Polish soprano and mezzo-soprano.

Born in Warsaw on 1 January 1892. She developed most of her career in Spain, accompanied by Manuel de Falla in many occasions.

On 15 September 1917, she premiered Joaquín Turina's "Poema en forma de canciones, Op. 19" (1917) at the Teatro del Casino in San Sebastián, with Francisco Cotarelo on the piano. One month later, on 9 October, she joined Manuel de Falla, the artists Julio Antonio, Pablo Uranga and Gil Bergasa, the Count and Countess of Morella, and other distinguished guests, to the inauguration of the schools founded by the painter Ignacio Zuloaga in the town of Fuendetodos (Zaragoza), birthplace of Francisco de Goya. She sang in the Parish church, accompanied by Falla on the harmonium; after the mass, she appeared on the balcony of Fuendetodos Town Hall, and sang the jota from Falla's "Siete canciones populares españolas" a cappella.

In December 1917, Lahowska did a concert tour around several Spanish cities, with Falla accompanying her on the piano. The tour began at the Residencia de Estudiantes in Madrid, on 4 December, and headed north, stopping at Teatro Rosalía de Castro in La Coruña, Teatro Jovellanos in Gijón, Teatro Campoamor in Oviedo, Sociedad Filarmónica de Bilbao and Teatro Principal in Burgos. Their programme included pieces by Frédéric Chopin, Gabriel Fauré and Claude Debussy, as well as Jesús Guridi's "Cinco melodías populares vascas", Baldomero Fernández's "Tres melodías asturianas" and Falla's own "Siete canciones populares españolas".

At the Debussy tribute concert -held at the Ateneo de Madrid on 27 April 1918-, where Falla once again accompanied her on piano, Aga sang "Les Cloches", "Le Faune'"from "Fêtes galantes", "Ariettes oubliées", "Rondel (Charles d'Orléans)" from "Trois chansons de France" and "Mandoline", while Arthur Rubinstein performed other works by the French composer. On 16 March 1919, she gave a song recital with the pianist Frederic Longàs at the Palau de la Música Catalana. That same year, her friend Ignacio Zuloaga painted her a portrait. On 22 May 1920, she premiered Jesús Guridi's opera "Amaya" at the Coliseo Albia in Bilbao, singing the part of the pagan priestess Amagoya. In 1922 she gave a concert in Granada, organised by the city's philharmonic society.

Aga Lahowska married Howell Dawson Mundell in London, on 12 August 1925. In May 1945 she travelled to Australia and gave song recitals with Henri Krips at several venues, including the Sydney Conservatorium of Music, where she sang works by Falla, Gabriel Fauré, Debussy and others. She also gave concerts of Spanish music in China, Japan, Palestine, Singapore, Egypt and India. She was a correspondent for the Polish daily "Kurier Warszawski". She was professionally active until 1948.