A healthcare worker in north-west London quit her job after she was refused permission to wear a protective face mask, the Guardian has learned.

In her resignation letter (below), Tracy Brennan chastised her superiors at Hillingdon Hospitals NHS foundation trust for forbidding her from wearing a surgical mask she had bought to protect herself – and the patients she was caring for – from contracting the deadly virus.

Brennan, a healthcare assistant, which is also sometimes referred to as an auxiliary nurse, said she had returned to work after self-isolating for 14 days because her daughter had shown symptoms of Covid-19. She said that patients in the ward where she was working, which was not a coronavirus treatment ward, felt comfortable with her wearing the surgical mask and some positively encouraged her to do so.

She wrote in the letter: “Upon arriving to work on Tuesday morning, whilst still wearing a mask, you asked me for a word in your office. You outlined to me that wearing a mask wasn’t following the trust policy and asked me to remove it. I responded stating that I wasn’t pleased with this instruction and defended myself stating that I was uncomfortable not wearing a mask while dealing with patients who may be carriers of Covid, however I adhered to the request.”

She said that later that day, while taking blood, a patient coughed into her unprotected face but, despite relaying details of the incident, she was still refused permission to wear her mask.

Brennan wrote: “With a heavy heart and sadness, I feel I have no alternative but to hand this letter in as my formal resignation and will be unable to work my notice due to not being allowed to wear sufficient personal protective equipment (PPE) for the duties I perform.”

NHS England has insisted that lack of PPE is down to distribution problems rather than shortages, but many remain sceptical. On Friday, a group of organisations including Doctors in Unite and the Doctors’ Association UK issued a demand that the government repurpose industry to produce adequate quantities of PPE, including face masks, preferably to the highest specification.

A spokesman for the Hillingdon trust said: “Our trust takes the safety of all our staff extremely seriously and we follow national guidelines, as set out by Public Health England. We regularly update staff on the types of PPE and the rules for its use ... We are also providing extra support to our staff during the current emergency both for their physical and their mental health and wellbeing.”

The Department of Health and Social Care said: “In the past two weeks the NHS supply chain have delivered 397m pieces of PPE equipment. While we are confident that enough supply is now reaching the frontline, we appreciate there were limited distribution problems to begin with while we dealt with a new demand caused by this emerging epidemic.”

Tracy Brennan’s letter

I am writing to inform you of the recent issues … over the last two days. As you are aware, I have been in self-isolation for the past 14 days due to my daughter having symptoms of Covid-19 and, upon returning to work, I have attempted to wear a surgical mask, which I have supplied myself. The reason for wearing the mask is to reduce the risk of me potentially spreading the virus to patients and colleagues whilst also protecting myself from contracting the virus from said patients and colleagues.

Whilst carrying out my duties on Monday, I made sure to ask the patients if they felt comfortable with me wearing the protective mask and all gave their consent, with some also stating that they felt more comfortable with me wearing it due to being in such close proximity.

Upon arriving to work on Tuesday morning, whilst still wearing a mask, you asked me for a word in your office. You outlined to me that wearing a mask wasn’t following the trust policy and asked me to remove it. I responded stating that I wasn’t pleased with this instruction and defended myself stating that I was uncomfortable not wearing a mask while dealing with patients who may be carriers of Covid, however I adhered to the request.

Later that day, whilst taking blood from one of our patients, they accidentally coughed in my face. I told you what had just happened, however, you informed me I was still unable to wear my mask.

With a heavy heart and sadness. I feel I have no alternative but to hand his letter in as my formal resignation and will be unable to work my notice due to not being allowed to wear sufficient PPE for the duties I perform. I love my job and have loved working with you and the girls in the ward and miss you all dearly.

Please keep safe in these troubling times.

Yours sincerely,

Tracy Brennan