Nov 1 2018
On September 20, 2017, when Hurricane Maria struck Puerto Rico, the storm completely destroyed the electrical grid of the island, which left many people without electric power for months on end.
The absence of electricity as well as other damage caused by the storm prevented air-quality monitoring in numerous areas. Now, a group of researchers has demonstrated that cost-efficient sensors running on solar energy can be utilized for tracking air pollution following a disaster. They have reported the results of their study in ACS Earth and Space Chemistry.
Even three months after the wake of Hurricane Maria, half of the Puerto Rico population still did not have electricity, while the other half faced frequent power outages. Therefore, backup generators that ran on diesel or gasoline were extensively used, which possibly contributed to increased air pollution. However, in the majority of areas, official air-quality data were not available owing to the damage caused by the storm. R. Subramanian and coworkers wondered whether this gap could be filled by cost-efficient, solar-powered sensors that they had earlier developed to track air quality—known as Real-time Affordable Multi-Pollutant (RAMP) monitors.
In November 2017, the researchers deployed four RAMPs at various places in the San Juan Metro Area of Puerto Rico. Over a period of one month, the devices were able to measure a variety of pollutants, for example, nitric oxide, sulfur dioxide, nitrogen dioxide, carbon monoxide, and particulate matter. The team discovered that the concentrations of carbon monoxide and sulfur dioxide increased between 4:00 a.m. and 8:00 a.m. local time every day, perhaps because of nighttime atmospheric conditions that lock in pollutants.
The levels of black carbon, carbon monoxide, and sulfur dioxide were closely correlated, implying that the pollutants originated from the same combustion source (possibly diesel—and gas-powered generators). Furthermore, the RAMP data indicated that the levels of sulfur dioxide surpassed the air quality standards of the U.S. Environmental Protection Agency on nearly 80% of the days at the time of the monitoring period. According to the researchers, areas that are prone to natural disasters and other emergencies should have a set of cost-effective, calibrated air-quality monitors in their preparedness plans.
Funding from the U.S. Environmental Protection Agency is acknowledged by the authors.