This paper is a stock-take of the current importance of different sources of volatile organic compounds in both indoor and outdoor air.

The authors calculate that the combined effects of the many different chemicals that are in daily use in our cities are already equivalent to the emissions from transport.

As we move away from diesel and petrol engines for our transport, the relative effect of these other chemicals will clearly become greater. In addition, as we move to more densely populated cities, the actual concentrations of these chemicals will increase.

It is therefore timely that we reconsider the regulation of these products, which currently is aimed at reducing ozone pollution in cities.

The authors point out that these chemicals can produce fine particles in the atmosphere, which are now of greater concern for human health than ozone.

This study published in Science is of note because it presents a case that emissions of volatile organic chemicals (VOCs) found in a myriad of consumer products, for example, cleaning agents, paint thinners, adhesives, pesticides, coatings, and personal care products, contribute significantly to VOC emissions in industrialised countries.

The study maintains that this fraction is now as high as for VOC emissions from transportation e.g. driving petrol and diesel vehicles, given the steady decline in transportation emissions over the last two decades from the introduction of catalytic converters, better engine technology and fuel make-up.
 
This study is important because it has used measured VOC data of outdoor and indoor air, as well as mass calculations of the sources and contribution of VOCs, to conclude that emissions of VOCs from consumer products are making an increasing contribution to VOCs in our air.

This is of significance as VOCs undergo complex chemical reactions in our atmosphere to form secondary organic aerosols, which contribute to particulate matter in air. Exposure to fine particulate matter in air is associated with an increased risk of mortality and cardiovascular and respiratory disease.

Overall, if verified, these findings have implications for how governments control, mitigate and regulate VOC emissions from volatile chemical products, including consumer products, to help reduce particulate matter formation. This in turn has the potential to impact on human health

Air pollution is a major human health risk – and to clean up our air and reduce that risk, it is critically important to understand where that air pollution comes from.
 
Although we think about pollution spewing straight out of cars or power plants, a large fraction of air pollution actually comes from chemical reactions in the atmosphere. A necessary starting point for that chemistry is a group of hundreds of molecules collectively known as 'Volatile Organic Compounds' (VOCs).
 
This study shows that advances in technology and regulation mean that VOCs released to the air by burning gasoline and diesel have dropped dramatically (in the U.S. at least). This means that – in a relative sense – nearly twice the amount of these harmful VOCs in the atmosphere comes from chemical products as comes from fuel. The bulk of those chemical products are everyday consumer products such as cleaning agents, printer ink, and fragrances.
 
Overall, there is a hidden good news story here – VOCs from fuel use have started to decrease so overall the air is cleaner. Since the contribution from fuels has dropped, it is not surprising that chemical products, which have not been as tightly regulated, are now responsible for a larger share of the VOCs.
 
An important implication of this work is that these chemical products have largely been ignored when constructing the models that we use to predict air pollution – which impacts how we respond to and regulate pollutants.
 
If we want to keep air pollution to a minimum, it will become increasingly important to take into account the VOCs from these chemical products, both in our models of air pollution and in our regulatory actions. This applies not only to outdoor air pollution but particularly to indoor air pollution – a major concern as we spend most of our time indoors