Research: Gas stove emissions measured at the tiniest level

A new study undertaken by Purdue University in Indiana has found that  a gas stove can emit more nano-sized particles into the air than internal combustion engined vehicles, possibly increasing the risk of developing asthma or other respiratory illnesses.

These particles are extraordinarily small. At Air Quality News we tend to deal with PM10 and the smaller PM2.5. These measure 10 micrometers (aka 10µm) and 2.5 micrometers (aka 2.5µm) respectively.

The work at Purdue focussed on nanocluster aerosols which are between one and three nanometers. And there are 1,000 nanometers to a micrometer. To put it another way, they are 0.001–0.003 µm. 

These aerosols are solid/aqueous particles suspended in the atmosphere but not much is known about how they grow and spread indoors because they’re very difficult to measure.

As recent studies have found that children who live in homes with gas stoves are more likely to develop asthma, the Purdue team attempted to discover how much of a threat these minute particles may be.

Using state-of-the-art air quality instrumentation they were able to measure these tiny particles down to a single nanometer while cooking on a gas stove in a ‘tiny house’ lab. They collaborated with Gerhard Steiner, a senior scientist and product manager for nano measurement at Grimm Aerosol. 

The  house has all the features of a typical home but is equipped with sensors for closely monitoring the impact of everyday activities on a home’s air quality. In this testing environment the team collected extensive data on indoor nanocluster aerosol particles during realistic cooking experiments.

They found that as many as 10 quadrillion nanocluster aerosol particles could be emitted per kilogram of cooking fuel. Comparing these findings with known outdoor air pollution levels, which are more regulated and understood than indoor air pollution, they found these emissions were equal to, or even greater than, those produced from ICE vehicles.

This would mean that adults and children could be breathing in 10-100 times more nanocluster aerosol from cooking on a gas stove indoors than they would from car exhaust while standing on a busy street.

Brandon Boor, an associate professor in Purdue’s Lyles School of Civil Engineering, who led this research said: ‘After observing such high concentrations of nanocluster aerosol during gas cooking, we can’t ignore these nano-sized particles anymore.

Purdue PhD student Satya Patra modelled the various ways that nanocluster aerosol could transform indoors and deposit into a person’s respiratory system.

The models showed that nanocluster aerosol particles are very persistent in their journey from the gas stove to the rest of the house. Trillions of these particles were emitted within just 20 minutes of boiling water or making grilled cheese sandwiches on a gas stove.

Even though many particles rapidly diffused to other surfaces, the models indicated that approximately 10 billion to 1 trillion particles could deposit into an adult’s airways and tracheobronchial region of the lungs. 

The nanocluster aerosol coming from the gas combustion also could easily mix with larger particles entering the air from butter, oil or whatever else is cooking on the gas stove, resulting in new particles with their own unique behaviors.

It is possible that a gas stove’s exhaust fan would redirect these nanoparticles away from your respiratory system, but that remains to be tested.

Boor said: ‘Since most people don’t turn on their exhaust fan while cooking, having kitchen hoods that activate automatically would be a logical solution. Moving forward, we need to think about how to reduce our exposure to all types of indoor air pollutants. Based on our new data, we’d advise that nanocluster aerosol be considered as a distinct air pollutant category.’