Clearing the Air

Written on: April 1, 2018 by Dr. Steve Bennett

A recent study published in the journal Science runs counter to much of the current scientific understanding of volatile organic compound (VOC) impact on air quality. However, evaluating new information, its credibility and the claims put forward are a fundamental part of being a critical thinker—whether you are a consumer choosing between two new products or a scientist evaluating a new study. That’s why we are all taught the basics of the scientific method in grade school and why I expect rigorous scientific reasoning from myself and my colleagues.

The new study, entitled “Volatile Chemical Products Emerging as Largest Petrochemical Source of Urban Organic Emissions” by McDonald et al., purports that current VOC inventories and models underestimate the portion of consumer product-related VOC emissions and that emphasis on ozone reductions to achieve better air quality may need to be revisited.

When it comes to sources of man-made air pollution, mobile sources (cars, trucks, etc.) have been one of the largest pieces of the pie for more than 30 years. That is why they have been highly regulated—with great success.

With the significant decrease in emissions from mobile sources, it is not surprising that other sources of emissions would become more significant in the total emission inventory. When one piece of a pie shrinks, the others look bigger in comparison. However, in this case, it should not be lost that the pie as a whole has also gotten smaller—other categories of emissions have also been regulated and reduced.

VOC emissions from consumer products have dramatically decreased due to tighter regulations and innovation within the industry. HCPA member companies have invested hundreds of millions of dollars to develop new or reformulated products with lower amounts of VOCs, thereby lessening the impact on air quality. The efforts driven by both regulators and industry have resulted in an overall 50% reduction in the VOC emissions attributed to consumer products, with even greater reductions in certain product categories nationwide, especially in California.

HCPA’s initial review of the McDonald et al. study highlights several concerns with their modeling and conclusions, such as:

  • Use of 1990 national data on consumer products to model 2012 emissions without considering the significant changes consumer product formulations have undergone in that period
  • Utilization of aerial monitoring measurements conducted during the summer in Pasadena and applying them throughout the rest of California and the entire U.S.
  • Assignment of VOCs exclusively to consumer products without considering other emission sources
  • Choice of surrogate when working on something as complex and specific as photochemical reactivity, which likely overestimated the degree of impact

All of this isn’t to say that the study is based on “bad science.” It can be hard to accept new information when it contradicts what we previously thought, however science which goes against the last 30 years of our understanding needs to be scrutinized. Appropriately, the study identifies the need for further investigation, for example, an improved understanding of photochemical reactivity and secondary organic aerosol (SOA) formation, not only with VOCs, but also low vapor pressure volatile organic compounds (LVP-VOCs).

It will be highly instructive to compare the comprehensive and definitive California Air Resource Board (CARB) Consumer Product Survey data of more than 400 categories of consumer products that were sold in California during 2013–2015 leading to emissions identified in this study. This will help all of us determine what, if any, future adjustments to existing or new regulations are necessary to achieve an even better air quality. Pursuing additional research will better clarify the concerns HCPA and others have identified and move the scientific understanding forward.

For more than 30 years, HCPA and our member companies have worked collaboratively with legislators, regulators, non-governmental organization (NGOs) and stakeholders at all levels of government to significantly improve air quality in California and across the U.S. Since 1989, HCPA, building upon a strong scientific foundation, has actively engaged in negotiating provisions of every one of the numerous rulemaking procedures CARB has conducted to continually tighten California’s comprehensive and stringent consumer products regulations. This has led to a tremendous improvement in the air quality for all Californians. HCPA members also worked with the U.S. Environmental Protection Agency (EPA) to develop the current national VOC regulation for consumer products. Further, HCPA member companies worked with the Ozone Transport Commission (OTC) to develop the Consumer Products Model Rule, which has been adopted in 16 states and the District of Columbia.

HCPA and its members remain committed to providing sustainable products that achieve rigorous emissions standards while helping consumers and workers live cleaner, healthier and more productive lives. Please contact me at if you would like to learn more about our efforts. SPRAY