Concentrations of NO2 in the atmosphere are highly variable in space and time: they typically vary by one order of magnitude within each day and quite substantially from one day to another because of the variations in emissions (for example the impacts of commuter traffic, weekdays and weekend days) as well as changes in the weather conditions. This is why, even if observations are available on a daily (currently available from satellites) or even hourly (ground-based observations) basis, it is necessary to acquire data for a substantial period of time in order to check that a statistically robust departure from normal conditions has emerged.
Cloud cover is a factor that needs to be taken into account as well.
The U.S. National Library of Medicine’s TOXNET, an interactive map that tracked pollution, chemical exposure, toxicology and other data, was shut down last month. The move has been criticized in the context of the Trump administration’s rollback of environmental protections, but the NLM insists that the decision was theirs. The data mapped by TOXNET is available from other sources, but, and this is the point, not as easily or centrally accessible. [The Hill, Newsweek]
Earlier this year, we shared the first results of this effort with pollution levels throughout the city of Oakland.
We’re just beginning to understand what’s possible with this hyper-local information and today, we’re starting to share some of our findings for the three California regions we’ve mapped: the San Francisco Bay Area, Los Angeles, and California’s Central Valley (the Street View cars drove 100,000 miles, over the course of 4,000 hours to collect this data!) Scientists and air quality specialists can use this information to assist local organizations, governments, and regulators in identifying opportunities to achieve greater air quality improvements and solutions.
President Trump’s budget proposes eliminating the EPA’s Great Lakes Restoration Initiative. That fact is no doubt what’s behind two publications posting maps earlier this month, only a couple of days apart, showing the environmental stresses on the Great Lakes basin.