McDowell's paternal family came from Ulster, and owned a chain of off-licences and grocery stores on the northside of Dublin.
Her grandfather, William J. McDowell, was a journalist who edited the Belfast Morning News before moving to Dublin in 1883 to join the staff of the Freeman's Journal.
She was assigned as supervisor of the clerical works in the union's office in 1923, with the aim of rationalising all administrative procedures and cutting operational costs.
Over time, McDowell held numerous administrative and official positions within the union, with specific interest in representing and working with mental health nurses, textile workers, and printers.
From January 1951 to May 1954, McDowell took an extended leave of absence to sit on the government's prices advisory committee.
"[2] During McDowell's tenure, many of the industries represented by the union saw widespread automation, leading to part-time or irregular shift work, which was often taken up by married women returning to the workforce.
In 1964, she was sceptical of the national wage agreement that had been worked out between Irish unions and employers, primarily as it did not give women the £1 minimum basic increase guaranteed to men.
During her time as head of the union, McDowell saw a ten-week lockout of IWWU members in printing in 1965, and in 1966 a strike of sugar confectioners.