Air Quality & Wind

Why Wind Direction Matters

Fire training activities produce smoke, airborne particulates, and potentially PFAS-contaminated emissions. The direction these travel is determined by prevailing wind patterns — and at the Four Hills site, prevailing WNW/NW winds carry these pollutants south-southeast toward residential neighborhoods along Gosselin Road, Twilight Drive, and the Main Dunstable Road corridor.

The Concern

Downwind Receptors

Based on prevailing WNW/NW winds, the plume travels south-southeast from the facility. The dispersion path cuts across three Nashua wards — Ward 5, Ward 8, and Ward 9 — affecting thousands of residents:

• Gosselin Road / Echo Avenue — directly in the plume path within ¼ mile
• Twilight Drive / Acacia Street — within the ½ mile dispersion zone
• Michael Avenue / Main Dunstable Road corridor — within 1 mile, along NH 111A
• Teak Drive residents — closest to the facility (~adjacent), affected by proximity even if not directly downwind

Not “Occasional Use” — This Will Be a Daily Operation

During ZBA hearings, Chief Buxton described current facility usage as “once or twice a week” for Nashua alone, plus a 30-day recruit school in spring and ~6 visits per year from abutting towns. The ZBA cited this “two to three times a week” frequency as a key reason for denial, calling it “not tenable for the kind of quiet residential neighborhood.”

The city’s own CIP request to the Finance Committee (Feb 2026) confirms this is now an “all-hazards” facility. The document states: “the Fire Service has transitioned from just fighting fires to an all-hazards agency” and the new site will “allow us room to expand our training needs.” (Source)

• $1,980,000 requested for FY27 — building cost alone. Road and water line are separate budgets
• Upwards of 12 departments expected to use the expanded facility (conversations with city officials)
• Expanded scope beyond fire training to include hazardous materials response
• Board member Bashek at ZBA: “If this were just for fire department use perhaps, but the unknown is what it would attract from other communities”

This transforms the facility from occasional use into daily operations with fire trucks and hazmat vehicles from across the region — all routing through residential neighborhoods.

Incompatible with Neighborhood Character

On October 14, 2025, the ZBA denied the road application 5-0 on criteria 2 (traffic) and criteria 5 (neighborhood character). The chairman stated: “this is really buried in a residential neighborhood. I can’t get past the degree to which the character of this neighborhood would change irreparably.” (ZBA Hearing — Oct 14, 2025, 2:16:49)

Since that denial, the facility has grown from occasional fire training to daily “all-hazards” operations — the city’s own term (Finance Committee CIP, Feb 2026). “All-hazards” means hazardous materials response and chemical training, not just fire. Daily smoke, particulates, and airborne PFAS carried by prevailing WNW/NW winds into residential neighborhoods along Gosselin Road, Twilight Drive, and Main Dunstable Road is not consistent with the character of a quiet residential area — it is the kind of irreparable change the board described.

Board member Bashek warned at the October 14 hearing: “the unknown is what it would attract from other communities” (ZBA Hearing — Oct 14, 2025). City officials now indicate upwards of 12 departments are expected to use the expanded facility, routing hazmat vehicles from across the region through residential streets. Even the lower frequency presented at the ZBA — “two to three times a week” — was enough for the board to call it “not tenable for the kind of quiet residential neighborhood.” The expanded all-hazards scope makes it exponentially worse.

What Gets Carried by Wind

During fire training exercises:

• Smoke and particulates from controlled burns
• PFAS compounds released during combustion of contaminated materials
• AFFF residue if aqueous film-forming foam is used
• Combustion byproducts including volatile organic compounds

No Federal Air Standards for PFAS

A critical regulatory gap:

• There are no federal air emission standards for PFAS as of 2026
• Few states have any PFAS air restrictions — New Hampshire has among the strictest standards
• The PFAS investigation scope at Four Hills explicitly excludes air permitting

Scientific Evidence: This Is Not Speculation

The risk of airborne PFAS contamination from fire training facilities is documented by peer-reviewed research, the EPA, and multiple state environmental agencies.

How Far Does Airborne PFAS Travel?

The Interstate Technology & Regulatory Council (ITRC) — the authoritative multi-state regulatory body on PFAS — states that PFAS contamination from atmospheric transport and deposition can occur “several miles” from emission sources. When AFFF is burned, PFAS compounds bind to fine particulate matter (PM2.5) and are carried downwind.

An EPA atmospheric model (D’Ambro et al., 2021) found that PFAS deposition extends at least 35 km (22 miles) from an emission source, with only 5% deposited within that range — the rest travels even further.

