CAPE ELIZABETH — The recent Portland Press Herald articles on emissions of potentially hazardous substances from Global Partners and Sprague Energy petroleum storage tanks describe serious issues for South Portland. It is surprising that tons of hazardous vapors are legally permitted to be released into the surrounding residential areas. Even more surprising, those legal emissions have been exceeded for years and regulatory agencies have failed to inform the city.

The first issue is how ongoing test results will be interpreted. Attempts are now being made to measure the levels of contaminants in the air, but this approach is fraught with difficulties. Regulatory limits for exposure to individual hazardous air pollutants do exist. However, they are for industrial settings and typically refer to exposure over a 40-hour workweek for healthy young male workers. The situation in South Portland involves 24-hour exposure 365 days a year. The population includes pregnant women, children and the elderly – a much more vulnerable population.

This situation is analogous to the chemical waste dump in the infamous Love Canal neighborhood of Niagara Falls, New York. State regulators struggled with determining what was a safe level of contaminants for residents to breathe. They rejected the industrial regulations and instead determined the normal amounts that residents of typical neighborhoods in other communities were breathing in their air and compared those averages to the air in Love Canal. Any amount of contaminant in excess of the normal was deemed a potential health threat.

The same approach needs to be applied to South Portland. Without doing a single measurement, the human olfactory system tells us that on bad days, the air around the tank facilities reeks of oil fumes. On those same days, the air near my home in Cape Elizabeth and in other parts of South Portland has no odor.

If you look at the material safety data sheet for the type of product stored, there will be health warnings listed for breathing those vapors. For example, the Valero Energy material safety data sheet for No. 6 fuel oil states: “Harmful if inhaled. … Suspected of causing cancer. Suspected of damaging fertility or the unborn child. May cause damage to organs (blood, liver, kidney) through prolonged or repeated exposure.” So, the answer for South Portland is that no resident should be exposed to fuel odors in their neighborhood above those found in neighborhoods where no odor is evident.

The city’s second issue is choosing a way to reduce emissions so that no oil odors are present. A potential solution already exists. It is called a vapor recovery unit, and these units are commonly in use in Texas on storage tanks for crude oil. The units capture the vapor by turning it back into liquid, which can then be sold. In Texas, vapor recovery units quickly pay for themselves. In South Portland, the recovered vapors may not be as valuable and the payback may be longer, but we are talking about tons of product being recovered.

One alternative to vapor recovery is to burn the vapors. The problem with this cheaper solution is increased carbon dioxide, carbon monoxide and sulfur dioxide emissions. Another solution is a unit that removes oil mist. Removing mist (small particles of oil) is fine, but it does nothing to remove the toxic vapors.

Now, experienced mechanical engineers need to enter this discussion to find the best technical fix. But for now, my money is on vaper recovery units.