Project Vayu says it holds copyright on the filter design; the December 2024 description said the students and Hollingsworth & Vose had jointly filed for copyright. The company also sponsored material for the pilot, helping support the initial distribution to schools.

How the project developed

Project Vayu's public milestones stretch from an initial school pilot to an expansion programme and international recognition. Some earlier figures were targets rather than completed installations, an important detail when following how far the initiative has progressed.

• December 19, 2024: A description of the project recorded 602 filters across four schools and 295 classrooms, reaching about 8,000 students.
• 2025 target: The team aimed to install 5,000 school filters, with a longer ambition to exceed 30,000 across North India.
• 2026 recognition: Aggarwal was named on the Diana Award Roll of Honour, with the award organisation crediting the initiative with reaching more than 10,000 students.
• Next planned rollout: The team is preparing to reach another 45 schools across New Delhi while expressing an ambition to expand nationally.

Samarth Meattle, the Vasant Valley School student who co-founded the initiative, described the development and expansion plans:

"We started the project three years ago and conducted a pilot last year. This year, we are expanding it and do not want to limit it to Delhi but take it across the country," Meattle said.

The December 2024 account already recorded the same pilot totals of 602 filters and 295 classrooms. Those dated figures provide the clearest reference for the pilot's reported scale. Completion figures for the earlier targets of 5,000 and 30,000 filters have not been announced.

What the award recognises and expansion requires

The Diana Award was established in memory of Diana, Princess of Wales, to recognise young people for social action and humanitarian work. Aggarwal's place on its 2026 Roll of Honour recognises his work on indoor air pollution, alongside advocacy for environmental measures supported by evidence and greater participation by young people.

For participating schools, the immediate benefit is practical: access to filtration without buying a separate purifier, installation that teachers can manage and replacement supplies provided by the initiative. Those arrangements are as central to the programme as the shape or price of the filter.

Expansion to 45 more schools would require a larger continuing supply of materials and finished filters. The founders aim to work with Delhi government bodies, charities and corporate sponsors to reach more government schools. No date has been given for completing that rollout.

The pilot figures show why expansion involves more than counting schools. Its 295 classrooms used 602 filters, and each filter needs periodic replacement. A larger programme must therefore plan around the number of classrooms and fans, as well as recurring production and delivery costs.

Project Vayu addresses particles in classroom air while using existing fans to keep equipment costs down. Its immediate task is to extend that model to more schools and maintain the replacement service that keeps the filters in use.

Key Points

• Project Vayu's filters cost about Rs 140 each to manufacture and fit ordinary table or wall fans.
• Krish Aggarwal has been named on the 2026 Diana Award Roll of Honour for his work on the initiative.
• The pilot installed 602 filters in 295 classrooms, reaching about 8,000 students across four schools.
• The Diana Award organisation says the project has since benefited more than 10,000 students.
• Schools receive filters free, with monthly replacements and fans supplied where needed.
• Project Vayu reports that PM2.5 fell from 158 to 11 micrograms per cubic metre during a test lasting one hour in a closed room.
• The team plans to expand to another 45 schools across New Delhi and eventually reach schools elsewhere in India.