Documented Cases Across the Country

Location	Distance	What Happened
Bennington, VT	10+ miles	Airborne PFOA from a manufacturing facility created a deposition plume covering 120 square miles. PFOA was found in mountain springs 5 miles downwind and 300 meters vertically above the source — proving airborne transport, not groundwater. 2,365 properties contaminated. (Lossner et al., 2021)
Fayetteville, NC	25 miles	Airborne PFAS emissions from one facility contaminated 11,000+ private wells across 10 counties. (NC Health News)
NH Fire Academy	On-site	NHDES confirmed “fairly high levels” of PFAS in groundwater from 175 training courses using AFFF since 1994. (WMUR)
Pease AFB, Portsmouth NH	Off-base	PFAS from fire training AFFF migrated beyond base boundaries into residential wells in Newington, Greenland, and Portsmouth. (NHDES)
300+ US military bases	Variable	Confirmed PFAS in drinking water or groundwater on or near bases, primarily from fire training areas. (EWG)

Smoke and Particulate Matter

Even without the PFAS issue, smoke from open burns is a documented health hazard:

• Immediately downwind of prescribed burns, PM2.5 concentrations can reach 72 times the EPA 24-hour standard (Naeher et al., 2006)
• Studies detect elevated PM2.5 at 1, 2, and 4 miles downwind of burn sites (Achtemeier et al., 2012)
• Prescribed fire smoke has been linked to increased asthma-related ER visits in downwind communities (Gan et al., 2017)

PFAS Doesn’t Break Down

Terminal PFAS compounds like PFOS and PFOA do not appreciably degrade in the environment. A 2023 study of military fire training sites found PFAS contamination will persist above regulatory guidelines for centuries without active remediation. These are called “forever chemicals” for a reason.

The Regulatory Gap

• There are no federal air emission standards for PFAS as of 2026
• New Hampshire banned PFAS-containing foam for training effective January 1, 2020 (RSA 154:8-d), but legacy contamination from prior use remains
• The PFAS investigation scope at Four Hills explicitly excludes air permitting
• NH collected over 10,000 gallons of AFFF from 100+ fire departments through its Take Back Program — evidence of how widespread the problem is

What Needs to Happen

1. Air dispersion modeling showing potential contaminant transport to residential areas — not just groundwater testing
2. Air monitoring plan with real-time PM2.5 and PFAS sampling during any burn activities
3. Health risk assessment for all downwind residential populations across Wards 5, 8, and 9 — the 15x PFAS dispersion model reaches 4 miles (see note below)
4. Include air permitting in the PFAS investigation scope (currently excluded)
5. Independent review of wind data using local weather station normals, not consultant estimates

About the “15x PFAS” Dispersion Model

The interactive map on this page includes a “15x PFAS — After Expansion” toggle. This models the increased PFAS dispersion risk if the facility expands from its current use — described at ZBA hearings as “once or twice a week” for Nashua alone — to the daily, all-hazards, multi-department operation described in the city’s own CIP request. With 12+ departments using the site for fire training, hazmat response, and recruit schools, burn frequency and PFAS-laden emissions could increase by an estimated 10–15 times. The wider plume (55° vs 40°) and extended range (4 miles) reflect peer-reviewed findings that airborne PFAS deposits across wide areas — EPA modeling shows PFAS deposition at 35+ km from source (D’Ambro et al., 2021), and in Bennington, VT, airborne PFOA covered 120 sq mi from a single industrial source (Lossner et al., 2021).

Source Documents

ZBA Hearings & City Documents

• ZBA Hearing — Oct 14, 2025 [12:41] — Fire Chief: “We burn only clean wood and hay”
• ZBA Hearing — Oct 14, 2025 [2:16:49] — Chairman: neighborhood character would “change irreparably” (criteria 2 + 5 denial)
• ZBA Hearing — Nov 25, 2025 [1:31:03] — Commissioner Kelly repeats “clean wood and hay” claim
• Finance Committee CIP — Feb 2026 — “all-hazards agency,” $1.98M, 12+ departments
• NHDES PFAS Investigation — $236,800 contract with Sanborn Head & Associates
• NHDES Director confirms PFAS to NH Senate — Feb 4, 2026

Peer-Reviewed Research & Scientific Sources

• D’Ambro et al., 2021 — EPA atmospheric PFAS model — PFAS deposition extends at least 35 km (22 miles), only 5% within range
• ITRC PFAS Environmental Fate & Transport — atmospheric PFAS transport “several miles” from source
• Barton et al., 2023 — PFAS persistence at military fire training sites — contamination persists for centuries
• Naeher et al., 2006 — Smoke exposure from prescribed burns — PM2.5 reaches 72x EPA standard immediately downwind
• Achtemeier et al., 2012 — Downwind PM2.5 transport — elevated PM2.5 detected at 1, 2, and 4 miles
• Gan et al., 2017 — Smoke and asthma ER visits — increased asthma-related ER visits in downwind communities

Documented Cases

• Lossner et al., 2021 — Bennington, VT — airborne PFOA deposition plume covering 120 sq mi, 2,365 properties contaminated
• NC Health News — Fayetteville, NC — airborne PFAS contaminated 11,000+ wells across 25 miles
• WMUR — NH Fire Academy — “fairly high levels” of PFAS from 175 training courses
• NHDES — Pease AFB, Portsmouth NH — PFAS migrated beyond base boundaries into residential wells
• EWG — 300+ US military bases — confirmed PFAS from fire training areas

Regulatory

• NH RSA 154:8-d — PFAS foam training ban effective Jan 1, 2020