The California Environmental Protection Agency Air Resources Board (ARB) states: “CA’s population reached 24 million people. Total registered vehicles surpassed 17 million and vehicle miles traveled is 155 billion. Cumulative CA vehicle emissions for [nitrogen oxides] and [hydrocarbons] remain at 1970 levels of 1.6 million tons/year despite a rise of 45 billion in VMT over these 10 years.” This was in 1980.
Meanwhile, in 2000, ARB notes: “California’s population grows to 34 million with 23.4 million registered vehicles in state. Annual vehicle miles traveled (VMT) reaches 280 billion miles. Cumulative CA vehicle emissions for nitrogen oxides and hydrocarbons are about 1.2 million tons per year. This is 200,000 tons/year less than 1990 despite an increase in VMT of 40 billion miles per year.” (Comparable data from 2001 to present from this exact same source is not available).
By year 2005, state VMT rose to roughly 346.75 billion. I arrived at this figure based on my (visual) interpretation of data in Figure 7 in “California’s Progress Toward Clean Air,” an April 2012 report from the California Air Pollution Control Officers’ Association (CAPCOA).
From what I was able to determine, California VMT in 2005 was approximately 950 million miles per day and hence 346.75 billion miles yearly total. Using extrapolation, state population in 2010 was approximately 38 million, which would put California population at around 36 million in 2005. Remember, these are all ballpark estimates.
Not only this but in this same figure is displayed total nitrogen oxide (NOx) plus volatile organic compound (VOC) amounts. At about 11,500 daily tons of NOx + VOC in 1980, this declined to roughly 6,000 daily tons in 2005, or a 92 percent decrease. It is clear that between 1980 and 2005 in California, NOx, HC (hydrocarbons) and NOx + VOC coming from pavement-based transportation sources has been on the retreat.
This is good news despite growth in population, vehicle population and vehicle miles traveled.
Not so much so, on the other hand, is news regarding fine particulate matter (PM 2.5) emissions coming from the same sector. During the same time period, results overall, are mixed.
For instance, from 1980 to 2005, tons per day (TPD) of PM 2.5 went from 53.734 to 61.104. One bright spot is for the Heavy Heavy-Duty Diesel Trucks (HHDV) classification: This went from 38.485 (the single largest road-based PM 2.5 contributor) to 32.544 TPD. The decline continued even beyond 2005 for in 2008, HHDV PM 2.5 TPD decreased to 29.91. But, to be fair, between 2005 and 2008, fine particulate emissions from California road-based mobile sources fell back from 61.104 to 58.043 TPD. What’s important to note, however, is that between 2005 and 2008, state VMT flat-lined at roughly 950 million miles as revealed in the “California Progress Toward Clean Air” report (Figure 7). Based on information in Figure 7 though, projections are a rise in VMT will resume beginning in 2010.
What it all means
Clearly the numbers indicate that progress with respect to pavement-based motor vehicle emissions had occurred. While there have been significant strides made in terms of reductions in ozone precursors nitrogen oxides and volatile organic compounds released from state on-road transportation sources, emissions of fine particulates from said sources overall has not fared nearly as well. Nevertheless, there has been progress.
Moreover, California still being one of America’s dirtiest air offenders, with Bakersfield, Fresno, Hanford, Los Angeles, Merced, Modesto, Sacramento and San Diego in California among the nation’s cities known for having notoriously bad air according to the American Lung Association, it should come as no surprise then that the Golden State’s air quality regulations would be among this nation’s tightest or most stringent and they are. Besides the criteria pollutants already named, other pervasive air contaminants, meanwhile, include sulfur oxides (SOx), sulfur dioxides (SO2) and reactive organic gases (ROG), in addition to carbon monoxides (CO). And health impacts range from coughing and wheezing to asthma and heart attacks and premature death.
Where to go from here
What all this should be pointing to is unless there is greater reliance on low, ultra-low and/or zero-polluting vehicles, significant advancement in clean fuels, increased dependence on alternative modes (i.e., walking, biking, public transportation), better methods of managing transportation and traffic flow, improved land-use development policy and practice and other pollution-fighting approaches, the expectation is mobile-sourced pollution levels – particle pollution in particular – will rise, especially considering population too is expected to rise.
With that said, efforts to curb said emissions must be relentless.
Image above: U.S. National Archives and Records Administration