During this time of heightened anxiety about Covid-19 with increasing attempts to clean and disinfect everything around us, making sure you get it right when using cleaning products has become more important than ever. In the present Covid-19 lockdown, accidental poisonings in the US have risen dramatically.
There is a common misconception that you’ll get better results if you mix different household cleaning products. The truth is that mixing them together can be very dangerous because the combination you get can produce unexpected chemical reactions that can be very harmful to your health.
Products usually list ingredients, highlight risks and warn against mixing. Nevertheless, there have been several high-profile cases recently where two or more common cleaning agents have been mixed with serious consequences. Statistics show that there are several thousand unwitting accidents of this kind every year in the US alone.
Recently incidents of mixing cleaning agents together on the floor of a Buffalo Wild Wings restaurant resulted in the generation of toxic fumes, which killed the general manager. Two weeks later, chemical fumes from mixing cleaning chemicals at a Red Robin restaurant in Woburn sent three employees to the hospital. Another recent incident resulted from a woman in the US sterilising groceries with a mixture of bleach and vinegar – chlorine is thought to have been generated. She was hospitalized with breathing difficulties but recovered.
These dangerous chemical reactions can also happen with little warning in our homes, especially in small and enclosed environments like bathrooms. Some toilet bowl cleaners contain acid, some glass cleaners contain ammonia and many products contain bleach.
According to the Centers for Disease Control and Prevention (CDC) home poisonings are up by 20%. These problems occur in most cases, when people inadvertently mix different cleaning agents. There were 45,550, 911 calls related to exposure to disinfectant and cleaning agents, almost two-thirds of the incidents involving bleach and most of the others non-alcohol disinfectants and hand sanitizers.
What is the difference between cleaning, disinfecting and sanitizing? Cleaning products remove debris, dirt and dust. Sanitizing reduces contaminants to a level where health is not affected. Disinfecting kills all microorganisms and is mostly used in hospitals to prevent infectious diseases. Most households do not need to sanitize or disinfect with a few exceptions notably bodily fluids. Restaurants need to sanitize food contact surfaces as stated in local regulations.
Bleach is the most common chemical used. There are many cleaning products referred to as ‘bleach’. They usually contain an aqueous solution of sodium hypochlorite (NaOCl) at various concentrations with added surfactants, anti-foaming agents and fragrances. Bleach is corrosive and can damage skin and eyes and be lethal if ingested. Sodium hypochlorite reacts with ammonia, drain cleaners, and other acids. Pool chemicals frequently containing calcium hypochlorite or sodium hypochlorite, should not be mixed with household cleaners, and used carefully.
Ammonia (NH3) is also used in aqueous solution at 5% to 10% concentrations. It is widely used to clean glass, porcelain and stainless steel, as well as removing fatty deposits from ovens. It is corrosive and toxic.
Solid sodium hydroxide, caustic soda and solutions of this basic chemical are widely used to break down fatty deposits in ovens and drains. It is corrosive and can damage the skin and eyes if it comes into contact with them or if the fumes are inhaled.
When bleach is mixed with ammonia, toxic gases called chloramines are produced. Exposure to chloramine gas can cause: Coughing, Shortness of Breath, Chest Pain, Wheezing, Nausea, Watery Eyes, Irritation to the throat, nose and eyes, Pneumonia and fluid in the lungs
Acids are less common in domestic cleaning agents but are used in commercial ones. However, solutions of two or more acids are also sold as sprays for bathroom cleaning to cut the need for scrubbing. They are both corrosive and toxic.
If used correctly and separately each is effective at its job, although many of them are corrosive and toxic on their own. Mix them – something emergency services have always been warning people not to do to tackle coronavirus – and they will not be as effective and could even lead to tragic consequences.
When chlorine bleach is mixed with an acid, chlorine gas is produced. Chlorine gas and water combine to make hydrochloric or hypochlorous acids. Chlorine gas exposure, even at low levels, almost always irritates the mucous membranes (eyes, throat and nose), and causes coughing and breathing problems, burning and watery
eyes, and a runny nose. Higher levels of exposure can cause chest pain, more severe breathing difficulties, vomiting, pneumonia, and fluid in the lungs. Very high levels can cause death. Chlorine can be absorbed through the skin, resulting in pain, inflammation, welling and blistering. Hydrochloric acid also causes burns to the skin, eyes, nose, throat, mouth, and lungs.
The chemistry of ill-defined mixes of the various cleaners – acids, ammonia, hypochlorite and hydroxides – is complicated. Part of the problem is that mixing often generates a lot of gas and heat, which may rupture or burn sealed containers. There is also the issue of decomposition that occurs spontaneously in normal use and prior to any deliberate or inadvertent mixing of cleaning agents. Such decomposition can generate species such as hypochlorous acid (HOCl) that can then feed additional reactions with other cleaning products.
Mixing hypochlorite with ammonia would see the breakdown of the hypochlorite to generate hypochlorous acid and thence hydrochloric acid. This will then react with more hypochlorite to release chlorine gas, hazardous in itself but then further reacting with ammonia to generate corrosive and toxic chloramines (R2NCl). The distinctive smell of swimming pools is the result of hypochlorite reacting with nitrogen compounds found in sweat and urine to generate volatile organic chloramines.
There is also the risk of generating chloroform if bleach is mixed with products containing alcohol. Mixing acid and bleach will also generate the strong oxidising agent hypochlorous acid, which will further react with hypochlorite to generate chlorine gas. This is an equilibrium reaction the balance of which depends on the acidity of the solution:
Safer alternatives to hazardous cleaning products exist for nearly every type of household cleaner. Look for products with credible third-party certification such as Green Seal, EcoLogo and Safer Choice. This means that the products have been reviewed for standards such as performance, health, environment and sustainability. Manufacturers with these third-party certifications report product ingredients. Also look for smaller producers which may not have funds for the third-party process, but who are transparent about their ingredients. Even though these products are safer, make a practice of not mixing cleaning solutions. Acid is listed and 99.7% of ingredients are listed as “other.” It’s best to use cleaning products that list all ingredients.
Read product labels carefully so that you can choose a product that is the best fit for the application you need it for. Products are formulated for specific soil types. For example, toilet bowl cleaners are designed to remove hard water stains. Glass cleaners are formulated for fast drying. Disinfecting products are designed to kill bacteria, not for cleaning. So choose the right cleaner for the job. Choosing a green product for the wrong type of cleaning will not work well.
If you read “safe when used as directed” on product labels, be wary. Products should be safe under all conditions, especially for children and pets.
The first signs of incompatibility between cleaning products could be a hissing noise, vapors, heat and bubbling. If the volume of the mixture is small, it is advisable to immediately dilute the mixture by adding copious amount of water. Ensure increased ventilation if possible or leave the location to avoid breathing in the vapor. Wait until the visible signs of any reaction are gone and clean up the remaining liquid wearing gloves and dispose of the wastes down the drain. If there is any sign that the reaction
is still taking place add more water but do not try to neutralize the mixture with other chemicals. However, if the cleaning products are reacting in high volumes and in difficult to access locations such as deep in sink’s pipes, then the advice may be somewhat different.
If safe to do so, open windows and start externally venting extractor fans. A call to the emergency services should be made and emergency care for severe symptoms sought. Specific advice from a poison centre should be sought for mild symptoms if they do not subside after a few minutes in fresh air. Of course, there are specific rules and protocols in laboratories where other hazardous chemicals might be involved and ventilating may not be advisable.
As ever it’s safety first – READ labels and seek ADVICE!