Research finds that ironing, washing, and cleaning in homes could be damaging the health of occupants

Zehnder UK has found that astounding pollution levels are being caused by everyday indoor activities. These include ironing, washing clothes and cleaning in homes.

The poor state of indoor air quality in the UK

Volunteers from varied home environments and lifestyles were chosen to record all activities taking place in their house while using indoor air quality monitors placed in various rooms. These were used to record dust particles and dangerous chemicals present in the air.

The data highlighted significant concentrations of levels of PM2.5 particles (fine dust molecules). These can lead to serious health conditions such as asthma and other respiratory diseases, allergies, dementia, mental health issues and insomnia.

It also revealed dangerous levels of volatile organic compounds (VOCs) in the air. These can lead to allergies, asthma, headaches, dizziness, eye and nose irritation, nausea, eczema, mental health issues, cognitive impairment and cancer.

What are safe levels?

In terms of PM2.5 the World Health Organisation (WHO) guidelines are 10 µg/m3 (micrograms per cubic metre). A recent Breathe London survey suggests that 90% of schools are exceeding this, and traffic on London roads averages 23 µg/m3.

For VOCs there are no formal guidelines. In part, this is because VOCs are a group of different chemicals, and definitions of exactly what to include in this group varies. It is estimated, however, that concentrations of VOCs in indoor air are two to five times greater than those in outdoor air, and sometimes may reach levels 1,000 times higher.

Zehnder’s analysis we have used the following VOC risk classification, using parts per billion as our measure, meaning that for every billion molecules of air there is one molecule of a VOC.

<1000 ppb                                         Acceptable

>1000 ppb and < 10,000 ppb         Some health risk

>10,000 ppb                                      May produce serious health risk

It’s worth noting that these are generous averages – other commentators place the bar much lower, with levels between 50 ppb and 325 ppb considered acceptable.

What Zehnder found out

Research revealed that:

  • The use of cleaning products can raise the levels of VOCs in the house by 25,623%, from 64 ppb to an extremely toxic 16,565 ppb
  • Carrying out washing can raise the levels of PM2.5 from 2.2 µg/m3 to 109.7 µg/m3 – that’s nearly five times more than is present on a busy London road
  • Even a spot of ironing (using a water spray) can see VOC levels raise to concerning levels. They rose by 1,635%, from 109 ppb to 1,892 ppb
  • Removing and reapplying nail polish also poses significant risks to our health. This activity saw VOC levels skyrocket by 4157%, from 200 ppb to 8,514 ppb

What does this mean for UK homes?

With winter setting in we can expect VOC concentration in indoor air to rise higher and higher. It is believed to be three to four times higher than the VOC concentrations during the summer.

The cause of this is poor ventilation leading to low rates of air exchange between the indoor and outdoor environment as a result of tight-shut windows.

It has been discovered that as many as 50 to 300 different VOCs may be present in the indoor air in which we spend 90% of our time.

Some examples of these compounds include:

  • Formaldehyde
  • Toluene
  • Benzene
  • Xylene
  • Perchloroethylene
  • Ammonia (the most likely culprit in the nail varnishing readings we took)

In Approved Document F, UK building regulations concerning ventilation that are currently in draft proposal due for publication in 2020 and the World Health Organization (WHO) guides first published in 2010, measures are placed against different chemicals that can cause harm to health.

These are based on WHO guidance:

 Pollutant Exposure limit Exposure time
Carbon monoxide 100 mg/m3 15 minute average
30 mg/m3 1 hour average
Nitrogen dioxide (NO2) 200 μg/m3 1 hour average
40 μg/m3 1 year average
Formaldehyde 100 μg/m3 30 minute average
TVOC 300 μg/m3 8 hour average


In terms of cleaning and household products these are widely present in, but not limited to:

  • Aerosol spray products, including health, beauty and cleaning products
  • Air fresheners
  • Chlorine bleach
  • Detergent and dishwashing liquid
  • Dry cleaning chemicals
  • Rug and upholstery cleaners
  • Furniture and floor polish
  • Oven cleaners

As part of its recent investigations the Clean Air Day campaign has referred to UK households as ‘toxic boxes’, due to the number of air pollution particles that are trapped inside.

With everyday activities such as cleaning, ironing, washing clothes and applying nail varnish ready for a Saturday night, causing potentially dangerous air to breathe, it’s hard to disagree.


The study was conducted across five different homes, each with a different set of variables (pets, no pets, windows open, windows closed, ventilation fans and units on and off etc). Each subject had the device for 5 days and took a diary during that time, detailing activities and variables.

The Awair air monitoring device was used for the study, placed in different rooms such as the kitchen, living room, bedroom and hall, throughout each part of the study.

Awair’s sensors are designed and tested to accurately identify the five key factors of air quality. Each sensor is strategically placed to ensure optimal airflow and consistent readings.

The data was analysed using the Awair app, which produces graphs and averages for five factors: Temperature, Chemicals, PM2.5 particulates (dust), CO₂ levels and humidity.