Cleaning products could expose people to pollution at the same rate as cars, study says

Cleaning products have become more ubiquitous than ever in the last two years, but a new study suggests their use may come with a health risk. 

Researchers in the US have performed real-time observations in ‘realistic indoor conditions’ that mimic the work of indoor professional cleaners. 

Commercial cleaners for sanitising indoor surfaces may deposit small pollutant particles into human respiratory tracts at rates equal to or higher than aerosols from vehicles, they found. 

The new findings may have implications for people who have worked heavily with disinfectant sprays during the Covid pandemic.

Some staff have been spending entire working days frequently dousing touch-point surfaces in offices to prevent SARS-CoV-2 transmission.  

The study has been led by Colleen Rosales, an environmental scientist at University of California, Davis and published today in Science Advances.  

Scientists have known that cleaning indoor surfaces with disinfectants can generate secondary indoor pollutants as gases and aerosols.

But there have been few studies capturing secondary organic aerosol formation in realistic indoor conditions. 

A secondary organic aerosol (SOA) is a molecule produced via oxidation over several generations of a parent organic molecule. 

‘SOA accounts for a major fraction of the global atmospheric aerosol burden,’ said Professor Annele Virtanen, an atmospheric scientist at University of Eastern Finland, who was not involved in the study. 

‘Understanding the mechanism of formation and the properties of SOA is therefore important to estimate its effects on climate, air quality, and human health.’

To learn more about SOA formation indoors, the US team focused on monoterpenes, a class of volatile organic compounds (VOCs).

Monoterpenes are released from a very wide range of sources including cooking, foodstuffs, plants and multiple kinds of fragranced products.  

In an indoor setting, monoterpenes can mix with ozone to form particles that may bury inside the lungs.  

Road transport is an source of both greenhouse gases and air pollutants, being responsible for significant contributions to emissions of carbon dioxide, nitrogen oxides and tiny particulate matter

The team used a commercial monoterpene-based household cleaner to mop surfaces inside an enclosed, mechanically ventilated test room within a research building in a forested area for 12 to 14 minutes. 

As the floor was mopped, the researchers measured gas-phase precursors, oxidants, radicals, secondary oxidation products, and aerosols in real time. 

They calculated that a person using a monoterpene-based cleaning product would first inhale about 30 to 40 micrograms of primary volatile organic compound per minute as they begin mopping. 

As secondary organic aerosols form when the product interacts with the air in the room, the person would then inhale about 0.1 to 0.7 micrograms of these particles per minute. 

The authors suggest that maintaining indoor background ozone levels below 1 part per billion before mopping could minimise the buildup of pollutant particles. 

VOCs that are currently being used in aerosols are less damaging than the ozone-depleting chlorofluorocarbons (CFCs) they replaced in the 1980s. 

CFCs, which are classified as halocarbons, damage Earth’s protective ozone layer that shields us from harmful ultraviolet rays generated from the Sun. 

Recognising the danger of CFCs, the Montreal Protocol was agreed in 1987, which led to their phase-out and, recently, the first signs of recovery of the Antarctic ozone layer.