Tag: Imperial Valley

Publication alert

On May 22, 2025

Our research article, “Heat-related rest-break recommendations for farmworkers in California based on wet-bulb globe temperature” is out today, in Nature Communications Earth & Environment:
https://lnkd.in/gJK5MiFi

The heat season is around the corner and we are hoping that this paper will provide a starting point for discussing heat-related policies in California and elsewhere.

What did we do?

We determined rest-break requirements for the farmworkers of the Imperial and Coachella Valleys in southern California, using high-resolution outputs from a validated Weather Research and Forecasting Model (WRF) at 1-km grid.

How? Please be more specific.

We calculated how often thresholds of heat stress indicators were exceeded in farmworkers’ working environments and translated those exceedances into rest breaks needed for their safety. We considered three existing policy guidelines that use wet-bulb globe temperature (WBGT), heat index (HI), or dry-bulb temperature (DBT) thresholds to specify rest-break requirements.

What is the finding?

WBGT was the most protective among the three heat stress indicators so we used it to derive recommended rest duration considering the acclimatization status of the workers, seasons, and work-shifts. Recommended rest breaks range from 2 to 32 minutes per work-hour between April and August. These recommendations can be directly incorporated into regulations such as the California Code of Regulations (T8 §3395 CCR) or OSHA’s proposed new heat rule.

This is the shortest research article I ever wrote but it was the most satisfying experience. We talk a lot about interdisciplinary research but this is a real example showing how a marriage between weather modeling and the public health sector can create something totally new—a policy child. Thanks to our PI Trent Biggs for persisting on this idea.

Science progresses slowly so it is important to capitalize on the existing scientific knowledge for the benefit of society. That is exactly what we have done here—utilized available Earth science modeling tools, for developing policy guidelines, to protect lives.

On a side note, air pollution and extreme heat are two real issues we should be concerned about right now. More than 7 million people around the world die every year due to air pollution, which is now the second leading risk factor for death in children (after malnutrition). Another half million die due to extreme heat, the majority of whom are our own parents (called seniors in professional language). I continue to work on these important health issues using my skills in weather prediction and air pollution modeling. I welcome any collaborations on these issues.

Imperial Valley Environmental Justice Summit

By Sagar Parajuli

On October 24, 2024

In Dust, Climate, Environment, and Society

Some 100 miles east of San Diego, lives a big agri-town called Imperial Valley (IV) that supplies 2/3 of the winter vegetables and 1/3 of the fruits/vegetables consumed in the entire US. Majority of IV residents are hispanic with 25% living below poverty line and the majority of farmworkers are migrant workers coming from Mexicali across the US-Mexico border. IV has high rates of asthma (one in five children) and the highest heat-related illness rate in the entire state. Several environmental threats contribute to these issues, including the harsh desert climate, the shrinking Salton Sea, blowing dust storms, pesticides-laden runoff from highly irrigated lands, agricultural activities that produce dust and smoke, rapid urbanization, industrial expansion, and now the lithium exploration activities.

State and Federal government representatives, local NGOs and community members, researchers, and most importantly, the farmworkers, met to discuss about how to deal with the emerging environmental challenges of the region in an event called EJSummit. The Environmental Health Leadership Summit (EJSummit) is an annual event organized by a local community organization called Comite Civico del Valle now in its 13th year. The event occured on October 22/23 this year, right next to the agricultural fields of the IV in El Centro, CA.

Following points were noted:

The hot brine below the Salton Sea (not the Salton Sea water) has enough Lithium to meet 1/3 of today’s global demand. The proposed Direct Lithium Extraction method extracts lithium from brine directly using more environmental friendly technique using a adsorption material thereby rejecting the brine which is reinjected underground, but the technology has not been implemented in industrial scale so the reality of anticipated ‘Lithium Valley’ is yet to be realized.
The Salton Sea continues to shrink due to high rate of evaporation combined with reduced inflow of water caused by the Quantification Settlement Agreement (QSA) of 2003 that diverted some 15% water to San Diego region. The local people mentioned that many people have lost their jobs due to reduced agricultural activities, caused by the reduced water inflow to the IV crop fields.
Speakers included 84-year old living legend Preston Arrow-Weed (in picture), a member of Kumeyaay tribe, who lived in this region for thousands of years. Who else can better teach how to reduce our environmental footprint and to live in harmony with nature?

California is not just about Silicon Valley

By Sagar Parajuli

On January 20, 2024

In Environment and Climate

California is not just about Silicon Valley; it is the Central Valley and the Imperial Valley (IV) that truly define California’s richness, as they produce more than half of the fruits, vegetables, and nuts consumed in the United States. The Imperial Valley, which lies on the south side of the Salton Sea, alone provides more than 80% of the nation’s fresh winter fruits and vegetables. But have you ever wondered how those succulent oranges, almonds, and lettuces come to your table every day?

An overview of the Salton Sea/Imperial Valley region. Picture courtesy of USGS: https://eros.usgs.gov/earthshots/imperial-valley-california-usa

Unfortunately, the farm workers in the Imperial Valley experience a high number of cardiovascular diseases due to heat stress. Not only this, the IV region is recently going through tremendous environmental stress due to water and air pollution; extreme droughts and flooding; and land use change.

I have built a high-resolution, high-performance regional climate model set up around the Imperial Valley (WRF-IV) that can be used to address such environmental concerns. As an example, the model can simulate how the microclimate will change when croplands are converted to solar fields. Similarly, the model can be used to calculate the heat stress experienced by farm workers at a specific time and location.

What question intrigues you the most about this region?