Some surprises in Northside air quality sampling results


Naphthalene detected near Webber Park, methylene chloride near Broadway and the city limits, benzene at many Northside locations. These chemical findings are some of the May 2014 results of an air quality study underway.

In February, sampling caught whiffs of naphthalene in the middle of the Northside and several instances of methylene chloride at different spots on the Northside. But in November 2013, there was nothing at a dangerous level.

Will knowing the results of this ongoing Air Quality Study scare people out of the city, or parts of it? Officials say they’ll take that chance, betting that more people will appreciate knowing the data and how it’s being put to use.

One way the data is being used is to encourage businesses such as printers and dry cleaners to switch from solvent-based to water-based processes, as the city and state fund Green Business grants covering one-third to two-thirds the cost of converting.

The study, which relies on volunteers to gather samples for potentially 72 chemicals over 58.4 square miles resulting in 69,120 data points, will take its fourth of eight samples in August, and end with the August 2015 collection.

To reward volunteers and keep their interest, they (myself included) were invited to a talk and discussion July 8 at the Central Library.

When we sample, we simply open a valve on a “canister” which slowly vacuums in the ambient air. It has a hook for the intake so that it won’t suck in rain. After three days, we close the valve and bring the canister to Pace Analytical’s labs in Southeast Minneapolis. In North Minneapolis, the park board hosted some of the test canisters at various parks, in addition to residential volunteers.

To the volunteer who asked about “scaring people,” Patrick Hanlon, Environmental Initiatives Manager, and Jenni Lansing of Environmental Services for the city said there’s nowhere else in the country that this level of detail will be collected. Other cities and areas could be as bad, they just don’t know it.

And it gets better, Lansing said, there are some University of Minnesota Civil Engineering PhD candidates who will be applying a land use regression analysis which should give very accurate data.

The first results showed some things predictable, but also surprises. They tested for a wide range of chemicals (though no particulates, which would have been much more expensive and probably inconclusive as to sources, they said). They wanted to measure chemicals they suspect might reach concentrations in excess of Health Risk Values assigned by the Minnesota Department of Health. Most of the chemicals cause cancer during a lifetime of exposure.

Broad picture, the air quality has been getting better in the last several years, Hanlon said. “But there have been anomalies with ground level ozone,” therefore the study is sampling VOCs, volatile organic compounds. “NOx + VOC + heat and sunlight lead to smog and ozone,” the presentation stated. NOx is a generic term for mono-nitrogen oxides NO and NO2 (nitric oxide and nitrogen dioxide), according to Wikipedia. They are produced from the reaction of nitrogen and oxygen gases in the air during combustion.

Hanlon’s pie chart showed that non-road sources such as businesses actually slightly surpass gasoline vehicles as sources (28 to 26 percent) and “point sources” make up 6 percent of VOC sources.

Benzene, which is from auto exhaust, and formaldehyde have been trending upward and getting toward dangerous levels.

Officials encouraged volunteers to let their neighborhood and business organizations know that they can request someone from the study come out and meet with them for more information on the study; in fact, for $165.50 per sampling canister and a volunteer willing to secure it, open and close it, an organization or business may request to host a sampling…city staff would want to know 6-8 weeks ahead of time. It’s too late for the August 25-27 sampling event coming up, but the next one is in November.

What were the surprises? Lansing said “We were a little surprised at the PERC results outside of businesses.” She said the common dry cleaning solvent was found further away from potential sources than they would have expected. The industry is moving away from using PERC (perchloroethylene or tetrachloroethylene), and there are just nine dry cleaners left in the city who have yet to convert.

“Methylene chloride, we didn’t expect it at all. And naphthalene,” Lansing said.

Naphthalene is probably best known as mothballs, but it’s also a compound produced when things burn – cigarette smoke, auto exhaust, smoke from forest fires.

Methylene chloride is used in various industrial processes, including paint stripping, pharmaceutical manufacturing, paint remover manufacturing, and metal cleaning and degreasing.

“I was surprised at how open businesses were to having canisters,” Lansing said during audience discussion of exerting consumer pressure and encouragement to businesses to use solvent-free practices.

The next due date for Green Business grants is April 15, 2015. For information, go to

To request a presentation, to volunteer, or to request to host a sampling canister, call 612-673-3023 email and mention your zip code if leaving a message.

The web address with raw data from the study is at To view each event or type of chemical, click on the middle of three icons located (on the screen) under the details button, and uncheck everything you don’t need to see. Mousing over a point will give you the address of the sampling. Lansing said she will be changing the format in September when she adds the August data. If the link changes, we will post it at